Effect of Heat Treatment on the Microstructure,Mechanical Properties and Corrosion Resistance of Selective Laser Melted 304L Stainless Steel

摘要

The influence of heat treatment holding temperatures from 600 to 1300℃ on the microstructure,mechanical properties and corrosion resistance in selective laser melted(SLMed)304L stainless steel is investigated in this work.The results reveal that there is no remarkable microstructure change after holding at 600℃ for 2 h,while recrystallization leads to a slight decrease in grain size in the temperature range of 700–900℃.The heat treatment at temperatures from 1000 to 1300℃ for 2 h obviously affects the morphology of grains in SLMed 304L stainless steel.Combining effects of grain coarsening,delta-ferrite(δ)phases reduction and residual stress release during heat treatment lead to the reduction of yield strength and an increasing elongation.The elongation of the samples heat treated at 800℃ for 2 h is,however,significantly decreased due to the increase in the amount of sigma(σ)phase.A remarkable increase in the amount ofδferrite results in an increase in yield strength but a decrease in ductility after heat treatment at 1300℃ for 2 h.The corrosion resistance of the samples heat treated at 1300℃ is significantly improved due to the substantial reduction of brittle phase(σ).There is no obvious effect of the presence ofδferrite on corrosion behavior.