GOST R ISO 148-1-2013

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  ГОСТ Р ИСО 148-1-2013

GOST R ISO 148−1-2013 Materials metal. Impact test bend on the pendulum Koper in Sharpie. Part 1. Test method

GOST R ISO 148−1-2013

NATIONAL STANDARD OF THE RUSSIAN FEDERATION

The metal materials. Impact test bend on the pendulum Koper in Sharpie. Part 1. Test method

Metallic materials. Charpy pendulum impact test. Part 1. Test method

OKS 77.080*
______________
* ICS 11−2014 GOST R ISO 148−1-2013 is
ACS 77.040.10. — Note the manufacturer’s database.

Date of introduction 2014−10−01

Preface

1 PREPARED AND SUBMITTED by the Technical Committee for standardization TC 145 «monitoring Methods of steel products».

2 APPROVED AND put INTO EFFECT by the Federal Agency for technical regulation and Metrology, dated 22 November 2013 No. 2053-St

3 this standard is identical with ISO 148−1:2009* metal Materials — Testing the impact strength Charpy with pendulum Part 1: test Method (ISO 148−1:2009 «Metallic materials — Charpy pendulum impact test — Part 1: Test method"
In applying this standard it is recommended to use instead of the referenced international standards corresponding national standards of the Russian Federation and interstate standards, details of which are given in Appendix YES

4 INTRODUCED FOR THE FIRST TIME

Application rules of this standard are established in GOST R 1.0−2012 (section 8). Information about the changes to this standard is published in the annual (as of January 1 of the current year) reference index „National standards“ and the official text changes and amendments — in monthly information index „National standards“. In case of revision (replacement) or cancellation of this standard a notification will be published in a future issue of information index „National standards“. Relevant information, notification and lyrics are also posted in the information system of General use — on the official website of the Federal Agency for technical regulation and Metrology on the Internet (gost.ru)

1 Scope

This standard applies to metallic materials and sets the method of testing the impact strength of samples with V-shaped or c U-shaped notch Charpy using the pendulum to determine the absorbed impact energy.

2 Normative references

This standard uses the regulatory references to the following international standards*:
________________
* The table of conformity of national standards international see the link. — Note the manufacturer’s database.


ISO 148−2:2008 metallic Materials. The test impact strength Charpy with the help of a pendulum. Part 2. Testing (verification) testing machines (ISO 148−2:2008, Metallic materials — Charpy pendulum impact test — Part 2: Verification of testing machines)

ISO 148−3:2008 Metallic materials. Impact test pendulum Koper in Sharpie. Part 2. Verification of testing machines

(ISO 148−3:2008, Metallic materials — Charpy pendulum impact test — Part 3: Preparation and) characterization of Charpy V-notch test pieces for indirect verification of pendulum impact machines)

ISO 286−1:2008. The geometric characteristics of the products. ISO code system for tolerances of linear sizes. Part 1. Base tolerances, deviations and fits (ISO 286−1:2008, Geometrical product specifications (GPS) — ISO code system for tolerances on linear sizes — Part 1: Basis of tolerances, deviations and fits)

ISO 3785:2006 metallic Materials. Marking the axes of the test specimens relative to the texture of the product (ISO 3785−2006, Metallic materials — Designation of test specimen axes in relation to product texture)

ISO 14556−2006 Steel. The test impact strength Charpy specimens with a V-shaped incision. Instrumental test method (ISO 14556−2006, Steel — Charpy V-notch pendulum impact test — Instrumented test method)

ASTM E 23−96 Metallic materials. Standard methods of testing the impact strength when using notched specimens (ASTM E 23−96, Standard Test Methods for Notched Bar Impact Testing of Metallic Materials)

3 Terms and definitions

This standard applies the following terms with respective definitions:

3.1 Energy:

3.1.1 initial potential energy of Cu (initial potential energy): the Difference between the potential energy of the pendulum before release for testing and potential energy in the position of the impact determined by direct verification (validation) (ISO 148−2).

3.1.2 absorbed energy (absorbed energy): the Energy required to break the specimen in pendulum Koper, adjusted for losses in friction.

Note — To designate the geometry of the notch using the letters V or U, i.e.: or. To denote the radius of the striker in the form of index point figure 2 or 8, for example .

3.2 Sample

For sample, placed on the machine feet in test position, apply the following dimension names (figure 1):

3.2.1 height (height), mm: the Distance between the face of the specimen with incision and an opposite side;

3.2.2 width (width), mm: the distance, measured perpendicularly to the height parallel to the incision;

3.2.3 length (length) mm: the largest dimension at right angles to the incision.

