GOST 23240-78
GOST 23240−78 welded Construction. A method for the assessment of brittle fracture in reaction to a welding arc burn (with Change No. 1)
GOST 23240−78
Group B09
STATE STANDARD OF THE USSR
CONSTRUCTION WELDED
A method for the assessment of brittle fracture in reaction to a welding arc burn
Welding structure. Method of estimation the brittie failure by reaction
on arc welding burn
Period of validity from 01.01.1980
before 01.01.1985*
_______________________________
* Expiration removed by Protocol No. 7−95
The interstate Council for standardization,
Metrology and certification (I & C N 11, 1995). -
Note the manufacturer’s database.
DEVELOPED by the Ministry of Railways of the USSR (CLAIMS)
Zam. Director M. M. krajcik Ph. D.
Supervisor V. P. Kotelnikov Ph. D.
The Executor V. S. Kuznetsov
INTRODUCED by the Ministry of Railways of the USSR
Zam. Minister A. F. Tan
The APPROVAL AND INTRODUCTION of the Decree of the USSR state Committee on standards of 9 August 1978, N 2150
The Change N 1, approved and put into effect by the Decree of the USSR State Committee for standards from
Change No. 1 made by the manufacturer of the database in the text IUS N 9, 1989
This standard specifies a method of evaluating the cold resistance of steels of welded structures by the reaction of a burn arc.
The essence of the method consists in receiving on the sample surface maloplastichnyj lens under the action of the arc burn and determine the degree of its influence on the tendency of steel to the transition to the brittle state under shock loading.
The standard applies to research and experimental work.
(Changed edition, Rev. N 1).
1. SAMPLING METHOD
1.1. Samples with burn manufactured in two types:
I — of steel of a thickness of 10 mm or more;
II — steel thickness 6 to 10 mm.
The dimensions of the samples of the I type shown in hell.1, type II — on features.2.
Damn.1. Type I
Type I
Damn.1
Damn.2. Type II
Type II
Damn.2
Lens of the burn is in the middle of the sample.
1.2. The number of samples for tests is specified in normative and technical documentation for steel or of welded construction. In the absence of such instructions the test is performed not less than 3 samples at the same temperature.
1.3. Place cutting blanks for the samples and their orientation relative to the direction of rolling shall be taken in accordance with normative-technical documentation for steel or welded construction.
1.4. When cutting workpieces must be taken, to prevent a possible change in the properties of the metal due to heating or cold working.
(Changed edition, Rev. N 1).
2. EQUIPMENT
Apparatus for application of a burn on the sample (see recommended application) is to ensure the stability of the process of applying burns and sufficient reproducibility; the ability to control the time of existence arising from the welding arc at the time of application of a burn on the sample. Installation can be made in the form of attachment to existing sources of welding current or as a separate unit with a counter power source, have a clamp ammeter to monitor the magnitude of the short-circuit current and a voltmeter to monitor the voltage of idling.
3. PREPARING FOR THE TEST
3.1. The surface of the sample, is intended to cause burns should be brushed. It is not allowed the presence of traces of corrosion and coolants after machining.
3.2. Other faces of the sample is allowed to handle the gouge along the length of the sample or milling without further grinding. Allowed to produce samples in which one or two faces perpendicular to the surface of a burn have of rolling a crust.
3.3. Before testing, the specimens having two side faces with rolling a crust, is measurement of each test sample with an error of less than ±0.1 mm.
3.4. Causing burns on the sample is carried out by electrode (without coating) with a diameter of 3 mm, made of welding wire brand SV-08A under GOST 2246−70. The wire should be degreased and should not have corrosion. In determining the sensitivity of steels to burn electrode for a specific welding conditions allowed to inflict burns on a sample with electrodes made from welding wire other brands, which is used for welding of concrete structures.
3.5. When changing electrodes, the end of the new electrode is sharpened to a cone with an angle at the vertex 60 to 90° before applying the burns on samples upravlyaut by applying 4−5 trial burns.
