Room temperature and high temperature micro-forming analysis of SS304 foil

The micro-sheet metal forming (MSMF) processes such as microstamping and micro-deep drawing can be used to mass-produce miniature parts. However, to design the tools and the processes, material behavior of workpiece under various deformation conditions is required. This paper analyzes the material behavior of 200-mu m thickness Stainless steel-304 foil with room-temperature tensile (RTT) tests and high-temperature tensile (HTT) tests. The effect of strain rate and temperature on flow stress behavior, surface roughness, microstructural evolution and fracture mechanism have been examined. It is observed that the percentage elongation for HTT tests is significantly higher than as compared to RTT tests. However, the percentage elongation and the tensile strength during HTT tests are dependent on the strain rate and decreases with a decrease in the strain rate. Recrystallization followed by grain growth in the material took place during high-temperature deformation, thereby changing the surface roughness and fracture mechanism. All the RTT specimens showed ductile failure with characteristic trans-granular dimpled fracture surfaces. The HTT specimens, in contrast, have intergranular fracture by grain pull out due to crack propagation along the grain boundaries. The present analysis can be used to guide the designing of micro-sheet metal forming processes to obtain the required micro-parts.

Automated summary

This paper analyzes the material behavior of stainless steel-304 foil with different tests and examines the effects of strain rate and temperature on flow stress behavior, surface roughness, microstructural evolution, and fracture mechanism. The study finds that the percentage elongation and tensile strength during high-temperature tests are dependent on strain rate and decrease with a decrease in strain rate. Recrystallization and grain growth occur during high-temperature deformation, leading to changes in surface roughness and fracture mechanism. The analysis can guide the design of micro-sheet metal forming processes.