Figure 1 — the Scheme supports and anvils (stops) impact testing machines, pendulum

 — height of the test specimen; is the length of the test sample; is the width of the test sample; center punch;  — the direction of oscillation of the pendulum; 1 — anvil (stops); 2 — sample standard size; 3 — a support for the test sample; 4 — a protective casing

Figure 1 — the Scheme supports and anvils (stops) impact testing machines, pendulum

4 Designations and names of parameters

Symbols and names of parameters used in this standard are given in tables 1 and 2 and shown in figure 2


Table 1 — symbols, units and description

Marking	Unit	The name of the parameter
Cu	J.	Initial potential energy (potential energy)
	%	The relative square of viscous shear fracture appearance
	mm	The height of the sample
	J.	Absorbed energy for sample with U-shaped incision upon impact, two-millimeter head
	J.	Absorbed energy for sample with U-shaped incision upon impact of the striker eight millimeter
	J.	Absorbed energy for sample with V-shaped cut in the two-millimeter punch striker
	J.	Absorbed energy for sample with V-shaped cut when you hit the eight-millimeter head
	mm	Lateral expansion
	mm	The length of the sample
	°C	Junction temperature
	mm	Width of test sample

Table 2 — Permitted maximum deviations from the established dimensions of the samples

The sample size	Refer to increase	Sample V-neck cut			Sample with a U-shaped cut
Nominal size	Tolerance for machining		Nominal size	Tolerance for machining
The value	Class of admission	The value	Class of admission
Length		55 mm	±0.60 mm	js15	55 mm	±0.60 mm	js15
Height		10 mm	±0,075	js12	10 mm	±0,11 mm	js13
Width:
standard test sample;	10 mm	±0,11	js13	10 mm	±0,11 mm	js13
the specimen with reduced cross section	7.5 mm	±0,11	js13	-	-	-
the specimen with reduced cross section	5 mm	±0,06	js12	-	-	-
the specimen with reduced cross section	2.5 mm	±0,05	js12	-	-	-
The angle of the incision	1	45°	±2°	-	-	-	-
Heights of cut (height of the specimen minus the notch depth)	2	8 mm	±0,075	js12	5 mm	±0,09	js13
The radius of curvature at the base of the incision	3	0.25 mm	±0.025 mm	1 mm	±0.07 mm	js12
The distance from the plane of symmetry of the incision to the ends of the sample	4	27.5 mm	±0,42 mm	js15	27.5 mm	±0,42 mm	js15
The angle between the plane of symmetry of notch and longitudinal axis of specimen	-	90°	±2°	-	90°	±2°	-
The angle between the adjacent longitudinal surfaces of the sample	5	90°	±2°	-	90°	±2°
In accordance with ISO 286−1. The samples should have a surface roughness better than 5 µm, with the exception of the ends. If you specify other height (2 or 3 mm), corresponding tolerances must also be specified. For machines with automatic positioning of the test sample, it is recommended that the tolerance was taken as ±0,165 mm, is ±0,42 mm.

Figure 2 — Samples for testing the impact strength according to the method of Sharlee with pendulum

A — Geometry of the specimen with a V-shaped incision; — the Geometry of the specimen with the U-shaped incision

Note — Designations , , and the numbers 1−5 refer to table 2.

Figure 2 — Samples for testing the impact strength according to the method of Sharlee with pendulum

5 the essence of the method

The essence of the method consists in the destruction of the sample with the incision in one stroke pendulum under the conditions described in sections 6−8. An incision in the sample has the desired geometry and is in the middle between the two pillars opposite the position at which to strike. Determine the energy absorbed by the specimen during the test.

Because the values of impact energy for different metallic materials are temperature dependent, the test is carried out at given temperatures. If the temperature differs from ambient, sample heated or cooled to this temperature in a controlled environment.

6 Samples

6.1 General

The length of the standard sample shall be 55 mm, and the cross-section have the shape of a square with sides of 10 mm length in the Middle of doing a V-shaped or U-shaped incision, by 6.2.1 or 6.2.2, respectively.

If the standard sample cannot be obtained from existing material, use one of the smaller sample size with a width of 7.5, 5 or 2.5 mm (figure 2 and table 2).

Note — At low energy values it is necessary to use shims, then the excess energy will be absorbed by the pendulum. At high energy it may not matter that much. Strips can be placed on poles or under them so that the mid-height of the sample was 5 mm above the surface of the support, i.e. at a distance of 10 mm from the surface of the sample support.


The surface roughness of the samples should be above 5 µm, except for the ends.

When testing heat-treated material, the specimen shall be subjected to fine machining, including cut.

6.2 Geometry of cuts

The incision needs to be prepared thoroughly: on the surface along the radius of the bottom of the incision should not be traces of machining, which could affect the value of the absorbed energy.

The plane of symmetry of the notch should be perpendicular to the longitudinal axis of the test sample (see figure 2).

