Substantial electrode life enhancement in resistance spot welding of galvanised steels through nanolayered multi-layer CrN/(Cr,Al)N coating

Abstract

The short electrode life is one of the most important problems associated with resistance spot welding of galvanised steel sheets. In this study, a nanolayered multi-layer CrN/(Cr,Al)N coating was deposited on the tip of the electrode by applying the cathodic arc physical vapour deposition process with the layer thickness of about 30 nm and an overall thickness of 1.1 µm. The electrode life test confirmed that the coating could extend the electrode life up to 125%. The coated electrode showed a significantly lower growth rate (∼0.3 µm per weld), in comparison to the un-coated one (∼1 µm per weld). The degradation of the electrode could be subdivided into two subsequent steps: the degradation of the electrode periphery and the degradation of the electrode tip. The CrN/(Cr,Al)N coating could effectively protect the electrode tip periphery from zinc adhesion and postpone the first stage electrode degradation which delayed the second one.

Life and failure of oriented carbon nanotubes composite electrode for resistance spot welding

“…In addition, due to the low deposition rate of ESD, and manual operation makes the composite coating thickness less stable, which limits its application in large-scale industrial production. MALMIR et al [2] used the cathodic arc Physical Vapor Deposition (PVD) process to deposit a nano-multilayer CrN/(Cr,Al)N coating on the electrode surface, which enhanced the wettability, resistance to oxidation and thermal shock of the electrode tips, thereby slowing down the electrode failure rate. However, the coating is easy to fall off, and it also deteriorated the electrical and thermal conductivity of the electrodes.…”

“…Therefore, this method has limited improvement in electrode life. (2) Design the special structure of the electrode tip. CHEN et al [3] designed the electrode end face as a central micro-concave, which effectively improved the connection strength of RSW joints.…”

Correlating Electrode Degradation with Weldability of Galvanized BH 220 Steel during Electrode Failure Process of Resistance Spot Welding

“…However, electrode life plays a significant role in assembling car bodies using the RSW technique. The electrode life is short and needs to be trimmed and updated, resulting in slower production efficiency and higher production costs [19]. However, most of the previous work on BH steel has only addressed welded joint properties such as tensile strength, microhardness, weld geometry, and microstructure.…”