Double Pulse Resistance Spot Welding of Dual Phase Steel: Parametric Study on Microstructure, Failure Mode and Low Dynamic Tensile Shear Properties

Abstract

Resistance spot welding (RSW) of dual phase (DP) steels is a challenging task due to formation of brittle martensitic structure in the fusion zone (FZ), resulting in a low energy capacity of the joint during high-rate loading. In the present study, in situ postweld heat treatment (PWHT) was carried out by employing a double pulse welding scheme with the aim of improving the mechanical performance of DP590 steel resistance spot weld joint. Taguchi method was used to optimize in situ PWHT parameters to obtain maximum peak load and failure energy. Experiments were designed based on orthogonal array (OA) L16. Mechanical performance was evaluated in terms of peak load and failure energy after performing low dynamic tensile shear (TS) test. Microstructural characterization was carried out using a scanning electron microscope (SEM). The results show that improvements of 17 and 86% in peak load and failure energy, respectively, were achieved in double-pulse welding (DPW) at optimum conditions compared to traditional single-pulse welding (SPW). The improvement in mechanical performance resulted from (i) enlargement of the FZ and (ii) improved weld toughness due to tempering of martensite in the FZ and subcritical heat affected zone (SCHAZ). These factors are influenced by heat input, which in turn depends upon in situ PWHT parameters.

Projeksi̇yon Kaynağin Proses Parametreleri̇ni̇n S355mc Klevi̇s Braketi̇n Bağlanti Performansina Etki̇si̇

“…Ayrıca, elde edilen sonuçların istatistiksel güvenilirliği incelenir. Bu amaçla öncelikle, Denklem 2'ye göre sinyal/gürültü (S/N) oranının genel değişkenliğini temsil eden SST değeri (toplam kareler toplamı) hesaplanır (Soomro, 2021).…”

Correlation Tests of Ultrasonic Wave and Mechanical Parameters of Spot-Welded Joints

“…Kishore et al [ 10 ] compared the processes of welding for steel with and without a zinc coating and found that during the welding process, the coating on the surface of the steel reduces the diameter of the weld nugget. Soomro et al [ 11 ] proposed the use of double pulse resistance spot welding as a postweld heat treatment method that improves the mechanical properties of the spot weld. On the basis of the research, it was found that for galvanized dual phase (DP590) steel, the most important parameter influencing the mechanical performance of the spot weld is the welding current, then the welding time and the cooling time (for double pulse resistance spot welding).…”

Paslanmaz Çeliklerin Farklı Akımlarda MİG Kaynak Yöntemiyle Birleştirilmesinin İncelenmesi

“…Pulse, elektron ışını malzemelerin mikroyapısıyla faz kompozisyonunu değiştirerek alan niteliklerini ilerletmesini sağlayan kaynaktır [16]. Bu teknoloji, saf tabaka oluşumuna nedendir [17].…”