6.2.1 V-shaped incision

V-shaped incision needs to have an internal angle of 45°, a depth of 2 mm and the radius of the base of the notch of 0.25 mm (figure 2A and table 2).

6.2.2 U-shaped incision

U-shaped incision should have a depth of 5 mm (unless otherwise specified) and a base radius of 1 mm incision (figure 2b and table 2).

6.3 maximum deviations of the sizes of the samples

Tolerances on specified dimensions of samples and cuts is shown in figure 2 and table 2.

6.4 sample Preparation

The preparation of samples should be conducted in such a way as to minimize any change of pattern, for example due to heating or cooling.

6.5 Marking of samples

The marking is applied on any face of the sample is not in contact with the supports, the anvil (with stops) or the striker, in a place not subject to plastic deformation and formation of surface discontinuities in the result, the absorbed energy measured during the test (see 8.7).

7 testing Equipment

7.1 General provisions

Test equipment must be specified in the regulations. The calibration (or verification) of the equipment should be carried out with sufficient frequency and within the required ranges.

7.2 Installation and testing (verification)

Installation and verification (verification) testing machines is carried out in accordance with ISO 148−2.

7.3. PEEN

The geometry of the firing pin is set as a two-millimeter or eight millimeter firing pin. It is recommended that the radius of the firing pin was specified as a subscript as follows: or .

The geometry used firing pin needs to be specified in the technical requirements (specifications) of the subject products.

Note — Some materials may give significantly different results at low energy levels, and the results obtained for the 2-mm striker will be higher than for an 8 mm.

8 testing

8.1 General provisions

The test sample should lie on the supports of the testing machine so that the plane of symmetry of the notch was located within 0.5 mm from the mid plane between stops. The blow of the firing pin should be applied in the plane of symmetry of the notch on the side opposite the incision (see figure 1).

8.2. Test temperature

8.2.1 Unless otherwise specified, the tests carried out at a temperature of (23±5)°C. If the temperature is specified, the sample should be brought to this temperature with an accuracy of ±2°C.

8.2.2 conditioning (bringing the sample to a predetermined temperature) by heating or cooling with a liquid medium sample is placed in a container on the grid, located at a distance of not less than 25 mm above the bottom of the container and 25 mm below the liquid level and not closer than 10 mm from the side surfaces of the container. The environment is constantly stirred and brought to the desired temperature in any convenient way. A device for measuring the temperature of the medium should be placed in the middle of a group of test specimens. The temperature of the medium must be maintained at a predetermined level with an accuracy of ±1°C for at least 5 min.

Note — If the liquid temperature close to the temperature of its boiling point, cooling by evaporation can significantly lower the temperature of the test sample over a period of time from its extraction from the liquid before the destruction.

8.2.3 For conditioning of the sample by heating or cooling through a gaseous sample placed in a chamber at a distance of not less than 50 mm from the nearest surface. The distance between the individual samples must be at least 10 mm.

The environment is constantly pumped to ensure its circulation, and brought to the desired temperature in any convenient way. Use a device to measure the temperature of the environment should be placed in the middle of a group of samples. The temperature of the gaseous environment must be maintained at a predetermined level with an accuracy of ±1°C for at least 30 minutes.

8.3 sample Transfer

If the test is carried out at a temperature different from ambient temperature after extraction of the sample from the heating or cooling medium to strike at him, the striker shall not exceed 5 s.

Device for sample transfer should be specially designed for this purpose and used in such a way that the sample temperature was maintained within the acceptable range.

Of the device in contact with the sample when it is transferred from the environment to the machine must have the same set temperature and be conditioned with the sample.

You must make sure that the device is used for centering the sample on the anvil (stops), did not cause rebound destroyed all high-strength specimens in a pendulum, which can lead to erroneously high readings of energy. To do this, the gap between the ends of the specimen in the test position and the centering device or the fixed machine parts shall be not less than 13 mm, otherwise the destruction process can occur a rebound of the ends of the specimen in the pendulum.

Note — For the transfer of samples from the environment for conditioning at the test often used self-centering pliers similar to those shown for samples with a V-shaped incision in Annex A. This kind of pliers eliminate the problems with clearance due to the engagement between the two halves of the destroyed sample and the stationary centering device.

8.4 exceeding the capacity of the testing machine

It is recommended that the absorbed energy does not exceed 80% of the initial potential energy . If the absorbed energy exceeds 80% of the capacity of the machine, the resulting value must be specified in the test report.

Note — Testing the impact strength should be at a constant speed of impact. In real conditions, when tested using the pendulum speed decreases with the development of fracture. For samples with impact energy, approaching the power of pendulum, the speed of the pendulum decreases during the destruction of the specimen to the moment when the exact values of impact energy to anymore.