3.6. For the application of burns in the sample is direct current reverse polarity when the short-circuit current of 250 A.
3.7. The lens diameter of the burn should be 4±0.2 mm.
3.8. The stamp shall be affixed on the end or on the sides of the sample, or on the opposite side of the burn, at a distance of not more than 15 mm from the end, but not on the surface.
(Changed edition, Rev. N 1).
3.9. The plane, which are stacked samples with the burn when branding, you must have the recess that at the time of the marking of the sample relied only on the end parts and the middle part with the lens of the burn was above the notch.
4. TESTING
4.1. Sample tests with the concentrate in the form of a burn arc (O) is carried out according to GOST 9454−78.
(Changed edition, Rev. N 1).
4.2. During the test the pendulum impact is applied from the side opposite to the lens burn.
4.3. The tests are carried out at temperatures as specified in normative and technical documentation for steel or of welded construction. If there are no such instructions, the tests are carried out at normal temperature and at temperatures minus 20, minus 40, minus 70 °C. is allowed to conduct testing only at one temperature to determine compliance with previously established standards.
4.4. Work with a kick sample with a burn (TO) determine on a scale of pendulum.
(Added, Rev. N 1).
5. PROCESSING OF THE RESULTS
5.1. The toughness of samples with burn (), j/cm
(kgf/cm
), calculated according to the formula
where is the job of the shock spent on fracture of the sample, j (kgf·m);
the cross — sectional area of the sample, determined in the middle part of it, without taking into account the topography of the burn before tests, cm
.
The calculation is carried out with an accuracy of 1 j/cm
(0.1 kgf·m/cm
).
(Changed edition, Rev. N 1).
5.2. The test results of samples of different types are not comparable.
5.3. For the evaluation criterion of dbtt () is taken such that is specified in normative and technical documentation for steel or of welded construction. In the absence of such a criterion for the critical temperature of brittleness should be taken that at which impact strength of at least one sample equal to or less than 30 j/cm
(3 kgf·m/cm
) for samples of type I and, respectively, 40 j/cm
(4 kg·m/cm
) for samples of type II.
(Changed edition, Rev. N 1).
5.4. Inspection results are entered into the Protocol which indicates the sequence number of samples brand of the welding wire, the temperature of the test, diameter, burn, fracture toughness of each sample.
APPLICATION (recommended). SETTING TO OBTAIN A STABLE BURN ELECTRODE
APP
Recommended
Installation (see figure 3) consists of elektrogerate special design with the drive, the clips of a fuse, test equipment and power source of the welding arc.
Elektrodvigatel 4 moves in the guides 7, mounted on panel 13 and connected at the top plate 19 with adjusting screw 8, limiting the lift of the electrode 2, which provides the necessary clearance between the electrode and the sample 1.
Elektrodvigatel with the electrode is driven by electromagnet 12 when the button 14 through duplici lever 11 which at one end enters the window 20 and can move it vertically. On the set lever switch 10 for closing the welding circuit. In initial position elektrodvigatel and the lever return springs 9 and 18. The spring 9 serves to move the electrode to the sample 1. Bottom position is set by the screw 17. The force with which the electrode is pressed against the sample, is governed by the spring 5, is inserted in the coupling collar 6. The screw 3 is provided an electrode.
Cartridge 16 ensures that the opening of the welding circuit. It is included in the welding circuit in series with the power source 15 and the electrode.
The use of a fuse as the element limiting value of the welding current and the duration of the welding arc, provides getting the same burns. A thermal fuse may be different in the cross section and chemical composition of the wire, providing for the burning time of the arc 0,04 obtaining the sample burns with a diameter of 4±0.2 mm.
It is recommended to use fusible insert of copper wire in diameter of 0,4 mm.
To determine the burning time of the arc welding process applying an arc burn is recorded on an oscilloscope.
