Study of Solidification Cracking Susceptibility during Laser Welding in an Advanced High Strength Automotive Steel

Gautam Agarwal,Murugaiyan Amirthalingam,Marcel Hermans,He Gao

doi:10.3390/met8090673

Gautam Agarwal, Murugaiyan Amirthalingam + Show 2 more

Open Access

https://doi.org/10.3390/met8090673

Copy DOI

Abstract

Susceptibility to weld solidification cracking in transformation-induced plasticity steel sheets was studied using a modified standard hot cracking test used in the automotive industry. To vary the amount of self-restraint, bead-on-plate laser welding was carried out on a single-sided clamped specimen at increasing distances from the free edge. Solidification cracking was observed when welding was carried out close to the free edge. With increasing amount of restraint, the crack length showed a decreasing trend, and at a certain distance, no cracking was observed. With the aid of a finite element-based model, dynamic thermal and mechanical conditions that prevail along the transverse direction of the mushy zone are used to explain the cracking susceptibility obtained experimentally. The results indicate that the transverse strain close to the fusion boundary can be used as a criterion to predict the cracking behavior. The outcome of the study shows that optimum processing parameters can be used to weld steels closer to the free edge without solidification cracking.

Highlights

Solidification cracking, known as hot tearing in casting, is one of the prominent defects in welding, casting and/or additive manufacturing
P1 is at a distance of 3 mm, while P2 and P3 are at 2.5 mm and 4 mm
With the use of the presented hot cracking test, in general, any given material is most susceptible to solidification cracking when welding is carried out close to the free edge

Summary

Introduction

Solidification cracking, known as hot tearing in casting, is one of the prominent defects in welding, casting and/or additive manufacturing. Mitigating the occurrence of solidification cracking is important to achieve good weldability. For more than five decades, solidification cracking in welding/casting of various alloys has been studied extensively [1,2,3,4]. Increasing environmental concern has motivated the automotive industry to develop thinner gauge steels with high strength, ductility and toughness. The use of lightweight steel in the automotive body reduces the average fuel consumption.

Methods

Results

Discussion

Conclusion