8.5 Partial destruction

If the test sample is not destroyed completely, then the energy of impact stipulate in the Protocol together with the results completely destroyed the samples or average them.

8.6 jamming of the sample

If the sample is jammed in the machine, the results do not take into account and carefully check the machine for damage that could affect its calibration.

Note — Jamming occurs when the sample gets destroyed between the movable and fixed parts of the testing machine. This can lead to the absorption of a considerable part of energy. Jamming is different from the secondary markings from the firing pin is the fact that by jamming on the sample of observed couple of marks opposite each other.

8.7 Control following the destruction

If the inspection of the sample after the destruction will be that the part marking is located on the site visible on the specimen, and the test result as invalid, and this should be reflected in the test report.

9 test report

9.1 Compulsory information

The test report shall contain:

a) reference to this standard;

b) identification of the test sample (e.g., type of steel and the melting number);

c) type of incision;

d) the sample size if the sample is not full size;

e) the desired temperature of the sample during testing;

f) absorbed energy , , or , depending on the specific case;

g) any deviation that may affect the test results.

9.2 Additional information

In the test Protocol may be included (in addition to 9.1), the following information:

a) orientation of the sample (ISO 3785);

b) the nominal energy of the testing machine in joules;

c) a transverse (lateral) extension (Annex b);

d) appearance of the fracture, the relative shift (Annex C);

e) the curve of dependence of the absorbed energy temperature (D. 1, Annex D);

f) characterization of the dependence of the absorbed energy temperature (D. 1, Annex D);

g) number of test specimens, completely destroyed during the test;

h) measurement uncertainty (Appendix E).

Annex a (informative). Self-centering pliers

Appendix A
(reference)

The tongs shown in figure A. 1, is often used to transfer the sample from the medium for conditioning the sample at a certain temperature to the required position on the machine for testing the impact strength Charpy.

Figure A. 1 — Centering jaws for samples with a V-shaped cut

Sample width	The width of the base, And	The height of the base,
10	From 1.60 to 1.70	From 1.52 to 1.65
5	It ranged from 0.74 to 0.80	Between 0.69 to 0.81
3	From 0.45 to 0.51	From 0,36 to 0,48

_______________
Steel strips soldered to the forceps silver solder parallel to each other.

Figure A. 1 — Centering jaws for samples with a V-shaped cut

Annex b (informative). Transverse (lateral) extension

The App
(reference)

B. 1 General provisions

A measure of the ability of a material to resist destruction under the action of triaxial stresses, such as those that occur at the bottom of the notch of the Charpy sample is the strain value at a given location. We are talking about deformation. Because of the difficulty of measuring this deformation, even after the destruction is usually measured expansion, which may occur at the opposite end of the plane of the fracture and are used as a value representing a compressive strain.
_______________
The app is based on ASTM E 23 and is used in coordination with ASTM International.

B. 2 Procedure

When using the method of measuring lateral expansion must take into account the fact that the plane of fracture is rarely divides the sample in half at the point of maximum expansion on both sides of the sample. Half-destroyed design may include the area of the maximum extension for both sides, only one side or not to include the extension at all. Thus, the methods used should give the value of the extension is equal to the sum of the two values obtained for each side by separate measurements of two halves. The extension on each face of each half is measured relative to the plane defined by the undeformed portion of the edge of the sample (figure V. 1). The extension is measured using a device similar to that shown in figures V. 2 and V. 3. Measure two shattered halves separately. First, however, check the edge, perpendicular to the incision, no burrs, which could be formed when testing the impact strength; in the presence of such burrs should be removed with emery cloth, while keeping an eye to the measured projections were not removed together with the burrs. Then fold the halves of the specimen together so that the surfaces which in the initial state was the opposite of the incision were facing each other. One of the halves of the sample (see figure B. 1 1) tightly to the supports that the projections rested on the measuring anvil. Note the reading, then repeat with the other half (figure B. 1, 2), making sure to measure the same line. The largest of the two values corresponds to the extension side of the sample. Then repeat this procedure to measure the protrusions on the opposite face, then put the highest value obtained for each side face. For example, if and , then . If and , then .

If one or more projections of the specimen was damaged upon contact with the anvil support surface copra machines, etc., measurements for this sample do not perform and this fact is reflected in the test report.

The measurements were carried out on each sample

Figure B. 1 — Half destroyed in the process of testing the impact strength Charpy specimen with a V-shaped incision, and United for the measurement of lateral expansion

1, 2 — Halves of the sample;  — the initial width of the sample;
, , ,  — the dimensions of the side extensions

Figure B. 1 — Half destroyed in the process of testing the impact strength Charpy specimen with a V-shaped incision, and United for the measurement of lateral expansion

Figure B. 2 — a Device for measuring lateral (pepper) extensions samples

Figure B. 2 — a Device for measuring lateral (pepper) extensions samples

Figure B. 3 — units and parts of installation of the device for measuring the lateral (transverse) expansion

_______________
Screw 20 with a head with a recess with a length of 7/8» for installation of the indicator.

Screw М6х1 with 25mm head.

