Effect of Ti on mechanical performance and dimensional stability of MIM HK30 stainless steel

Various contents of Ti(mass fraction of 0,0.4%,0.8% and 1.2%) were added respectively into gas-atomized HK30 stainless steels powder,and the HK30 stainless steel preforms fabricated by MIM(Metal Injection Molding) were sintered at 1 270 ℃,1 290 ℃ and 1 310 ℃,respectively.The effect of Ti content on the mechanical properties and dimensional stability of HK30 stainless steels was investigated.The density,tensile strength,elongation and dimensional stability of HK30 stainless steels with adding different contents of Ti were tested.The results show that the density,tensile strength and elongation decrease with increasing Ti content.Since Ti is priority to Fe in combining with C,it reduce the content of C that combined with Fe,and then it improve the temperature of liquid formation,and then reduce the liquid quantity in high temperature sintering and lower the densification rate,which results in the improvement of dimensional stability and avoiding over-sintering.The optimum sintering technology for HK30 is 1 290 ℃/6 h+0.4%Ti,by this technology the over-sintering can be avoided and dimensional stability can be improved though tensile strength at 800 ℃ slightly decreasing.The samples have the best comprehensive properties with relative density of 95.7%,room temperature tensile strength of 535 MPa,tensile strength of 215 MPa at 800 ℃ and room temperature elongation of 21.7%.