Cold-rolling effects on the microstructure properties of 316L stainless steel parts produced by Laser Powder Bed Fusion (LPBF)

Abstract

Laser Powder Bed Fusion (LPBF) technology provides new opportunities to enhance some piece-producing processes in the industry. Moreover, LPBF microstructures can heavily differ from microstructures usually obtained through traditional processes, especially 316L LPBF ones which combine both strength and ductility at room temperature. However, 316L LPBF microstructure evolution upon cold-rolling has not yet been extensively studied. In the present study, the effect of cold-rolling was investigated on the distinct 316L as-built microstructures showing different characteristics regarding mean grain size and texture. At first, LPBF 316L has sufficient ductility to be cold-rolled without any intermediate heat-treatments. Differences between initial microstructures affect the extent of grain refinement and texture decay. Indeed, the mean grain size and texture remain stable until 20% thickness reduction for one of the studied microstructure while they strongly decrease for the other one. Both microstructures show mechanical twinning after being cold-rolled with a twinned surface ratio exceeding 30%. Mechanical twins can also cross molten pool boundaries.

Keywords

• Additive manufacturing
• Cold-rolling
• LPBF
• SLM
• 316L
• Twinning