阅读说明：本技术 至少两个金属基底的组件 (Assembly of at least two metal substrates ) 是由 蒂亚戈·马卡多阿莫里姆 斯特凡妮·米绍 马克西姆·布罗萨尔 帕斯卡尔·贝尔托 让-马里·埃尔 于 2019-09-09 设计创作，主要内容包括：本发明涉及用于制造通过至少一个点焊接头点焊在一起的至少两个金属基底的组件的方法、能够根据该方法获得的组件以及该组件的用于制造机动车辆的用途,该方法包括两个步骤。(The invention relates to a method for manufacturing an assembly of at least two metal substrates spot-welded together by means of at least one spot weld joint, the assembly obtainable according to the method and the use of the assembly for manufacturing a motor vehicle, the method comprising two steps.)

1. A welding method for manufacturing an assembly, the welding method comprising the steps of:

A. providing at least two metal substrates (3, 3'), wherein the first metal substrate (3) is a hardened steel part coated with the following layers:

■ alloy coating (4), the alloy coating (4) comprising zinc, silicon, optionally magnesium, and balance aluminium, the alloy coating (4) being directly covered with

■ a natural oxide layer comprising ZnO and optionally MgO,

B. applying a spot welding cycle using a spot welder comprising a welding electrode (1, 1') and a spot welding power supply (2), said spot welding power supply (2) applying an inverted direct current through said at least two metal substrates of step a), said spot welding cycle (21, 31, 41, 51) comprising the sub-steps of:

i. having one pulse (22, 32, 42, 52) of a pulsating current (Cp) applied through the at least two metal substrates joined together using a welding electrode connected to the spot welding power supply, and immediately thereafter,

a welding step (23, 33, 43, 53) with a welding current (Cw) applied through the at least two metal substrates, and

wherein the current Cp is higher than the current Cw and the duration of the pulsation is shorter than the duration of the welding.

2. Welding method according to claim 1, wherein in step B.i) the pulsating current (Cp) is between 8.0kA and 30.0 kA.

3. Welding method according to claim 1 or 2, wherein in step B.i) the pulse duration is 5-60 milliseconds.

4. Welding method according to any one of claims 1-3, wherein in step B.ii) the welding current (Cw) is between 0.1kA and 15 kA.

5. Welding method according to any one of claims 1-4, wherein in step B.ii) the welding duration is 150-500 milliseconds.

6. The welding method according to any one of claims 1 to 5, wherein the welding force during the spot welding cycle is between 50 and 550 daN.

7. The welding method of claim 6, wherein the welding force during the spot welding cycle is between 350 and 550 daN.

8. The welding method of claim 6, wherein the welding force during the spot welding cycle is between 50 and 350 daN.

9. The welding method according to any one of claims 1 to 8, wherein the welding frequency is between 500Hz and 5000 Hz.

10. The welding method according to any one of claims 1 to 9, wherein the welding step b.ii) comprises a plurality of pulses, at least one pulse B.i directly following a first pulse of the welding step.

11. Welding method according to any one of claims 1 to 10, wherein the spot welding cycle shape (21, 31, 41, 51) is selected from:

● includes rectangular forms of rectangular pulsing peaks (22) and rectangular welding peaks (23),

● includes parabolic forms of parabolic pulsating peaks (32) and parabolic welding peaks (33),

● includes triangular forms of triangular shaped pulsating peaks (42) and triangular shaped welding peaks (43),

● include parabolic and rectangular forms of parabolic pulsating peaks and rectangular welding peaks, an

● include triangular and rectangular forms of triangular pulsing peaks and rectangular welding peaks.

12. An assembly of at least two metal substrates (3, 3') spot-welded together by at least one spot weld joint, obtainable according to claims 1 to 11, the assembly comprising:

-a first metal substrate (3), the first metal substrate (3) being a hardened steel part coated with:

■ alloy coating (4), the alloy coating (4) comprising zinc, silicon, optionally magnesium, and balance aluminium, the alloy coating (4) being directly covered with

■ a natural oxide layer comprising ZnO and optionally MgO,

-the spot weld joint comprises a nugget (5); and the spot weld joint is configured such that at least a portion of the native oxide layer and/or the alloy coating is absent on a top portion (6) of the spot weld joint.

