GOST 12004-81
GOST 12004−81 Steel reinforcement. Methods of tensile tests (with Amendments No. 1, 2)
GOST 12004−81
Group B09
INTERSTATE STANDARD
CASE HARDENING STEELS
Test methods tensile
Reinforcing-bar steel. Tensile test methods
ISS 77.140.15
AXTU 1909
Date of introduction 1983−07−01
INFORMATION DATA
1. DEVELOPED AND INTRODUCED by the Ministry of metallurgy of the USSR
2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for standards from
3. REPLACE GOST 12004−66
4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS
| The designation of the reference document referenced |
The number of the paragraph, subparagraph |
| GOST 166−89 |
1.8 |
| GOST 427−75 |
1.9 |
| GOST 1497−84 |
1.1; 2.1; 3.1; 3.4; 3.7.3 |
| GOST 6507−90 |
1.8 |
| GOST 29329−92 |
1.9 |
5. Limitation of actions taken by Protocol No. 5−94 of the Interstate Council for standardization, Metrology and certification (ICS 11−12−94)
6. EDITION (Sept 2009) with Changes No. 1, 2 approved in June 1985, August 1990 (IUS 9−85, 11−90)
This standard specifies the methods of tensile tests at a temperature of (20) °C reinforcement steel with nominal diameters from 3.0 up to 80 mm (wire rods and reinforcing ropes) round and periodic profile, designed for conventional reinforcement and prestressed concrete structures to determine mechanical properties:
full of the elongation at maximum load;
elongation after rupture;
relative uniform elongation after rupture;
after narrowing the relative gap;
temporary resistance;
yield strength (physical);
the limits of fluidity and elasticity (conditional);
modulus of elasticity (initial).
Terms, symbols and definitions are given in Appendix 1.
1. SAMPLING METHODS
1.1. For tensile tests used samples of rebar round or periodic profile with rough surface nominal diameter from 3.0 mm to 80 mm. allowed for testing of specimens hot-rolled rod of rebar with a nominal diameter greater than 20 mm on trimmed samples of cylindrical shape with the heads is possible with preservation of the heads on the surface of the rental. The shape, size and processing requirements of the working part of the samples according to GOST 1497.
Grind the sample should be so that the longitudinal axis of the stud and sample were parallel. When stem diameter up to 40 mm inclusive to the longitudinal axis of the rod and the sample can be the same, when the diameter of the rods 45 to 60 mm and 70 to 80 mm distance from the axis of the rod to the axis of the specimen shall be respectively 1/8 and ¼ (Fig.1).
|
|
|
Damn.1
(Changed edition, Rev. N 2).
1.2. Allowed before the test to edit sample smooth pressure or light hammer blows on the model, lying on the lining. The lining and the hammer should be of softer material than the sample.
The inadmissibility of changes of samples should be specified in the NTD of reinforcing steel.
1.3. The total length of the sample valves selected depending on the working length of the sample and design of the grip of the testing machine.
The working length of the sample shall be:
for the sample with nominal diameter up to 20 mm inclusive — not less than 200 mm;
for the sample with nominal diameter exceeding 20 mm — not less than 10;
for reinforcement of ropes of all diameters of not less than 350 mm.
The initial gauge length for the samples of rod of rebar and wire must be installed according to normative-technical documentation for finished products and for samples of the reinforcing cables shall be 300 mm.
(Changed edition, Rev. N 1, 2).
1.4. The initial cross-sectional area of the raw samples of rebar periodic profile , in mm
, calculated by the formula
where is the mass of test sample, kg;
— length of test sample, m;
— the density of steel, 7850 kg/m
.
1.5. For squared and round specimens of rebar nominal diameter of from 3.0 to 40.0 mm determine the cross-sectional area measurement of the diameter along the length of the sample in three sections: in the middle and at the ends of the working length; in each section in two mutually perpendicular directions. The cross-sectional area of the sample calculated as the simple average of these six measurements.
1.6. The cross-sectional area of the rope is defined as the sum of the cross-sectional areas of individual wires comprising the rope.