The overlap in the node (at the Assembly to perform overlapping).

1 — a rubber lining; 2 — the indicator range 10 mm, graded by 1/100 mm; 3 — base plate in stainless or chrome-Nickel steel; 4 — dial holder in stainless or chrome-Nickel steel;

Figure B. 3 — units and parts of installation of the device for measuring the lateral (transverse) expansion

Application (reference). Appearance of fracture

Application
(reference)

C. 1 General provisions

The fracture surface of Charpy samples is often estimated by the percentage of viscous shear fracture. The higher the percentage shear fracture, the higher the toughness of material. On the fracture surface of Charpy most visible combination of shear (ductile) fracture and destruction in the form of cracking (brittle fracture). Because this assessment is subjective, it is not recommended for use in specifications (technical requirements).

Note — the Term «fiber fracture» is often used as a synonym for «viscous break». To Express the opposite States from viscous to fracture, often used the terms «destruction in the form of chips» (brittle fracture) or «crystallinity in the broken places.» Thus, if the proportion of viscous (shear) component of the fracture is 0%, the fragile — 100%.

C. 2 Procedure

The percent ductile fracture is usually defined in one of the following methods described in ASTM E 23:

a) measure the length and width of the area of cracking or brittle fracture («brilliant» plot) fracture surface, as shown in figure C. 1. determine the percentage of ductile shear in table C. 1;

b) compare the appearance of the fracture of the specimen with comparison chart of the types of fracture, such as shown in figure C. 2;

c) increase the fracture surface and compare it with pre-calibrated transparent overlay chart or measure the percent of brittle fracture by using a planimeter, then calculate the percentage of ductile fracture as the difference (100% minus the percent brittle fracture);

d) pictures of the fracture surface with the appropriate magnification and measure the percent brittle fracture by using a planimeter, then calculate the percentage of ductile fracture as the difference (100% minus the percent brittle fracture);

e) measure the percentage of ductile fracture using the methods of image analysis.

Figure C. 1 — determination of the percentage of ductile fracture

Note 1 — the Average sizes A and b are measured with an accuracy of 0.5 mm.

Note 2 — the Percentage of ductile fracture is determined by the table C. 1

1 — cut; 2 — the region of brittle fracture (bright); 3 — ductile shear area (dull)

Figure C. 1 — determination of the percentage of ductile fracture

Table C. 1 — Percentage of ductile shear for measurements made in millimeters

Mm	And, uh
1,0	1,5	2,0	2,5	3,0	3,5	4,0	4,5	5,0	5,5	6,0	6,5	7,0	7,5	8,0	8,5	9,0	9,5	1,0
The percentage of ductile shear
1,0	99	98	98	97	96	96	95	94	94	93	92	92	91	91	90	89	89	88	88
1,5	98	97	96	95	94	93	92	92	91	90	89	88	87	86	85	84	83	82	81
2,0	98	96	95	94	92	91	90	89	88	86	85	84	82	81	80	79	77	76	75
2,5	97	95	94	92	91	89	88	86	84	83	81	80	78	77	75	73	72	70	69
3,0	96	94	92	91	89	87	85	83	81	79	77	76	74	72	70	68	66	Sixty four	62
3,5	96	93	91	89	87	85	82	80	78	76	74	72	69	67	65	63	61	58	56
4,0	95	92	90	88	85	82	80	77	75	72	70	67	65	62	60	57	55	52	50
4,5	94	92	89	86	83	80	77	75	72	69	66	63	61	58	55	52	49	46	44
5,0	94	91	88	85	81	78	75	72	69	66	62	59	56	53	50	47	44	41	37
5,5	93	90	86	83	79	76	72	69	66	62	59	55	52	48	45	42	38	35	31
6,0	92	89	85	81	77	74	70	66	62	Fifty nine	55	51	47	44	40	36	33	29	25
6,5	92	88	84	80	76	72	67	63	59	55	51	47	43	39	35	31	27	23	19
7,0	91	87	82	78	74	69	65	61	56	52	47	43	39	34	30	26	21	17	12
7,5	91	86	81	77	72	67	62	58	53	48	44	39	34	30	25	20	16	11	6
8,0	90	85	80	75	70	65	60	55	50	45	40	35	30	25	20	15	10	5	0
Note: a 100 percent shift should indicate when one of the dimensions A or b is zero.

