Resistance spot welding method matched for matching of steel plate containing super-strong thermal forming

A resistance spot welding and super heat technology, applied in resistance welding equipment, welding equipment, metal processing equipment, etc., can solve the problems of low tensile strength, difficult to meet the requirements of mass production in the automotive industry, and difficult to accurately control the current, etc. To achieve the effect of improving joint performance

Pending Publication Date: 2021-05-28
SHANGHAI INST OF OPTICS & FINE MECHANICS CHINESE ACAD OF SCI +1
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  • Application Information

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Problems solved by technology

[0004] Patent 1 "A Resistance Spot Welding Process for 1800MPa Class Ultra-High-Strength Thermoformed Steel Plates" (publication number: CN110548976A) has obtained a spot-welded joint with good connection between ultra-high-strength thermoformed steel plates, but the process must pass through the surface of the plate to be welded The processes of pickling, oxide layer grinding, acetone cleaning and welding are complicated and have a long cycle, which is difficult to meet the large-volume and fast-paced production requirements of the automotive industry;
[0005] Patent 2 "Spot welding method for high-strength steel plates with excellent joint strength" (Patent No.: CN104661784B) obtains reliable welding between high-strength steels with a tensile strength of 780-1850 MPa by strictly controlling the current between the two-stage pulses, but the The tensile strength of the welded plate is lower than 1850MPa, which cannot solve the welding of hot-formed steel plates with a tensile strength greater than 1850MPa;
[0006] Patent 3 "Resistance Spot Welding Method" (Patent No.: CN105792977B) and "Resistance Spot Welding Method" (Publication No.: CN107848061A) realize the connection of plates by strictly coordinating and controlling the current amplitude and welding pressure amplitude in different welding stages respectively , the former needs to determine the moment of applying the current according to the thickness of the plate, while the latter needs to change the welding pressure during the application of the welding pulse. Wide application of this method

Method used

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  • Resistance spot welding method matched for matching of steel plate containing super-strong thermal forming
  • Resistance spot welding method matched for matching of steel plate containing super-strong thermal forming
  • Resistance spot welding method matched for matching of steel plate containing super-strong thermal forming

Examples

Experimental program
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Effect test

Embodiment 1

[0053] The material to be welded is PHS2000 bare steel plate with a thickness of 1.4mm, and its tensile strength is higher than 2000MPa. s The welding pulse is 200ms, the number of welding pulses is 1, and the welding process uses a servo welding gun. The welding method includes the following steps:

[0054] 1) On the basis of the single-pulse welding test, the critical spatter current I of double-layer PHS2000 single-pulse welding is obtained 0 , is 9kA, so the current amplitude I of the welding pulse w =I w1 =(0.7~0.98)×I 0 =6.3~8.82kA, take 8.8kA, pulse duration t w = 200ms;

[0055] 2) The current amplitude I of the preheating pulse p =(0.1~0.9)I w1 =0.88~7.92kA, take 6kA, pulse duration t p = t w = 200ms;

[0056] 3) The current amplitude I of the tempering pulse t =(0.3~1)I w =2.64~8.8kA, take 8.8kA, pulse duration t t = t p = t w = 200ms;

[0057] 4) The cooling time t between each pulse c0 , t c1 Take the same value, both are 20ms;

[0058] 5) Durati...

Embodiment 2

[0061] The material to be welded is PHS2000 bare steel plate with a thickness of 1.4mm, its tensile strength is higher than 2000MPa, and the match to be welded is a three-layer plate, the electrode pressure P is 6kN, and the preloading time is t s The welding pulse is 200ms, the number of welding pulses is 2, and the welding process uses a servo welding gun.

[0062] 1) On the basis of the single-pulse welding test, the critical spatter current I of three-layer PHS2000 single-pulse welding is obtained 0 , is 11.5kA, so the current amplitude I of the first pulse in the welding stage w1 =(0.7~0.98)×I 0 =8.05~11.27kA, take 11kA, set the current amplitude I of the second pulse w2 =I w1 =11kA, the pulse duration is taken as t w = 180ms;

[0063] 2) The current amplitude I of the preheating pulse p =(0.1~0.9)I w1 =1.1~9.9kA, take 9kA, pulse duration t p = t w = 180ms;

[0064] 3) The current amplitude I of the tempering pulse t =(0.3~1)I w2 =3.3~11kA, take 11kA, pulse du...

Embodiment 3

[0069] The material to be welded is 1.4mm thick PHS2000 steel plate with Al-Si coating, its tensile strength is higher than 2000MPa, the matching is a double-layer plate to be welded, the electrode pressure is 5kN, and the pre-pressing time is t s The welding pulse is 200ms, the number of welding pulses is 1, and the welding process uses a servo welding gun.

[0070] 1) On the basis of the single-pulse welding test, the critical splash current I of PHS2000 single-pulse welding with double-layer Al-Si coating is obtained 0 , is 8.2kA, so the current amplitude I of the welding pulse w =I w1 =(0.7~0.98)×I 0 =5.74~8.036kA, take 7.3kA, pulse duration t w = 200ms;

[0071] 2) The current amplitude I of the preheating pulse p =(0.1~0.9)I w1 =0.73~6.57kA, take 5kA, pulse duration t p = t w = 200ms;

[0072] 3) The current amplitude I of the tempering pulse t =(0.3~1)I w1 =2.19~7.3kA, take 7.3kA, pulse duration t t = t p = t w = 200ms;

[0073] 4) The cooling time t betw...

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Abstract

The invention discloses a resistance spot welding method for matching of a steel plate containing super-strong thermal forming. The method comprises the following steps: 1) a correspondingly matched critical splash current I0 is found out on the basis of matching of super-strong thermal forming steel by adopting monopulse welding; 2) welding pulse parameters are determined according to the number j of matched steel plates to be welded, wherein j is an integer 2 or above; and 3) an intermediate frequency direct current spot welder is adopted to conduct welding according to the determined parameters and the time sequence of pre-pressing, preheating, welding, tempering and pressure maintaining. According to the resistance spot welding method, the welding nugget with the large enough diameter can be stably formed on the basis that obvious welding defects are not generated, a welding process window larger than 1.5 kA (an existing window generally does not exceed 0.5 kA, and a process window needed by actual production is larger than 1 kA) is obtained, and the joint strength is obviously improved (the tensile-shear strength is larger than 21 kN, and an existing process joint does not exceed 16 kN).

Description

technical field [0001] The invention relates to super-strength thermoforming steel, in particular to a resistance spot welding method with super-strength thermoforming steel plate matching. Especially when the materials to be welded include hot-formed steel plates with a tensile strength above 1500 MPa, a welded joint with a suitable size nugget and a correspondingly larger range of welding current and better joint performance can be obtained. Background technique [0002] The development and application of hot-formed steel (press hardened steel, PHS) is one of the most important lightweight materials to realize automobile lightweight and improve automobile safety. It is widely used in the production of front / rear bumpers, B-pillars, A / B / C pillars and sill reinforcement plates, center tunnels, door anti-collision beams, roof side beams and other important structural parts, such as PHS1500, PHS1800 and PHS2000 with a tensile strength higher than 1500MPa. However, the charac...

Claims

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Application Information

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IPC IPC(8): B23K11/11B23K11/34B23K11/36
CPCB23K11/11B23K11/34B23K11/36
Inventor 张国涛杨上陆黄健陶武王亚芬李科龙
Owner SHANGHAI INST OF OPTICS & FINE MECHANICS CHINESE ACAD OF SCI
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