Allowed to use the nominal cross-sectional area of the ropes specified in the normative-technical documentation on the ropes.
(Changed edition, Rev. N 1).
1.7. The initial estimated length is measured with an accuracy of 0.5 mm.
1.8. Diameters of round and machined rebar specimens with a nominal diameter of from 3.0 to 40.0 mm measured by Vernier caliper according to GOST 166 or micrometer according to GOST 6507.
1.9. Mass of test specimens of reinforcement periodic profile with a nominal diameter of less than 10 mm is determined with an error of not more than 1.0 g samples of rebar with diameter from 10 to 20 mm with an error of not more than 2.0 g, and samples with a diameter of over 20 mm with an error of less than 1% of the mass of the sample.
Samples of reinforcing steel weighed on the scales according to GOST 29329*, and the length of the sample is measured with a metal ruler according to GOST 427.
_______________
* On the territory of the Russian Federation the document is not valid. Valid GOST R 53228−2008. — Note the manufacturer’s database.
2. EQUIPMENT
2.1. Used machines of all systems subject to their conformity with the requirements of this standard and GOST 1497.
2.2. When testing requirements should be observed:
a reliable centering of the sample;
the smoothness of loading;
the average loading rate during the test to yield stress shall not be more than 10 N/mm(1 kgf/mm
) per second; beyond the yield point the loading rate may be increased so that the speed of the movable capturing machine did not exceed 0.1 of the working length of the test sample per minute; scale siloizmeritelya the test machine should not exceed five times the expected value of the highest load
for the test sample valves;
the design of the grips of the testing machine shall ensure that no rotation of the ends of the rope around the axis of the sample.
2.3. The measuring instruments must meet the requirements of this standard and the other NTD.
2.4. In determining the conditional limits of elasticity and yield strength with strain gauge of the relative length scale of the strain gauge should not exceed:
0,005% of the base strain gauge in the determination ;
0.05% of base strain gauge in determining the .
3. TESTING AND PROCESSING OF RESULTS
3.1. The value of relative elongation , %, is calculated by the formula
Depending on the size of the initial estimated length of the sample added to the letter index. For example, if the initial calculated length equal to 5, —
, at 100 mm
, etc.
Peeled samples for determination of elongation — according to GOST 1497.
3.1.1. The final calculated length of the sample , including the location of its gap, is determined in the following way.
Before the test, the sample length, more of the working length of the sample, is marked in equal parts with labels applied dividing machine, braces or a core. The distance between the labels for fittings with a diameter of 10 mm or more should not exceed the amount
to be a multiple of 10 mm. For valves with a diameter of less than 10 mm distance between the marks shall be equal to 10 mm. is allowed at the layout samples distance between marks to take more than 10 mm and exceeding the value
, but not more than the value of the initial estimated length
.
If the number of intervals corresponding to the initial length of the sample, is a fraction, it is rounded up to a whole in a big way.
After the test part of the specimen carefully stacked together, placing them in a straight line. From the gap in one direction delay /2 intervals and put a label
. If the value of
/2 is fractional, it is rounded up to whole numbers in a big way. The section from the break to the first mark in this case is taken as the whole interval.
From the label lay in the direction of open
intervals and put a label
(hell.2). Cut
equal-received in the gap of the final design length
.
Damn.2
Damn.3
If the fracture is closer to the edge of the capture of the machine than the value /2 (Fig.3), obtained after breaking the final estimated length
is determined as follows:
from the gap to the extreme label from capture to determine the number of intervals that is referred to
/2. From the point
to the rupture site delay
intervals and put a label
. Then from the label
lay
/2 —
/2 intervals and put a label
.
The final estimated length of sample , mm, is calculated by the formula
where and
— respectively the length of the sample between points
and
and
and
.
If the fracture is at a distance from the capture of less than the length of the two intervals or 0.3for samples with diameters less than 10 mm, the magnitude of the calculated length cannot be reliably determined and repeat the test.
(Changed the wording. Izm. N 2).