Figure C. 2 — appearance of the fracture

a — the appearance of fractures and the comparative chart to determine the percentage of ductile shear

In the Guide to assess the appearance of the fracture

Figure C. 2 — appearance of the fracture

Annex D (informative). The dependence of the absorbed energy to the temperature and transition temperature

Appendix D
(reference)

D. 1 Characteristic dependence of the absorbed energy temperature

The curve of dependence of the absorbed energy to the temperature () for a given shape of the sample is shown in figure D. 1. This dependence is set by constructing a smooth curve constructed from individual points. The shape of the curve and the scatter of values obtained in the test depend on the material, the shape of the sample and the impact velocity. In the case where the curve has a transition zone 2, it is necessary to distinguish the top sloping plot of 1, transition zone 2 and the lower flat area 3 of the curve .

Figure D. 1 — the Curve of absorbed energy temperature

 — temperature;  — absorbed energy; 1 — the upper plateau; 2 — transition zone; 3 — lower plateau

Figure D. 1 — the Curve of absorbed energy temperature

D. 2 transition Temperature

Transition temperature characterizes the position of the steep rise characteristics based on the absorbed energy the temperature. Because of the steep climb usually covers a very wide temperature range, it is impossible to give a common definition of transition temperature. The following are the criteria, which among others can be useful for determining the transition temperature:

Transition temperature  — the temperature at which:

a) receive a specific value of the absorbed energy, for example, 27 j;

b) receive a specific value of the absorbed energy as a percentage of the value corresponding to the upper pad, such as 50%;

c) there is some part of the ductile fracture, such as 50%;

d) get a certain value of the transverse (lateral) extensions, e.g. 0.9 mm.

The choice of method for determining the transition temperature should be included in the standard for steel or according.

Annex E (informative). Uncertainty of measurement values of the absorbed energy KV

Annex E
(reference)

E. 1 Notation and units of measurement

Notations and units are given in table E. 1


Table E. 1 — Symbols and units of measurement

Marking	Unit	Feature
	J.	Systematic error of pendulum, some indirect validation (verification)
	-	Enrolment
	J.	The absorbed energy, measured in accordance with this standard for the sample with V-shaped cut
	J.	The average value for the group of samples made from the test material
	J.	The certified value of the reference material used for the indirect verification (verification)
	J.	The average value for the reference samples tested during indirect testing (verification)
	The number of samples tested
	The resolution of the instrument scale
	J.	Standard deviation of the values obtained on samples
	J.	The temperature error of the measured values
	J.	Standard uncertainty
	J.	The expanded uncertainty with a confidence level of 95%
	To	The standard uncertainty of test temperature
	J.	The standard uncertainty of the result of indirect testing (verification)
	J.	Standard uncertainty
	J.	The average value found by results of testing groups of samples made from the test material
	-	The number of degrees of freedom corresponding to
	-	The number of degrees of freedom corresponding to
	-	The number of degrees of freedom corresponding to

E. 2 Definition of uncertainty of measurement

E. 2.1 General provisions

This Annex specifies a method for determining the uncertainty associated with the average absorbed energy of a group of samples taken from the test material. You can also use other methods of assessment .

This approach requires the source of information obtained in «indirect verification (verification)» testing machine for Charpy impact strength with pendulum, which is a standard method of evaluation of the characteristics of the instrument using reference samples (ISO 148−2).

Note 1 — In the ISO 148−1, ISO 148−3 determined that the machines for testing samples by the Charpy method for impact strength using the pendulum must meet the requirements of both indirect and direct examination. The latter consists in checking the compliance of all individual geometrical and mechanical requirements for the device design (ISO 148−2).


Calibration laboratories use certified reference standards for the validation (verification) of their reference testing machines and can apply their pendulum copra to obtain the characteristics of the reference samples. On the user level, lab, testing, Charpy, unable to check its pendulum copra according to the reference samples to obtain reliable values of KV.

Note 2 Users, at its option, can purchase certified reference standards from national or international organizations, thereby bypassing the level calibration laboratories.

Note 3 — Additional information about the differences between certified standards and reference samples are given in ISO 148−3.

E. 2.2 Additions to the definition of uncertainty

Analysis of measurement uncertainty is a useful means of identifying large discrepancies of measurement results.

Product standards and a database of properties of materials based on this standard, contain measurement uncertainty. It would be incorrect to introduce corrections for measurement uncertainty and thereby risk the refusal to accept a suitable production. Therefore, the assessment of uncertainty in this procedure are for reference only, if the customer is not otherwise specified.

The test conditions and the limits of measurement specified in this standard cannot be modified to take account of measurement uncertainty, if the customer does not specify otherwise. You should not combine the evaluation of measurement uncertainty with actual measured results for evaluation of product compliance standards, if the customer does not specify otherwise.

