Test method for evaluating hydrogen embrittlement resistance of metal material

Abstract

The invention discloses a test method for evaluating hydrogen embrittlement resistance of a metal material. The test method comprises the following steps: (1) designing a stress applying device; the stress applying device comprises a main body, a bolt and a silica gel gasket; screw holes are formed in the bottom of the main body; the top of the main body is of a semi-open structure; (2) placing a metal material sample on the silica gel gasket on the bolt, then rotating the bolt to enable the metal material sample to be in contact with the silica gel gasket on the lower edge of the top, and then placing and fixing a zinc sheet in the center of the metal material sample; and (3) continuously rotating the bolt for 1-5 screw pitches to enable the metal material sample to be in a bent state, then soaking the whole device in an acidic corrosion medium until the metal material sample is fractured, and evaluating the hydrogen embrittlement resistance of the metal material according to the fracture time. The evaluation test method is simple in structure, easy and convenient to operate and especially suitable for evaluating the hydrogen embrittlement resistance of the working roll of the galvanizing temper mill, and the industry blank is filled up.

Description

Technical Field

[0001] The invention belongs to the technical field of metal material performance testing, and in particular relates to a test method for evaluating the hydrogen embrittlement resistance of metal materials. Background Art

[0002] During the smelting process, forged steel rolls are likely to produce serious defects such as gas, inclusions, segregation, looseness, and various structural inhomogeneities, and these defects are difficult to remove in the subsequent forging process. Therefore, large forgings such as forged steel rolls often have uneven chemical composition, various structural defects, and harmful gases of different types but excessively high content. Among these harmful gases, hydrogen is the most harmful and can easily cause the "hydrogen embrittlement" phenomenon. Hydrogen embrittlement refers to the phenomenon that hydrogen adsorbs and desorbs on the metal surface, and some hydrogen enters the interior of the metal material and continues to diffuse. After hydrogen enters the steel, the plasticity and toughness of the steel are reduced. Its sensitivity changes with the change of strain rate during loading.

[0003] The galvanized skin pass mill is a complete set of rolling mill equipment for surface flattening and rolling of cold-rolled galvanized strips. Its working roll is a key component of the rolling mill and plays a key role in the operation of the rolling mill. In addition to the residual hydrogen in the smelting process, due to the characteristics of the zinc element in the environment, it is very easy to react chemically with acidic or alkaline liquids in the environment to generate hydrogen. Due to the corrosion of hydrogen on the roller material, hydrogen corrosion microcracks are easily generated. Under the action of rolling force, the roller is prone to cracking and failure. The generated hydrogen is adsorbed and penetrated into the inside of the roller. The accumulation of hydrogen gradually produces stress concentration, which causes hydrogen embrittlement cracks, affects the service life of the roller, and eventually leads to accidents such as peeling.

[0004] At present, there are many test methods for evaluating the hydrogen embrittlement resistance of metal materials. However, on the one hand, many test methods are complex in structure and cumbersome in operation, and some even have safety hazards. On the other hand, the existing test methods are not suitable for evaluating the hydrogen embrittlement resistance of galvanized leveler working rolls. Summary of the invention

[0005] The purpose of the present invention is to solve the above problems and provide a test method for evaluating the hydrogen embrittlement resistance of metal materials which has a simple structure, is easy to operate and has a good effect.

[0006] The technical solution to achieve the purpose of the present invention is: a test method for evaluating the hydrogen embrittlement resistance of metal materials, comprising the following steps: ① Design a stress applying device; the stress applying device includes a main body, a bolt and a silicone gasket; the main body includes a bottom, a side and a top; the bottom of the main body is provided with a screw hole; the top of the main body is a semi-open structure; the bolt is connected to the main body through the screw hole at the bottom; the silicone gasket is respectively arranged on the lower edge of the top and the bolt.

[0007] ② Place the metal sample on the silicone gasket on the bolt, then rotate the bolt so that the metal sample contacts the silicone gasket at the bottom edge of the top, and then place a zinc sheet in the center of the metal sample and fix it.

[0008] ③ Continue to rotate the bolt for 1 to 5 pitches to make the metal material sample bend, then immerse the entire device in an acidic corrosive medium until the metal material sample breaks, and evaluate the hydrogen embrittlement resistance of the metal material based on the fracture time.

[0009] In the above step ②, the metal material sample is in the form of a sheet with a length of 80 to 120 mm, a width of 8 to 12 mm, and a height of 0.8 to 1.2 mm.

[0010] In the above step ②, the zinc sheet is in sheet shape, with a length of 3 to 7 mm, a width of 3 to 7 mm, and a height of 0.8 to 1.2 mm.

[0011] The present invention has the positive effects: (1) The present invention uses sheet metal materials for testing, which is not only convenient to cut, but also can be used to place a zinc sheet in the middle of the sheet metal material, and then tighten the bolts to form a simply supported beam, and then place it in an acidic corrosive medium, so that the metal material sample is simultaneously subjected to the combined effects of bending force and corrosive medium. In this way, cracks or even fractures will appear after a period of time, and the hydrogen embrittlement resistance of the metal material can be evaluated based on the fracture time.

[0012] (2) The evaluation test method of the present invention has a simple structure and is easy to operate. It is particularly suitable for evaluating the hydrogen embrittlement resistance of the working roll of a galvanized skin-pass mill, thus filling a gap in the industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic structural diagram of the stress applying device of the present invention.

[0014] Figure 2 for Figure 1 Left view of .

[0015] Figure 3 This is a schematic diagram of the structure of the experimental process of step ② in Example 1.

