Method for improving mechanical property of medium-manganese steel welding joint

A technology for welding joints and manganese steel, which is applied in the field of medium manganese steel welding process and manganese steel welding process, can solve the problems of high alloy content, complete interface fracture, high cost, etc., achieve simple equipment conditions, improve solder joint strength, and improve toughness Effect

Inactive Publication Date: 2019-03-22
SHANGHAI UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The first generation of steel for automobiles includes dual-phase steel (DP), low-alloy high-strength steel (HSLA), etc., and its strength-plastic product is generally 10-30GPa·%. The use of steel can no longer meet the requirements of automobile crashworthiness, so the second generation of automobile steel has been developed
The second generation of steel for automobiles is mainly twinning induced plasticity steel (TWIP) and Q&P steel, which has excellent crashworthiness performance, but due to its high alloy content and difficult metallurgical process, the cost is high
After the pulse is over, it is cooled at high speed under the action of electrodes, and the brittle martensite is mainly formed in the nugget. When a low load is applied to it, it is easy to fail in the form of complete interface fracture, showing poor welding performance.
At present, the method of forming a multi-layer nugget by welding medium manganese steel has not been reported in the literature.

Method used

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  • Method for improving mechanical property of medium-manganese steel welding joint
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  • Method for improving mechanical property of medium-manganese steel welding joint

Examples

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Effect test

Embodiment 1

[0031] In this example, see Figure 1 ~ Figure 3 , a method for improving the mechanical properties of medium manganese steel welded joints, for medium manganese steel steel, applying a resistance spot welding process that can form an inner layer nugget, thereby obtaining a multilayer molten nugget with two or more layers of nuggets Nuclear solder joints, the steps are as follows:

[0032]a. Select medium manganese steel plates with a thickness of 1.4 mm and a mass fraction of manganese element of 7% for resistance spot welding of the same steel, pre-treat the medium manganese steels that need to be welded, and clean the surface of the medium manganese steels. Obtain clean welding base metal;

[0033] b. Use a resistance spot welding machine with a voltage of 380V to closely contact the clean welding base metal that has been cleaned in step a, place the position of the welding base metal that needs to be welded under the electrode, and use the electrode as the clamp Clamping...

Embodiment 2

[0042] This embodiment is basically the same as Embodiment 1, especially in that:

[0043] In this embodiment, a method for improving the mechanical properties of medium manganese steel welded joints, for medium manganese steel, applying a resistance spot welding process that can form an inner layer nugget, so as to obtain a nugget with two or more layers Form multi-layer nugget solder joints, the steps are as follows:

[0044] a. Choose medium manganese steel plates with a thickness of 1.4mm and manganese element mass fractions of 7% and 10% respectively for resistance spot welding of dissimilar steels, and pre-treat the medium manganese steels to be welded. Clean up to get a clean welding base metal;

[0045] b. Use a resistance spot welding machine with a voltage of 380V to closely contact the clean welding base metal that has been cleaned in step a, place the position of the welding base metal that needs to be welded under the electrode, and use the electrode as the clamp...

Embodiment 3

[0050] This embodiment is basically the same as the previous embodiment, and the special features are:

[0051] In this example, see Figure 4 , a method for improving the mechanical properties of medium manganese steel welded joints, for medium manganese steel steel, applying a resistance spot welding process that can form an inner layer nugget, so as to obtain a multilayer molten nugget with two or more layers of nuggets Nuclear solder joints, the steps are as follows:

[0052] a. This step is the same as in Embodiment 1;

[0053] b. This step is the same as in Embodiment 1;

[0054] c. This step is the same as in Embodiment 1;

[0055]d. After the solder joint cooling process in the step c ends, keep the pressure on the end of the electrode, and immediately apply an additional pulse current through the electrode, the pulse of the additional pulse current is a single pulse or multiple current values ​​are equal or unequal Pulse, the control additional pulse current value...

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Abstract

The invention provides a method for improving a mechanical property of a medium-manganese steel welding joint. An additional pulse method capable of generating inner-layer nuggets is added after the pulse which is mainly used for connection is utilized, medium-manganese steel with the manganese element mass fraction of 4-13% can obtain two or more layers of nuggets at a welding point, and thus thepurpose of improving the joint strength of the welding spot is achieved. Compared with a traditional welding process which only obtains the single-layer nugget, after two or more layers of nuggets are formed, the grain shape in the original nuggets is changed, and the structure in the original nuggets and the heat affected zone changes, so that multiple structures exist at the same zone at the same time, and thus cracks can be better prevented from expanding; and therefore, under the occasion that the requirement for the joint strength is high, the welding process capable of forming the inner-layer nuggets has more application potential.

Description

technical field [0001] The invention relates to a manganese steel welding process, in particular to a medium manganese steel welding process, which is applied in the field of advanced iron and steel materials and welding technology. Background technique [0002] In recent years, air pollution has become more serious and the greenhouse effect has intensified. In the automotive industry, lightweight methods are used to reduce energy consumption, save oil resources and reduce pollutant emissions. Therefore, researchers have developed various high-strength steels for use in the automotive industry. The first generation of steel for automobiles includes dual-phase steel (DP), low-alloy high-strength steel (HSLA), etc., and its strength-plastic product is generally 10-30GPa·%. Steel has been unable to meet the crashworthiness requirements of automobiles, so the second generation of automobile steel has been developed. The second-generation automotive steels are mainly twinning-in...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B23K11/11B23K11/34
CPCB23K11/11B23K11/34
Inventor 高玉来王远方丁凯赵炳戈张元恒
Owner SHANGHAI UNIV
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