This standard is applicable to manual arc welding and is a test method for relatively evaluating the cold cracking tendency of steel based on the maximum hardness of the heat affected zone. GB/T 4675.5-1984 Weldability test Test method for maximum hardness of the heat affected zone of welding GB/T4675.5-1984 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Weldability testing
Testing method of maximum hardnessin weld heat -affected zone
UDC: 821.791.06 !
: 820.178.152
GB 4675.5--84
This standard is applicable to manual arc welding and is a test method for relatively evaluating the cold cracking tendency of steel based on the maximum hardness of the heat-affected zone. Preparation of test pieces
1.1 The shape and size of the test pieces refer to Figure 1 and Table 1 respectively. The standard thickness of the test piece is 20mm. If the plate thickness exceeds 20mm, it must be machined to 20mm thick and retain a rolled surface. If the plate thickness is less than 20mm, it must be processed. Test section
Hardness test specimen
Test specimen name
Test specimen No. 1bZxz.net
Test specimen No. 2
Test specimens can be cut by gas cutting.
Test conditions
Surface preparation
Figure 1 Test specimen shape
Table 1 Test specimen dimensions
125±10
125±10
2.1 Before welding, appropriate methods should be adopted to remove water, oil, rust and excessively thick oxide scale on the surface of the test specimen that are harmful to welding. 2.2 In principle, the welding rod should be suitable for the test specimen to be welded, with a diameter of 4mm. 2.3 During welding, the test specimens should be supported at both ends and sufficient space should be left under the test specimens. 2.4 Test specimen No. 1 was welded at room temperature, and test specimen No. 2 was welded at preheating temperature. Issued by the National Bureau of Standards on July 28, 1984
Implemented on May 1, 1985
GB 4675.5--84
2.5 As shown in Figure 1, a weld with a length of 125±10mm is welded along the center line of the rolled surface of the test piece. 2.6 The test weld is welded in the flat welding position. 2.7 The welding specifications are as follows in principle:
Welding current 170±10A, welding speed 150+10mm/min. zBAfter welding, the test piece is cooled naturally in still air without any heat treatment. 3 Determination of hardness
3.1 At least 12 hours must pass after welding before the sample for hardness measurement can be taken, and the hardness should be tested as soon as possible after taking it. 3.2 At room temperature, cut the middle of the weld vertically by mechanical processing as shown in Figure 1, and then take the measurement sample on this section. When cutting, it must be processed while cooling to prevent the hardness of the weld heat affected zone from decreasing due to the increase of the section temperature. 3.8 The test surface of the hardness measurement sample is ground and then corroded. Then, as shown in Figure 2, draw a straight line that cuts the tangent point Q at the bottom of the fusion line and is parallel to the rolled surface of the test plate. On this straight line, the Vickers hardness is measured at room temperature and a load of 10kg every 0.5mm. The tangent point ○ and more than 7 points on both sides are used as hardness measurement points. 3.4 Other matters related to the hardness measurement test shall be in accordance with the provisions of YB53-64 "Metal Vickers Hardness Test Method". Weld metal
Rolled surface
4 Record
4.1 Test date, time and ambient temperature. Tangent point
Fusion line
Hardness measurement line
Figure 2 Hardness detection position
4.2 Specimen steel grade and chemical composition, specimen state, and rolling direction. 4.8 Specimen temperature before welding, type of welding power source, welding polarity, welding rod brand, welding rod diameter, welding rod drying temperature and time, welding current, welding voltage and welding speed. 4.4 Position of all measurement points and their hardness values. 103
A. Preparation of specimens
GB4675.5--84
Appendix A
Explanation of "Test method for maximum hardness of welding heat affected zone" (supplement)
In view of the fact that when welding under preheating conditions, due to the relationship of heat diffusion, the smaller the specimen size, the harder the value will be. Therefore, it is stipulated that the specimen size used for welding under preheating conditions is larger than the specimen size used for welding at room temperature. A.2 Test conditions
A.2.1 The arc voltage is not specified in the welding conditions because the influence of the arc voltage on the maximum hardness can be ignored within the actual welding arc voltage range.
A, 2.2 The welding current is specified in the allowable range of 170±10A for the commonly used 4mm diameter welding rod. The welding speed is specified as 150±10mm/min. When the type of welding rod is different or the welding rod diameter is not 4mm, if this standard is cited, it is hoped that the ratio of the selected welding current (A) and welding speed (mm/min) is 170 to 150. In this way, the same maximum hardness can be obtained as the welding conditions specified in 2.7. A.3 Determination of hardness
A.3.1 The maximum hardness reflects the aging phenomenon when the sample is placed at room temperature after welding. That is, in the first few hours, the hardness increases to a certain extent, reaches the maximum value after about 10h, and then tends to decrease slightly. Therefore, the specimens for hardness measurement are required to be sampled 12 hours after welding, and the hardness should be measured as quickly as possible. A.3.2 Under no circumstances shall tempering color be allowed to appear on the test surface of the specimen when the specimen is mechanically cut or ground with a grinding wheel.
The spacing between the two hardness measurement points is specified to be 0.5mm, which is slightly too small and contradicts the provisions of YB53-64 "Metal Vickers Hardness Test Method". However, due to the narrow width of the maximum hardness zone in the welding heat affected zone, it is necessary to measure at a spacing of 0.5mm. Additional Note:
This standard is equivalent to the 1981 edition of the Japanese standard JIS Z3101-1976 "Test Method for Maximum Hardness of Welding Heat Affected Zone". This standard was proposed by the Ministry of Machinery Industry of the People's Republic of China. This standard was drafted by Harbin Welding Research Institute. The main drafters of this standard are Yu Jilun, Guo Shoufen, and Cui Fengchi. 104
Tip: This standard content only shows part of the intercepted content of the complete standard. If you need the complete standard, please go to the top to download the complete standard document for free.