High-strength steel differential stable austenitic friction stir welding method and welding joint

A friction stir and welding method technology, applied in the field of metal plastic processing, can solve the problems of large welding torque and forward resistance, large plastic deformation and heat input, difficult to meet application requirements, etc., so as to reduce the time cost and reduce the heat affected zone. , The effect of improving the utilization rate of welding efficiency

Active Publication Date: 2021-12-17
XI'AN UNIVERSITY OF ARCHITECTURE AND TECHNOLOGY
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AI Technical Summary

Problems solved by technology

The following problems exist in the conventional FSW welding of TRIP high-strength steel: 1. The temperature is distributed along the gradient in the horizontal direction, and the uniformity of the structure is poor; 2. The shaft shoulder and the stirring needle are integrated, and the plastic deformation and heat input are large, resulting in the loss of retained austenite; 3. 1. The cooling rate after welding is high, and the distribution of carbon elements is difficult; 4. The welding torque and forward resistance are large, and the energy consumption is high
Brittle martensite is easily formed in the weld area, which inhibits the TRIP / TWIP effect, making the joint less plastic and difficult to meet application requirements

Method used

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  • High-strength steel differential stable austenitic friction stir welding method and welding joint
  • High-strength steel differential stable austenitic friction stir welding method and welding joint
  • High-strength steel differential stable austenitic friction stir welding method and welding joint

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Experimental program
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Effect test

Embodiment 1

[0068] This embodiment provides a high-strength steel differential stable Austrian friction stir welding method, including heating the high-strength steel for the first heat preservation, and then using the shoulder and stirring to perform rotary friction stir welding on the high-strength steel, Then cool to holding temperature, carry out second holding temperature, then cool to room temperature;

[0069] The shaft shoulder and the stirring pin rotate independently, and the rotational friction stir welding includes the same direction or reverse differential rotational friction stir welding.

[0070] Specifically include:

[0071] Step 1: heat the high-strength steel for the first heat preservation, the temperature of the first heat preservation is 50°C-600°C, and the heat preservation time is 15-30s; the purpose is to preheat the welding plate, so that the welding process Reduced pressing force while improving weld formability.

[0072] Step 2: Rotating friction stir welding...

Embodiment 2

[0085] The difference between this embodiment and Embodiment 1 is that this embodiment welds QP980 steel with a thickness of 1.8mm, the length of the stirring needle is 1.5mm, the rotation speed is 400rpm, the rotation speed of the shoulder is 400rpm, and the reduction is 0.2mm. The forward speed is 200mm / min.

[0086] The first holding temperature is 400°C, and the holding time is 15s. The second holding temperature is 350°C, and the holding time is 10 minutes. According to the carbon constraint quasi-equilibrium theory, the holding temperatures are 400°C and 350°C. The first heat preservation is equivalent to the preheating effect before FSW welding. The second heat preservation is to achieve element distribution, in order to avoid the formation of martensite, let C partition into austenite.

[0087] After testing, the residual austenite content of the obtained welded joint is about 2.7% ( Figure 5 , 6 ).

Embodiment 3

[0093] This embodiment is the same as Embodiment 2, except that the material is QP1180 steel, the stirring needle is 1.6 mm long, the rotation speed is 400 rpm, the shaft shoulder rotation speed is 350 rpm, the reduction is 0.2 mm, and the forward speed is 150 mm / min.

[0094]The first holding temperature is 450°C, holding time is 25s, the second holding temperature is 500°C, holding time is 10min, the residual austenite content of the obtained welded joint is about 1.6%.

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Abstract

The invention discloses a high-strength steel differential stable austenitic friction stir welding method and a welding joint. The method comprises the following steps of carrying out first-time heat preservation on high-strength steel, welding the high-strength steel by adopting a differential friction stir welding technology, carrying out second-time heat preservation, and then cooling to room temperature, wherein according to differential friction stir welding, rotating friction stir welding is conducted on the high-strength steel through different shaft shoulders and stirring needles which rotate independently in the same direction or in the opposite directions. Compared with a conventional friction stir welding technology, the differential friction stir welding technology can improve the uniformity of a joint structure, increase the content of retained austenite and improve the mechanical property of the welding joint.

Description

technical field [0001] The invention belongs to the field of metal plastic processing, and in particular relates to a high-strength steel differential stability Austrian friction stir welding method and a welded joint. Background technique [0002] The automobile industry is the pillar industry of the developed countries such as Europe, America, Japan and South Korea and the national economy of our country. With the rapid development of the automobile industry, the problems of environmental pollution and energy shortage have become increasingly prominent. Reducing fuel consumption and tail gas emissions has become an urgent problem to be solved in the automotive industry. In order to realize the lightweight of automobiles, it has become a development trend to replace traditional low-strength steels with advanced high-strength steels. As a representative of the third generation of advanced high-strength steel, transformation-induced plasticity (Transformation-induced plasti...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B23K20/12B23K20/26
CPCB23K20/1255B23K20/26
Inventor 乔柯王快社王文张婷王佳郝政扬蔡军佟立波
Owner XI'AN UNIVERSITY OF ARCHITECTURE AND TECHNOLOGY
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