3.2. The final calculated length of the sample of reinforcing ropes are determined using the strain gauges hung on rope lines or special equipment, allowing to measure the specimen deformation until fracture. Before installing the strain gauge, rulers or other devices to the sample apply an initial load equal to 0,1% — 0,15% of the expected breaking strength.
(Added, Rev. N 1).
3.2. Relative uniform elongation is determined in all cases outside the area of the gap in the initial design of the length equal to 50 or 100 mm. the distance from the gap to the nearest label the initial estimated length for fittings with a diameter of 10 mm or more should not be less than 3
and more than 5
, a rebar with a diameter of less than 10 mm from 30 to 50 mm.
3.2.1. To determine the relative uniform elongation of the final design length
is determined by tags (see the devil.2 and 3).
The value of relative uniform elongation , %, is calculated by the formula
3.2.2. The final calculated length and
measured with an accuracy of 0.5 mm.
3.2.3. Relative elongation and relative uniform elongation after fracture calculated with rounding up to 0.5%. The shares to 0.25% discarded, and fractions of 0.25% and taking more than 0.5%.
3.3. The total relative elongation at maximum load can be determined by one of methods:
with the aid of strain gauges or other special devices which can measure the specimen strain up to the failure;
the summation of residual deformation after fracture of the specimen with elastic deformation at the maximum load by the formula
3.4. The relative constriction after rupture determined on round samples of wire and rod reinforcement as well as on grinded samples of cylindrical shape in accordance with the requirements of GOST 1497.
3.5. Tensile strength , N/mm
(kgf/mm
), calculated with the error not more than 5 N/mm
(0.5 kgf/mm
) formula
3.6. Yield strength , N/mm
(kgf/mm
), calculated with the error not more than 5 N/mm
(0.5 kgf/mm
) formula
3.7. Apparent yield stress determined on the basis of the tolerance
on conditionally instantaneous plastic deformation equal to 0.02% to 0.1% of the estimated length of the strain gauge, inclusive. While the letter
added index corresponding to the accepted tolerance
. For example, if the tolerance is 0.05%, the apparent yield stress is denoted by
, etc.
3.7.1. Conditional limits of elasticity and fluidity can be determined by analytical and graphical methods.
The strain gauge on the sample set after application of the initial load corresponding to 0.05 to 0.10 the expected values of temporary resistance .
When testing of reinforcing ropes previously spend not less than twice the loading — unloading in the interval 0,1−0,35 expected breaking strength.
The load is applied is equal to or proportional stages so that the load corresponding to the desired limit, there were at least 8−10 stages of loading, starting from the initial load.
Upon reaching the total load, corresponding to 0,7−0,9 desired limit, it is recommended to reduce the size of the step of loading two or four times.
Exposure at constant loading at each stage of loading, excluding the time of load application should be no more than 10 seconds.
3.7.2. Yield strength is determined by the analytical method. Calculate the amount of residual deformation
for a single load step, based on the value of the average deformation was found at various stages of loading in the range of 0.10 to 0.40 of an alleged effort corresponding to the yield strength, and for reinforcing ropes in the range of 0,10−0,40 strength.
The load at which there is equality
in N/mm
(kgf/mm
), which is calculated with an error of not more than 5 N/mm
(0.5 kgf/mm
) formula
Conditional limits of elasticity are determined in the same manner: calculate the amount of residual deformation, for example, equal to
at one stage, determine the load
corresponding to the elongation
Apparent yield stress , N/mm
(kgf/mm
), calculated with the error not more than 5 N/mm
(0.5 kgf/mm
) formula
3.7.3. Graphic method of determining the relative limits of fluidity and elasticity, building tension diagram «load-elongation». Y-axis aside the load, and the abscissa shows the corresponding elongation (Fig.4).
Damn.4
The chart is a direct parallel to the plot proportional to 
When you define the conditional yield strength and yield point graphically chart the tension 
Allowed the definition of the conditional yield strength in the machine diagram the churchyard 1497 with periodic control tests using strain gauges.
The amount, frequency and method of testing should be established according to normative-technical documentation for finished products.
Examples of determining the relative limits of elasticity and yield strength are given in appendices 2 and 3.
