In the pursuit for light-weighting, the application of high strength steels for the fabrication of structural automotive parts is on the rise. There are multiple strengthening mechanisms to enhance the strength of steels.

The strength depends on metallurgical features and processing route of the steels. The welding is a thermal intensive fabrication process and the heat cycles during a welding process, significantly alter the base material properties in the Heat Affected Zone (HAZ).

In the welding of high strength steels, the HAZ can soften and local reduction of mechanical properties in HAZ can make the HAZ area prone to failures. This is further amplified with localized strain concentration in softened zones.

In the current study, detailed investigations were undertaken to investigate on the mechanism of HAZ softening in welded joint, made of high strength steel grade. The effects of weld heat input and preheating of base material were also investigated.

Metallurgical investigations were undertaken to understand the evolution of metallurgical phases, responsible for HAZ softening. The static mechanical properties of welded joints were also evaluated.

The attempt was made to establish a relationship between weld heat inputs, HAZ microstructure and hardness and mechanical properties of welded joint.

This article is shared by Shiv Chauhan, V Senthilkumaran, Deodatta Shende, Hemant More, Ravi Dhadange and Mahendra Kumar.