The Effect of Selected Spot Resistance Welding Parameters on Properties of Martensite-Structured AHSS

Abstract

: The paper presents the effect of welding current and clamping force on the properties of spot resistance-welded joints made of 1.8 mm thick steel DOCOL 1200M. Because of the fact that martensite-structured steel DOCOL 1200M is hardened when exposed to deforming force, it is used to make energy absorbers or car header panels. Test joints, made using a robotic welding station, were subjected to macro and microscopic metallographic tests, hardness measurements and strength tests. The obtained test joints were subjected to strength verification performed in accordance with PN-EN ISO 14273:2016. The tests demonstrat-ed that excessively high clamping force combined with relatively low welding current do not guarantee the obtainment of a joint characterised by required strength. However, by increasing welding current and reducing clamping force it is possible to increase the strength of welded joints. The use of appropriate spot resistance welding parameters enables the making of joints in steel DOCOL 1200M steel characterised by a satisfactory level of strength