(Changed edition, Rev. N 2).
3.8. For rods and wire, the initial modulus of elasticity equal to the ratio of the increment of voltage in the range from 0.1 to 0.35 to the relative elongation of the sample in the same interval of loading.
Initial modulus is determined with an error of less than 1% according to the formula
In the interval from 0.1 to 0.35must be at least three successive stages of loading.
3.8.1. For reinforcing ropes initial modulus of elasticity is determined by the formula p. 3.8 after double loading and razrusheniya in the interval 0,1 and 0,35.
3.9. The testing result is accepted, the mechanical properties obtained from testing each sample. The number of test samples indicated in the specifications and technical documentation for reinforcing steel.
3.10. The test results are not taken into account in the following cases:
when breaking the sample by applying the label, if any characterization of the mechanical properties by its size does not meet the requirements;
at break of the specimen in the grips of the testing machine;
when errors are detected in testing or recording test results.
ANNEX 1 (reference). TERMS, SYMBOLS AND DEFINITIONS
ANNEX 1
Reference
| The term | The symbol |
Unit | Definition |
| 1. The nominal diameter of the sample | mm | Rod rebar is equal to the nominal diameter of equal-sized cross-sectional area of round rods; | |
| for drawing the hardened rod of reinforcing steel equal to the nominal diameter of the bars to their hood; | |||
| for reinforcing wire is equal to the nominal diameter of the wire before applying a periodic profile; | |||
| for reinforcing ropes equal to their nominal diameter | |||
| 2. The initial cross-sectional area of sample |
mm |
The cross-sectional area of the specimen to the testing | |
| 3. The working length of the sample |
mm | Part of the sample between the clamping devices of the testing machine | |
| 3A. The initial gauge length | mm | The gauge length before testing, the sample on the basis of which is carried out measurement of elongation | |
| 4. Full length sample |
mm | The sample length equal to the working length plus a plot to secure the rods to the grips | |
| 5. The final calculated length |
mm | The gauge length, measured after the specimen fractures at the site, including the fracture | |
| 6. The final calculated length, not including the fracture |
mm | The gauge length, measured after the specimen fractures at the site, not including the fracture | |
| 7. The gauge length for strain gauge |
mm | The area of the working length of the sample, equal to the base strain gauge | |
| 8. Axial tensile load |
N (kgf) | The load acting on the specimen at the moment of testing | |
| 9. Voltage |
N/mm |
The voltage determined by the ratio of the load | |
| 10. The total relative elongation at maximum load | % | The ratio of the increment of the estimated length of the specimen, determined at the beginning of the decline of the highest load prior to failure to the initial calculated length, expressed in percent of the initial estimated length of the | |
| 11. Elongation after rupture |
% | The ratio of the increment of the calculated length of a specimen in which there was a gap, to the initial calculated length, expressed in percent of the initial estimated length of the | |
| 12. Relative uniform elongation after fracture | % | The ratio of the increment of the calculated length of the sample after rupture at the site that does not include a place of rupture, to the initial calculated length, expressed in percent of the initial estimated length of the | |
| 13. The relative narrowing of the gap after | % | The ratio of the difference between the initial and the minimum cross-sectional areas of the sample after the break to the initial cross-sectional area, expressed as a percentage | |
| 14. Temporary resistance | N/mm (kgf/mm |
The voltage corresponding to the highest load | |
| 15. Yield strength (physical) | N/mm (kgf/mm |
Voltage corresponding to the smallest load | |
| 16. The limit of elasticity (conditional) | N/mm (kgf/mm |
The voltage at which conditionally instantaneous plastic deformation reaches a predetermined value the estimated length of the strain gauge | |
| 17. Yield strength (conditional) | N/mm (kgf/mm |
The voltage at which conditionally instantaneous plastic deformation reaches 0.2% of the estimated length of the strain gauge | |
| 18. The modulus of elasticity (initial) | N/mm (kgf/mm |
The ratio of the increment of voltage to the corresponding increment of elastic strain at the initial stage of loading |
APPENDIX 1. (Changed edition, Rev. N 1).
