Zinc-coated steel sheet with high resistance spot weldability

• Main Authors: PANAHI DAMON, CHALLA VENKATASURYA PAVAN, GIRINA OLGA, BENLATRECHE YACINE, CHAKRABORTY ANIRBAN, GHASSEMI-ARMAKI HASSAN, CREMEL SEBASTIEN, PIPARD JEAN-MARC
• Format: Patent
• Language: Chinese; English
• Published: 17.03.2020
• Subjects: ALLOYS; CHEMICAL SURFACE TREATMENT; CHEMISTRY; CLADDING OR PLATING BY SOLDERING OR WELDING; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATIONOR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY IONIMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; COATING MATERIAL WITH METALLIC MATERIAL; COATING METALLIC MATERIAL; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; DIFFUSION TREATMENT OF METALLIC MATERIAL; FERROUS OR NON-FERROUS ALLOYS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION INGENERAL; MACHINE TOOLS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; METAL-WORKING NOT OTHERWISE PROVIDED FOR; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; PERFORMING OPERATIONS; SOLDERING OR UNSOLDERING; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THESURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; TRANSPORTING; TREATMENT OF ALLOYS OR NON-FERROUS METALS; WELDING; WORKING BY LASER BEAM

A method for producing a zinc or zinc-alloy coated steel sheet with a tensile strength higher than 900 MPa, for the fabrication of resistance spot welds containing in average not more than two LiquidMetal Embrittlement cracks per weld having a depth of 100[mu]m or more, comprising the successive steps of providing a cold-rolled steel sheet, the nominal composition of which contains, in weight percent: 0.07% <= C <= 0.5%, 0.3% <= Mn <= 5%, 0.010% <= Al <=1%, 0.010% <= Si <= 2.45%, with 0.35% <= (Si+Al) <= 2.5%, 0.001% <= Cr <= 1.0%, 0.001% <= Mo <= 0.5%, and optionally, 0.005% <= Nb <=0.1%, 0.005% <= V <= 0.2%, 0.005% <= Ti <= 0.1%, 0.0001% <= B <= 0.004%, 0.001% <= Cu <= 0.5%, 0.001% <= Ni <= 1.0%, the remainder being iron and unavoidable impurities from the smelting, in contents such asS<0.003%, P<0.02%, N<0.008%, heating cold-rolled steel sheet up to a temperature T1 comprised between 550 degrees centigrade and Ac1+50 degrees centigrade in a furnace zone with an atmosphere (A1) containing from 2 to 15% hydr