A New Test Method for Evaluation of Solidification Cracking Susceptibility of Stainless Steel during Laser Welding

Abstract

A new test method named “Trapezoidal hot” cracking test was developed to evaluate solidification cracking susceptibility of stainless steel during laser welding. The new test method was used to obtain the solidification cracking directly, and the solidification cracking susceptibility could be evaluated by the solidification cracking rate, defined as the ratio of the solidification cracking length to the weld bead length under certain conditions. The results show that with the increase in the solidification cracking rate, the solidification cracking susceptibility of SUS310 stainless steel was much higher than that of SUS316 and SUS304 stainless steels during laser welding (at a welding speed of 1.0 m/min) because a fully austenite structure appeared in the weld joint of the former steel, while the others were ferrite and austenitic mixed structures during solidification. Besides, with an increase in welding speed from 1.0 to 2.0 m/min during laser welding, the solidification cracking susceptibility of SUS310 stainless steel decreased slightly; however, there was a tendency towards an increase in the solidification cracking susceptibility of SUS304 stainless steel due to the decrease in the amount of ferrite under a higher cooling rate.

Hot‐cracking susceptibility of fully austenitic stainless steel using pulsed‐current gas tungsten arc‐welding process

“…The choice of the fan‐shaped specimen test was based on its simplicity, reproducibility, and effectiveness (cracking sensitivity). In addition, it does not require special equipment since it is a self‐restraint specimen, in addition to the variable degree of restraint along the axis of the specimen 3,11 . In this report, a complete interpretation of the obtained results is provided based on the macrostructure and microstructure of the weld bead and crack morphology, 6 from which the effect of the bead structure on the cracking susceptibility is elucidated.…”

Solidification cracking susceptibility associated with a teardrop-shaped weld pool

“…This is the same ranking reported by Soysal and Kou in both gas-metal arc welding using matching filler metals [20] and in autogenous GTAW [7], and by Kou [3] in predicting the crack susceptibility based on | dT / d ( f S ) 1/2 | near the roots as the index. Matsuda and Nakata [19] welded stainless steels by electron-beam welding and Wang et al [21] by laser-beam welding. They both reported the crack-susceptibility ranking of Grade 310 > Grade 316 > Grade 304.…”

A review: Suppression of the solidification cracks in the laser welding process by controlling the grain structure and chemical compositions

“…The velocity is the factor affecting the temperature gradient and solidification and requires more investigation (Nguyen et al, 2020). Wang et al (2020) studied the effect of velocity on the solidification crack of three types of stainless steel with different grain structures. At 1.0 m/min velocity, SUS310 has more crack susceptibility because of the full austenite structure, while SUS304 appears with more ferrite structure and could have less solidification crack susceptibility.…”