APPENDIX 2 (recommended). EXAMPLE OF DETERMINATION OF YIELD POINT AND OF THE CONDITIONAL YIELD STRENGTH ROD FOR REBAR AND WIRE
ANNEX 2
Recommended
EXAMPLE OF DETERMINATION OF YIELD POINT AND OF THE CONDITIONAL YIELD STRENGTH
ROD FOR REBAR AND WIRE
1. Analytical method
1.1. Sample hot-rolled reinforcing steel of grade A-IV of the periodic profile with a nominal diameter of 14 mm. total length of specimen 400 mm. the Initial cross-sectional area of 150 mm
.
1.2. The test is carried out with strain gauges measuring the deformation at two diametrically opposite edges of the sample. Base one strain gauge 100 mm, and the sum of the bases of the two strain gauges 2
200 mm.
1.3. The amount of residual deformation in the determination of the conditional yield strength, 0.2% of the total base strain gauges or 0.4 mm with a length of 200 mm, the Amount of residual deformation in determining the limit of elasticity equal to 0.02% of the total base, or 0.04 mm strain gauges with a length of 200 mm.
1.4. On the sample after it is installed into the grips of the testing machine is applied initial load equal to 1000 kg, which is approximately 0,08. Install strain gauges and conduct a further loading of the sample by steps of 1000 kg to 7000 kg, which is 0.7
, and below 500 kg to the overall elongation of the sample of the order of 1.0%, which in this case corresponds to the load of 11500 kg.
The results of the measurements of loads and strains recorded in the table of tests (see table).
As can be seen from the table, in the range from 1000 to 4000 kg single phase loads of 1000 kg corresponds to a total deformation of 6 x 10 mm. the Definition of conditional limits of elasticity and of the conditional yield strength of the analytical method is carried out using the data given in the table.
| Room p/p | Load |
The scale reading of the strain gauge, mm |
The total deformation |
The increment of strain in one phase of 10 |
Elastic deformation |
Conditionally instantaneous deformation | |
| left |
right | ||||||
| 1 |
9800 (1000) | 0 | 0 | 0 | 0 | 0 | 0 |
| 2 |
19600 (2000) | 2,5 | 3,0 | 5,5 | 5,5 | 6,0 | 0,5 |
| 3 |
29400 (3000) | 6,0 | 6,0 | 12,0 | 6,5 | 12,0 | 0 |
| 4 |
39200 (4000) | 9,0 | 9,0 | 18,0 | 6,0 | 18,0 | 0 |
| 5 |
49000 (5000) | 12,0 | 12,0 | 24,0 | 6,0 | 24,0 | 0 |
| 6 |
58800 (6000) | 15,0 | 15,0 | 30,0 | 6,0 | 30,0 | 0 |
| 7 |
68600 (7000) | 18,0 | 18,0 | 36,0 | 6,0 | 36,0 | 0 |
| 8 |
73500 (7500) | 20,0 | 19,0 | 39,0 | 3,0 | 39,0 | 0 |
| 9 |
78400 (8000) | 22,0 | 21,0 | 43,0 | 4,0 | 42,0 | 1,0 |
| 10 |
83300 (8500) | 24,0 | 23,5 | 47,5 | 4,5 | 45,0 | 2,5 |
| 11 |
88200 (9000) | 26,5 | 25,5 | 52,0 | 4,5 | 48,0 | 4,0 |
| 12 |
93100 (9500) | 28,0 | 29,0 | 57,0 | 5,0 | 51,0 | 6,0 |
| 13 |
98000 (10000) | 37,0 | 40,0 | 77,0 | 20,0 | 54,0 | 23,0 |
| 14 |
102900 (10500) | 52,0 | 55,0 | 107,0 | 30,0 | 57,0 | 50,0 |
| 15 |
107800 (11000) | 74,0 | 77,0 | 151,0 | 44,0 | 60,0 | 91,0 |
| 16 |
112700 (11500) | 98,0 | 102,0 | 200,0 | 49,0 | 63,0 | 137,0 |
| 17 |
117600 (12000) | - | - | - | - | - | - |
mm
mm
, mm
According to experience, the amount of residual deformation of 0.04 mm corresponds to a load of 9000 kg, i.e., 
.