13. The assembly of claim 12, wherein the alloy coating of the hardened steel component comprises 0.1 to 40.0 wt.% zinc.

14. The assembly of claim 13, wherein the alloy coating of the hardened steel component comprises 0.1 to 20.0 wt.% zinc.

15. The assembly of any of claims 12 to 14, wherein the alloy coating of the hardened steel component comprises 0.1 to 20.0 wt.% silicon.

16. The assembly of claim 15, wherein the alloy coating of the hardened steel component comprises 0.1-15.0 wt.% silicon.

17. The assembly of any of claims 12 to 16, wherein the alloy coating of the hardened steel component comprises 0.1 to 20.0 wt.% magnesium.

18. The assembly of claim 17, wherein the alloy coating of the hardened steel component comprises 0.1 to 10.0 wt.% magnesium.

19. Assembly according to any one of claims 12 to 18, wherein the second metal substrate (3') is a steel substrate or an aluminum substrate.

20. An assembly according to claim 18, wherein the second steel substrate is a hardened steel component according to any one of claims 12 to 18.

21. The assembly of any one of claims 12 to 20, comprising a third metal substrate, the third metal substrate being a steel substrate or an aluminum substrate.

22. Use of the assembly according to any one of claims 12 to 21 or obtainable according to the method of any one of claims 1 to 11 for the manufacture of a motor vehicle.

Examples

All tests were hot dip coated with a coating comprising 3 wt.% silicon, 2 wt.% magnesium, 10 to 12 wt.% zinc, the balance being aluminium1500 steel plate. The steel sheet was then press hardened at an austenitizing temperature of 900 ℃ for 5 minutes.

Then, for each test, two identical press hardened parts were welded together.

The weld range is determined according to specification SEP 1220-2. The weld test started at 3kA and increased by 0.2kA per two spot welds. The spattering limit is obtained when two consecutive spatters occur at the same current level. When the spatter limit was reached, the welding current was reduced in 0.1kA steps to have three consecutive weld samples without spattering at the same current level. This current level is defined as the upper welding limit of the current range: imax.

Thereafter, the lower limit Imin is obtained. The Imin search was done by using a standard of 4 √ t, where t is the plate thickness. This standard defines a minimum acceptable diameter value that ensures weld quality and strength. For confirmation, five consecutive welded samples having a weld diameter more excellent than the minimum weld diameter were obtained.

For trials 1 to 12, 17 and 18, the welding cycle optionally included a welding step with a pulsation with pulsating current Cp and with a welding current Cw defined by Imin and Imax according to specification SEP 1220-2. For trials 13 to 16, the welding cycle comprised one pulse with a pulsating current Cp and three or four welding steps with a welding current Cw defined by Imin and Imax according to specification SEP1220-2, with a temporary stop being performed between each welding step.

The frequency is 1000 Hz. The obtained Imin, Imax and welding current ranges are in table 1 below.

*: according to the invention

Tests 1, 2, 3, 9, 10 and 16 are not weldable, i.e. do not meet the criteria Imin and Imax defined in specification SEP 1220-2. The welding range of the test according to the invention is equal to or greater than 1 kA.

Example 2: heterogeneous welding test

A Usibor 1500 steel sheet was hot dip coated with a coating comprising 3 wt% silicon, 2 wt% magnesium, 12 wt% zinc, and the balance aluminum. The steel sheet was then press hardened at an austenitizing temperature of 900 ℃ for 5 minutes. The steel sheets were welded together with DP600 steel grade (C: 0.14 wt%, Mn: 2.1 wt% and Si: 0.4 wt%) coated with a zinc coating. The welding range was determined as in example 1. The frequency is 1000 Hz. The obtained Imin, Imax and welding current ranges are in table 2 below.

*: according to the invention

The welding range of the test according to the invention is equal to or greater than 1 kA.

Example 3: electrode life testing

Electrode life is defined as the final number of welds of the test strip before reaching more than two of the eight welds below the defined minimum weld diameter. The minimum weld diameter was 4.7 mm.

Two coated hardened steel parts prepared according to test 4 were welded together using a welding method according to the invention comprising one pulsation and welding step. During 10 milliseconds, the ripple current was 10 kA. The welding current determined for test 4 in example 1 was Imax. A plurality of spot welds are performed on the two coated hardened parts using electrodes, and the weld diameter is measured for each spot weld. The results are in table 3 below.

*: according to the invention

According to the invention, the weld diameter is always higher than the minimum weld diameter for test 4.