[0016] Figure 4 Schematic diagram of the structure of the experimental process of step ③ in Example 1. DETAILED DESCRIPTION

[0017] (Example 1) The test method for evaluating the hydrogen embrittlement resistance of metal materials in this embodiment is as follows: ① Design a stress applying device.

[0018] See also Figure 1 and Figure 2 The stress applying device of this embodiment includes a main body 1, a bolt 2 and a silicone gasket 3.

[0019] The main body 1 includes a bottom portion 11 , a side portion 12 and a top portion 13 .

[0020] The bottom 11 of the main body 1 is provided with screw holes, and the top 13 of the main body 1 is a semi-open structure.

[0021] The bolt 2 is connected to the main body 1 through the screw hole of the bottom 11; the present embodiment adopts M16 bolt.

[0022] The silicone gasket 3 is respectively arranged on the lower edge of the top 13 and the bolt 2 .

[0023] ②See Figure 3 , place the sheet metal sample 4 on the silicone gasket 3 on the bolt 2, and then rotate the bolt 2 to make the sheet metal sample 4 contact with the silicone gasket 3 at the lower edge of the top 13, and then place a zinc sheet 5 in the center of the metal sample 4 and fix it with tape.

[0024] The sheet metal material sample 4 used in this embodiment is made of BSH1, and has dimensions of 100 mm (length)×10 mm (width)×1 mm (height).

[0025] The size of the zinc sheet 5 used in this embodiment is 5 mm (length)×5 mm (width)×1 mm (height).

[0026] ③See Figure 4 , the bolt 2 is further rotated by 2 pitches (equivalent to 4 mm) to make the sheet metal material sample 4 bent, and then the entire device is immersed in sulfuric acid solution. As a result, the sheet metal material sample 4 breaks after 64 hours.

[0027] (Example 2 to Example 9) The test methods of each embodiment are basically the same as those of embodiment 1, except for the material of the sheet metal material sample in step ② and the pitch of the rotation in step ③. The specific results are shown in Table 1.

[0028] Table 1 Sample material Number of rotation pitches Break time Example 1 BSH1 2, 4mm 64h Example 2 BSH1 3, 6mm 46h Example 3 BSH1 4, 8mm 27h Example 4 MC5A 2, 4mm 86h Example 5 MC5A 3, 6mm 67h Example 6 MC5A 4, 8mm 51h Example 7 MC3A 2, 4mm 120h without breakage Example 8 MC3A 3, 6mm 105h Example 9 MC3A 4, 8mm 90h

[0029] In Table 1, the composition of each material is shown in Table 2.

[0030] Table 2 BSH1 MC5A MC3A C 0.70～0.75% 0.77～0.84% 0.82～0.90% Si 0.80～1.00% 0.40～0.60% 0.30～0.50% Mn 0.25～0.45% 0.20～0.50% 0.20～0.45% Cr 4.80～5.20% 5.00～5.40% 2.80～3.20% Ni ≤0.25% 0.30～0.50% 0.60～0.80% Mo 1.00～1.20% 0.30～0.50% 0.20～0.40% V 0.40～0.60% 0.10～0.20% 0.05～0.15% P ≤0.020% ≤0.020% ≤0.020% S ≤0.015% ≤0.015% ≤0.015%

[0031] It can be seen from Table 1 and Table 2 that material MC3A has the best hydrogen embrittlement resistance, followed by MC5A, and BSH1 is the worst.

[0032] The main reason for hydrogen embrittlement of the working roll of the galvanized leveler is that the surface of the roll is in contact with the zinc alloy, and there is water or acidic or alkaline leveling liquid in the use environment, which forms a galvanic cell reaction with the carbide inside the roll to produce hydrogen, which may cause hydrogen embrittlement.

[0033] Therefore, the more alloy content in the working roll material, the more carbides there will be and the worse the hydrogen embrittlement resistance will be.

[0034] Among the three materials, BSH1 alloy has the highest content, the most carbides, and the worst hydrogen embrittlement resistance; MC3A alloy has the lowest content, the least carbides, and the best hydrogen embrittlement resistance, which is completely consistent with the evaluation method of the present invention, indicating that the evaluation method of the present invention has better results.

Claims

1. A test method for evaluating the hydrogen embrittlement resistance of metal materials, characterized in that The following steps are involved: ① Design a stress application device; The stress applying device comprises a main body (1), a bolt (2) and a silicone gasket (3); The main body (1) comprises a bottom (11), a side (12) and a top (13); the bottom (11) of the main body (1) is provided with a screw hole; the top (13) of the main body (1) is a semi-open structure; The bolt (2) is connected to the main body (1) via a screw hole in the bottom (11); The silicone gasket (3) is respectively arranged on the lower edge of the top (13) and on the bolt (2); ② Place the metal material sample (4) on the silicone gasket (3) on the bolt (2), then rotate the bolt (2) to make the metal material sample (4) contact the silicone gasket (3) at the lower edge of the top (13), and then place a zinc sheet (5) in the center of the metal material sample (4) and fix it; ③ The bolt (2) is continuously rotated for 1 to 5 pitches to make the metal material sample (4) bend, and then the entire device is immersed in an acidic corrosive medium until the metal material sample (4) breaks, and the hydrogen embrittlement resistance of the metal material is evaluated according to the breaking time.

2. The test method for evaluating the hydrogen embrittlement resistance of metal materials according to claim 1, characterized in that: The metal material sample (4) is in the form of a sheet, with a length of 80 to 120 mm, a width of 8 to 12 mm, and a height of 0.8 to 1.2 mm.

3. The test method for evaluating the hydrogen embrittlement resistance of metal materials according to claim 1, characterized in that: The zinc sheet (5) is in sheet shape, with a length of 3 to 7 mm, a width of 3 to 7 mm, and a height of 0.8 to 1.2 mm.

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