ArcelorMittal S.A.
Resistance Spot Welding Method for Joining Zinc Coated Steel Sheets

Abstract:

A method for resistance spot welding comprising the following successive steps: --providing at least two steel sheets with thickness (th) comprised between 0.5 and 3 mm, at least one of the sheets being a zinc or zinc-alloy coated steel sheet (A) with a tensile strength (TS) higher than 800 MPa and a total elongation (TEL) such as (TS).times.(TEL)>14000 MPa %, wherein the composition of the steel substrate of (A) contains, in weight: 0.05%.ltoreq.C.ltoreq.0.4%, 0.3%.ltoreq.Mn.ltoreq.8%, 0.010%.ltoreq.Al.ltoreq.3%, 0.010%.ltoreq.Si.ltoreq.2.09%, with 0.5%.ltoreq.(Si+Al).ltoreq.3.5%, 0.001%.ltoreq.Cr.ltoreq.1.0%, 0.001%.ltoreq.Mo.ltoreq.0.5% and optionally: 0.005%.ltoreq.Nb.ltoreq.0.1%, 0.005%.ltoreq.V.ltoreq.0.2%, 0.005%.ltoreq.Ti.ltoreq.0.1%, 0.0003%.ltoreq.B.ltoreq.0.005%, 0.001%.ltoreq.Ni.ltoreq.1.0%, the remainder being Fe and unavoidable impurities, --performing resistance spot welding of the at least two steel sheets for producing a weld with an indentation depth (IDepth) on the surface of said steel sheet (A) such as: 100 .mu.m.ltoreq.(IDepth).ltoreq.18.68 (Zn.sub.sol)-55.1, wherein (IDepth) is in micrometers and wherein Zn.sub.sol is the solubility of Zn in the steel of sheet (A) at 750.degree. C., in weight %.