The amount of residual deformation corresponding to conventional yield strength, which in this case is 0.4, or 40·10mm.
As can be seen from the table, the amount of residual deformation of 0.4 mm was somewhat higher than the amount of deformation at a load of 10000 kgf and smaller than 
determined by interpolation
.
2. The graphical method
2.1. According to the measurements of deformations are given in the table build a chart 
(see the devil.4). On the chart, conduct a direct parallel to the plot proportional chart
and
corresponding to the conventional yield stress,
and elasticity
.
69,0 kg/mm
;
.
APPENDIX 3 (recommended). AN EXAMPLE OF THE DEFINITION OF THE CONDITIONAL YIELD STRENGTH OF THE REINFORCING ROPES. ANALYTICAL METHOD
APPENDIX 3
Recommended
Analytical method
1. The test sample of the rope with a nominal diameter of 15 mm and an initial cross-sectional area of 141.6 mm. Measure the deformation with strain gauges in two diametrically opposite sides of the sample. The scale interval of 0.01 mm. Base strain gauge strain gauge 300 mm. the Tolerance on the amount of residual deformation in the determination of the conditional yield strength of 0.2% of the strain gauge 300 mm is 0.6 mm. Given that the measurement of strain produced on two sides of the sample, twice the specified deviation will be 0. 6x2=1.2 mm.
2. To test the sample after it is installed into the grips of the testing machine applied the initial load of 2000 kgf, which corresponds to about 0.1 of the expected breaking strength 
. Then the sample is loaded from 0.10 to 0.35
of one step of loading, from 0.35 to 0.8
at least seven steps. The results of the measurements of loads and strains at each stage of loading are recorded in the table.
Next is the processing of the readings of the strain gauges.
Load |
The scale reading of the strain gauge, mm | The sum of the counts for the two strain gauges 10 |
Total deformation |
Elastic deformation |
Conditionally instantaneous plastic deformation | |
| left | right | |||||
| 19600 (2000) |
8 | 7 | 15 | 0 | 0 | 0 |
| 78400 (8000) |
72 | 68 | 140 | 125 | 125 | 0 |
| 19600 (2000) |
8 | 7 | 15 | 0 | 0 | 0 |
| 78400 (8000) |
68 | 67 | 135 | 120 | 120 | 0 |
| 19600 (2000) |
8 | 7 | 15 | 0 | 0 | 0 |
| 39200 (4000) |
28 | 27 | 55 | 40 | 40 | 0 |
| 58800 (6000) |
48 | 47 | 95 | 80 | 80 | 0 |
| 78400 (8000) |
68 | 67 | 135 | 120 | 120 | 0 |
| 98000 (10000) |
88 | 87 | 175 | 160 | 160 | 0 |
| 117600 (12000) |
108 | 107 | 215 | 200 | 200 | 0 |
| 127200 (14000) |
127 | 128 | 255 | 240 | 240 | 0 |
| 137000 (15000) |
141 | 140 | 281 | 266 | 260 | 6 |
| 146800 (16000) |
154 | 154 | 308 | 293 | 280 | 13 |
| 150600 (17000) |
168 | 168 | 336 | 321 | 300 | 21 |
| 160400 (18000) |
185 | 184 | 369 | 354 | 320 | 34 |
| 170200 (19000) |
203 | 202 | 405 | 390 | 340 | 50 |
| 175100 (19500) |
217 | 218 | 435 | 420 | 350 | 70 |
| 184900 (20000) |
230 | 230 | 460 | 445 | 360 | 85 |
| 194700 (20500) |
254 | 253 | 507 | 492 | 370 | 122 |
| 204500 (21000) |
293 | 293 | 586 | 571 | 380 | 191 |
, 103. A predetermined deviation from a proportional relationship between the stress and strain a few more are obtained when the load 20500 kgs and less than load 20000 kgs.
So determined by interpolation
.