E. 3 the General procedure

E. 3.1 Sources of contributions to the uncertainty

The main factors that influence the uncertainty associated with:

a) systematic error of the instrument determined as a result of indirect verification;

b) homogeneity of the test material and the precision of the measurement instrument;

c) the test temperature.

The average absorbed energy is determined by the formula:

, (E. 1)

where is the observed mean value based on results of testing groups of samples taken from the test material;

 — the systematic error of the instrument, some indirect validation (verification);

 — the temperature error of the measured values .

E. 3.2 the Systematic error of the instrument

As a rule, the measurement result it is necessary to correct for known systematic error. One of the ways to determine the value of a systematic error is an indirect test. The systematic error of the instrument according to the results of indirect testing (verification) defined in ISO 148−2 by the following formula:

, (E. 2)

where  — the average value obtained for reference specimens that were destroyed during the indirect inspections;

 — the certified value of the reference samples.

Depending on how well-known systematic error of the instrument , (ISO 148:2), defines the uncertainty associated with the results of indirect testing, offer different actions:

a) well known and stable — in this exceptional case, to obtain the value , observed value , a correction equal ;

b) in the absence of reliable evidence about the stability of values ; a correction for systematic error is not introduced; in this case, it is presented in the form of a contribution to the uncertainty of the result of indirect testing .

In both cases the enumeration of a) and b), the uncertainty associated with the result of indirect verification and systematic error of the instrument calculated in accordance with ISO 148−2. The result of the analysis of the uncertainty of indirect testing is the value .

If the difference between values and significant values and should be multiplied by the ratio .

E. 3.3 repeatability of measurements of the testing machine and the heterogeneity of the material

The uncertainty values , i.e. the observed average value of the absorbed energy on the test results of the samples, determined by the following formula:

, (E. 3)

where  — standard deviation of values obtained from test samples.

The value is due to two factors: the convergence of the results of measurement of the testing machine and the heterogeneity of the material from sample to sample. In the report it is recommended to specify the total uncertainty of measurement together with the value as a cumulative assessment due to the heterogeneity of the material.

A value representing the number of degrees of freedom is calculated as .

E. 3.4 Temperature error

The effect of temperature error on the absorbed energy greatly depends on the test material. If you are testing the steel in the temperature region of transition from the brittle state to a viscous, slight temperature changes can correspond to large differences in the absorbed energy. It is difficult to give a generalized approach to the calculation based on the measurement uncertainty of the test temperature from uncertainty in the estimation of the absorbed energy. In this regard, it is allowed to complement the reporting information about the measurement uncertainty of the absorbed energy of the individual indication values , i.e. uncertainty in the estimation of the test temperature, which was measured absorbed energy (see example E. 5).

E. 3.5 resolution of the testing machine

The impact of the resolution of the testing machine in many cases is negligible compared to the influence of other factors on the measurement uncertainty (E. 3.1 and E. 3.4) the Exception is the case when the resolution of the machine is low and the energy measured is small. In this case, a corresponding influence on the uncertainty is calculated by the formula:

. (E. 4)

E. 4 Combined and expanded uncertainty

To calculate the need to combine factors that affect the measurement uncertainty (see E. 3). Since is treated separately and members , and are independent from each other, the combined standard uncertainty is determined by the formula:

, (E. 5)

For calculation of expanded uncertainty the combined standard uncertainty is multiplied by the appropriate factor coverage . The value depends on the effective number of degrees of freedom and which can be calculated according to the formula (E. 6). As the number of degrees of freedom, corresponding , equal to infinity, then the resolution of the device is not affected in the .

(E. 6)

Note — When testing Charpy samples is often limited to 5 or even 3. In addition, the heterogeneity of the samples often leads to a significant value . Therefore, the effective number of degrees of freedom is often not large enough to apply the coverage factor equal to 2.


The coverage factor corresponding to a confidence level of 95% is defined as . Individual values are given in table.E.5.

The expanded uncertainty is determined by the following equation:

. (E. 7)

E. 5 Example

In the present example, the measurement uncertainty is calculated for the arithmetic mean values of the sample stage 3, selected from some of the test material. The results given in table.E.2 were obtained on a pendulum Koper, which successfully passed both direct and indirect validation. In the first step calculated the average observed value , i.e. , standard uncertainty values , i.e. , which is determined by the formula (E. 3).


Table E. 2 — Results of Charpy test

in joules

The result of the test
, sample 1	105,8
, sample 2	109,3
, sample 3	112,3
The average value	109,1
Standard standard deviation of the values for 3	3,2
The standard uncertainty of the obtained values ,calculated according to equation E. 3	1,9

In the second step, the original results were combined with the results of the last indirect verification of the testing machine, using specimens with different levels of energy (e.g., 20 joules, 120 joules 220 joules). The level of absorbed energy of the test material was closest to the level of 120 j (109,1 j). Therefore, uncertainty estimates were used the results of indirect testing at this energy level. The value of the bias has met the criteria according to ISO 148−2. Due to the lack of reliable evidence of stability in the measured value was corrected for systematic error. Therefore, the obtained value , i.e., considered equal to the average value according to the measurements, ie .

