This standard applies to the inclined Y-groove weld crack test of carbon steel and low alloy steel welded joints. GB/T 4675.1-1984 Weldability test inclined Y-groove weld crack test method GB/T4675.1-1984 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Weldability testing
Method of Y-groove cracking testThis standard applies to the Y-groove cracking test of carbon steel and low alloy steel welded joints. 1 Nouns and terms
UDC 621.791.053
.66: 620.192
GB 4675.1-84
Automatic welding apparatus with covered electrode: an electrode feeding device that can feed the electrode at a certain angle and speed according to the requirements of the welding process and can control the electrode feeding method and welding specifications. 2 Preparation of test pieces
2.1 Test materials
In principle, the test materials are steels that meet the following standards: GB700-79 "Technical conditions for ordinary carbon structural steel"; GB711-65 "Technical conditions for high-quality carbon structural steel, hot-rolled steel plates", GB712--80 "Technical conditions for structural steel for shipbuilding"; GB713-72 "Technical conditions for carbon steel and ordinary low-alloy steel plates for boiler manufacturing"; YB13-69 "Steel grades and general technical conditions for ordinary low-alloy structural steel" YB175~63 "Technical conditions for hot-rolled thick steel plates of ordinary carbon steel and low-alloy steel" and YB536-69 "Technical conditions for hot-rolled thick plates of carbon steel and ordinary low-alloy steel for pressure vessels". 2.2 Shape and size of test pieces
The shape and size of the test pieces are shown in Figure 1.
2.3 The groove of the test piece is machined by mechanical cutting. Issued by the National Bureau of Standards on July 28, 1984
Implemented on May 1, 1985
3 Test conditions
Constrained weld
Test weld
GB 4675.184
Constrained weld
Figure 1 Shape and size of test piece
3.1 In principle, the welding rods used in the test shall be the welding rods listed in GB981-76 "Welding rods for low carbon steel and low alloy high strength steel", which shall match the test steel.
3.2 The welding rods shall be strictly dried before welding.
3.3 The restrained weld shall be welded on both sides, and care shall be taken not to cause angular deformation and incomplete penetration. 3.4 After the test piece reaches the test temperature, the test weld shall be welded in accordance with the standard specifications in principle. 4 Test steps
4.1 Assemble the test piece according to Figure 1.
4.2 Welding of restrained welds.
4.3 Welding of test welds
4.3.1 When manual welding is used, the test welds shall be welded as shown in Figure 2. When welding is carried out using an automatic electrode feeding device, the welding shall be carried out as shown in Figure 3. 4.3.2
Test welds
D Low Low
Constrained welds
Constrained welds
Figure 2 Position of test welds when manual welding is used
GB 4675.1-84
Arc starting point
Test welds
Constrained welds
Constrained welds
Figure 3 Position of test welds welded using an automatic electrode feeding device 4.4 The crack detection and dissection of the welded specimens shall be started 48 hours after welding. 5 Calculation method
5.1 Use the naked eye or other appropriate methods to check whether there are cracks on the surface and cross section of the welded joint, and calculate the surface crack rate, root crack rate and cross section crack rate respectively. 5.2 The length or height of the crack shall be tested as shown in Figure 4. The crack length is in the shape of a curve. As shown in Figure 4a, it is tested according to the straight line length. When the crack is repeated, it is not necessary to calculate separately.
Surface crack
bRoot crack
Figure 4 Calculation of crack length of specimen
5.3 Calculate the surface crack rate using the following formula: Where Ct—
-surface crack rate, %,
>li--sum of surface crack length, mm,
Cross section crack
（1）
L——test weld length, mm.
5.4 After the specimen is colored by an appropriate method, it is pulled or bent apart, and then the root crack is detected according to Figure 4, and the root crack rate is calculated according to the following formula.
Wherein: Cr—-root crack rate, %
L—test weld length, mm,
Elr—sum of root crack lengths, mm.
5.5 Carry out cross-sectional crack inspection on the five cross sections of the specimen, measure the crack height according to the requirements of Figure 4c, calculate the crack rate of the five cross sections respectively by the following formula, and then find the average value. H.
x ​​100%:
Wherein: Cs—section crack rate, %;
H—minimum thickness of the sample weld, mm, H—height of the cross-sectional crack, mm.
The positions of the five cross sections are determined by dividing the distance between the test weld width uniformity and the center of the weld arc crater into four equal parts. 6 Records
6.1 Test date, time, ambient temperature and humidity. 6.2 Test piece steel grade and chemical composition, test piece state, test piece thickness and rolling direction. 6.3 Test piece temperature before welding, type of welding power supply, welding polarity, welding rod brand, welding rod diameter, welding rod drying temperature and time, welding current, welding voltage and welding speed. 6.4 Time and method for starting dissection of the test piece.
