Room and Elevated Temperature Compressive Deformation Behavior of AISI 316L Alloy Fabricated by Selective Laser Melting Process

초록

This study investigated the microstructure and compressive properties (at room & high temperatures) of Fe-Cr-Ni based AISI 316L alloy, manufactured by selective laser melting process. The effect of stress relieving heat treatment on the microstructure and mechanical properties also examined. Regardless of the stress relieving heat treatment, the SLMed AISI 316L alloy exhibited typical molten pools and fine columnar structures which grew along the laser heat source. A cellular type dendrite structure was also observed inside the molten pool. After heat treatment, the low angle boundary fraction decreased and the high angle boundary fraction increased in the SLMed AISI 316L alloy. In the 25 degrees C, 500 degrees C, 700 degrees C, 900 degrees C compressive results, the heat treated 316L alloy showed lower yield strengths than the as fabricated alloy at all temperature conditions. However, the difference in yield strength between the as fabricated and heat treated alloys gradually decreased with increasing temperature. Surface and cross-sectional fractographies showed that the heat treated alloy accommodated more plastic deformation. This was considered the cause of the more pronounced work hardening of the heat treated alloy, as identified in the stress versus strain curves. The correlations between microstructure, temperature dependent mechanical properties and stress relieving heat treatment were also discussed based on these findings.

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