Since the correction for systematic error was not introduced, the uncertainty calculation was carried out with contributions . The standard uncertainty of the result of indirect testing at 120 j amounted to 5.2 j with the number of degrees of freedom equal to 7 (see ISO 148−2). These insights and values can be obtained from a calibration certificate or verification of used pendulum.

In table E. 3 shows the procedure for the calculation of measurement uncertainty.


Table E. 3 — Diagram of the calculation of the expanded uncertainty of measurement

The result of the original test		The result of indirect testing at 120 j
	1,9 J.		5,2 j
The number of degrees of freedomwhen testing 3 samples, defined as	2	The number of degrees of freedom taken from the certificate of calibration or indirect verification of the machine	7
Combined standard uncertainty calculated according to formula (E. 5),			5,5 j
the effective number of degrees of freedom taken from the formula (E. 6)			8
The coefficient corresponding to 8 and the confidence level of 95%,			2,3
The expanded uncertainty			12,6 j

For the preparation of a report on the results of testing and uncertainty of measurement can be used table E. 4.


Table E. 4 — Summary table of results of measurement with an expanded uncertainty of measurement

-	J.	J.	-	-	J.
3	3,2	109,1	8	2,3	12,6
This standard deviation represents the collective assessment of the test material (in its value also includes a contribution from the convergence measurement device, which cannot be assessed separately). The expanded uncertainty, calculated according to this procedure corresponds to a confidence level of approximately 95%. Given the uncertainty depends on the uncertainty of the test temperature, which was measured with an uncertainty equal to 2K (the confidence level -95%. Given uncertainty does not take into account contributions that may be made by those or other concrete characteristics of the material being tested.

Table E. 5 — Values quantiles of student’s distribution for degrees of freedom , at confidence probability of 95% [3].

The number of degrees of freedom,	for 95%
1	Of 12.71
2	4,30
3	3,18
4	Of 2.78
5	2,57
6	2,45
7	2,36
8	2,31
9	2,26
10	Of 2.23
11	2,20
12	2,18
13	Of 2.16
14	2,14
15	2,13
16	2,12
17	2,11
18	2,10
19	Of 2.09
20	Of 2.09
25	Of 2.06
30	2,04
25	2,03
40	2,02
45	2,01
50	2,01
100	1,98
	1,96

App YES (reference). Information about the compliance of the referenced international standards (and acting in this capacity interstate standards), national standards of the Russian Federation

App YES
(reference)

Table YES

Marking the reference international standard	The degree of compliance	Designation and name of the relevant national standard
ISO 148−2:2008	-	*
ISO 148−3:2008	-	*
ISO 286−1:2010	-	*
ISO 3785:2006	-	*
ISO 556:2006	-	*
ASTM E 23−96	-	*
* The corresponding national standard is missing. Prior to its adoption, it is recommended to use the translation into Russian language of this international standard. The translation of this international standard is the Federal information Fund of technical regulations and standards

Bibliography

[1]	ISO 3785, Metallic materials — Designation of test specimen axes in relation to product texture (ISO 3785, metallic Materials. Marking the axes of the test specimens relative to the texture of the product)*
[2]	ISO 14556, Steel — Charpy V-notch pendulum impact test — Instrumented test method (ISO 14556, Steel. The test impact strength Charpy specimens with a V-shaped incision. Instrumental test method)*
[3]	ASTM E 23, Standard Test Methods for Notched Bar Impact Testing of Metallic Materials (ASTM E 23, Metallic materials. Standard methods of testing the impact strength when using notched specimens)*
[4]	Nanstad R. K., Swain. R. L. Berggeren. R. G. Influence of Thermal Conditioning Media on Charpy Specimen Test Temperature, «Charpy Impact Test: Factors and Variables» (the influence of the environment temperature exposure to the test temperature of the Charpy sample. «The test for impact strength Charpy. Factors and variables», ASTM STP 1072, ASTM, 1990, p. 195)*
[5]	ISO/IEC 98−3, Propagation de distributions par une de Monte Carlo ISO/IEC 98−3, Guide to the measurement Uncertainty. Part 3: Guide to the expression of uncertainty in measurement (GUM:1995)*

_______________
* Official translation of this standard is the Federal information Fund of technical regulations and standards

UDC 669.01:620.174:006.354	OKS 77.080
Key words: metal materials, testing, impact strength, pendulum KOPR, Sharpie

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M.: STANDARTINFORM, 2014