6.5 Test results: crack length and crack rate. 83
A.1 Scope of application
GB4675.1—84
Appendix A
Explanation of "Test method for cracks of inclined Y-groove welding" (supplement)
The cracks generated by this test method mostly appear in the heat-affected zone at the tip of the weld root. When the crack resistance of the weld metal is poor, the crack may extend to the weld metal and even penetrate the weld surface. The crack may appear immediately after welding, or it may start to appear after several minutes or even hours. Therefore, this test method is mainly suitable for cold crack tests in the heat-affected zone of steel welded joints, and can also be used as a crack test for the combination of parent metal and welding rod.
A.2 Preparation of test pieces
A.2.1 The thickness of the test piece is not limited, and the commonly used thickness is 9~38mm. A.2.2 In order to avoid problems such as fluctuations in the gap between the test pieces and the hardened layer of the gas cutting surface, the groove processing adopts mechanical cutting. A.3 Test conditions
A.3.1 The restraint weld of the test piece is shown in the figure below, and an X-shaped groove is opened. A plug slightly larger than 2mm is inserted into the welding test part to ensure the gap between the test pieces, and the plug is removed after the restraint weld is welded. The quality of spot welding on both sides of the test plate must be strictly guaranteed. Honey sheet
Test weld groove
Constraint weld groove shape
A.3.2 Constraint weld welding: Generally, a low-hydrogen electrode with a diameter of 4 or 5 mm is used. First, weld the first layer from the back, and then weld the first layer on the front side. Be careful not to produce angular deformation and incomplete penetration. The following layers are welded alternately on the front and back sides until the welding is completed. A.3.3 Before welding the test weld, the spatter attached to the restraint weld should be cleaned, and water droplets, oil, rust, etc. should be removed. To this end, first use an appropriate heating method to remove surface water droplets and grease. After sufficient cooling, use a wire brush or sandpaper to grind the groove to remove rust, and finally wash it with ketone.
A, 3.4 The test is generally carried out at room temperature, and can also be carried out under various preheating and heat treatment conditions. In order to further increase the sensitivity of cracks, the test piece can be precooled to a temperature below zero, or half of the test piece can be immersed in water for welding.
A.3.5 When welding the test weld by manual welding, the arc must be struck outside the groove, and the arc must also be extinguished away from the groove. When welding with an automatic electrode feeding device, the arc should be struck and extinguished inside the test groove. A.4 Test steps
A.4.1 Surface cracks should be inspected by naked eye observation or other appropriate methods, preferably magnetic powder or staining methods. Cross-section crack detection requires grinding and corrosion of the cross section to be tested for cracks. Ordinary steel is corroded with 5% nitric acid alcohol solution, and it is especially recommended to use 3% picric acid alcohol solution plus 3% concentrated sulfuric acid corrosion, and then use a microscope with a magnification of 20 to 30 times to detect cracks. A.4.2 The test specimen shall not be cut from the test plate by gas cutting. Mechanical cutting shall be used to avoid crack extension caused by cutting vibration.
A.5 Calculation method
GB 4675.1-84
A.5.1 The cracks at the arc initiation and arc termination of the weld seam depend to a large extent on the welder's skills. Such cracks may extend into the test weld seam. To avoid misjudgment of the crack sensitivity of steel and welding rod, the arc initiation and arc termination shall be performed outside the groove when welding the test weld seam by manual arc welding (as shown in Figure 2).
When welding with an automatic electrode feeding device, the calculation of the crack rate shall include the cracks generated at the arc initiation and arc termination, but the thermal cracks at the arc termination shall be excluded.
A.5.2 When welding the test weld seam by an automatic electrode feeding device, the root crack rate in the test weld seam can be calculated from the cross-sectional crack inspection results as follows: Root cracks are detected on each cross section of the arc initiation and arc termination part of the test weld seam, and each is calculated as 17% of the crack rate. The root crack rates on the three cross sections in the central part of the weld seam are each calculated as 22% of the crack rate. The sum of the crack rates of the five cross sections calculated in this way is the root crack rate. www.bzxz.net
A.5.3 The cross-sectional crack rate can also be calculated by the following method. That is: the test weld is colored by appropriate means, and then the specimen is pulled or bent. At this time, the cross-sectional crack rate is expressed as a percentage of the ratio of the crack area on the broken cross section to the total cross-sectional area. GB4675.1-—84
Appendix B
Test specification
(reference)
In order to compare the cold crack tendency of different steel grades, the following test specifications are recommended: Welding rod diameter
Welding current
Welding voltage
Welding speed
Additional instructions:
170±10A?
24±2Vs
150±10mm/min.
This standard is equivalent to the 1981 edition of Japanese standard JIS Z3158-1966 "Oblique Y-type crack test method". This standard was proposed by the Ministry of Machinery Industry of the People's Republic of China. This standard was started by Harbin Welding Research Institute. The main drafters of this standard are Yu Jilun, Guo Shoufen and Cui Fengchi.
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