316L不锈钢粉末高速压制行为

采用自行设计制造的18m高落锤式高速压机,研究316L不锈钢粉末的高速压制行为.实验结果表明,冲击速度增大可有效提高生坯密度,对室温粉末进行高速压制,当冲击速度从10 m/s提高到18m/s时,生坯密度从7.18 g/cm3提高到7.61 g/cm3.而在同样冲击速度下,对160℃温粉末进行高速压制时,生坯密度从7.33 g/cm3提高到7.76 g/cm3.同时生坯强度随冲击速度的提高而升高,冲击速度从10 m/s提高到18m/s时,160℃压制的生坯强度从72.5 MPa提高到94.1 MPa,室温压制生坯强度从62.1MPa提高到89.3MPa.通过对生坯SEM照片的分析,得知高速压制过程中粉末会发生严重的塑性变形和碎裂现象,孔隙的形状也会发生改变.该文还对高速压制致密化机理进行了探讨,指出在较高的速度压制时,颗粒间的摩擦和绝热剪切作用使粉末颗粒界面的温度升高,有利于粉末颗粒的塑性变形和焊合,从而有效提高了生坯的密度.

Behaviors of 316L stainless steel powders in high velocity compaction

Behaviors of 316L stainless steel powders in the process of high velocity compaction(HVC) were studied.The results show that increasing impact velocity can improve compact density effectively.When impact velocity increases from 10m/s to 18 m/s,the compact density increases from 7.18 g/cm3 to 7.61 g/cm3 at room temperature,and when impact at 160 ℃,with the same velocity,compact density increases from 7.33 g/cm3 to 7.76 g/cm3.At the same time,the compact strength increases greatly with increasing impact velocity,when impact velocity increases from 10 m/s to 18 m/s the strength of samples compacted at 160 ℃ increases from 72.5 MPa to 94.1 MPa,the strength of samples compacted at room temperature increases from 62.1 MPa to 89.3 MPa.Through the analysis of SEM photographs,powders’ plastic deformation and fragmentation phenomenon can be found,and the pores’ shape changes.Then the densification mechanism of HVC is discussed.In high velocity compaction,the friction between particles and adiabatic shearing action make the temperature of particles’ interface increase,which are beneficial to the powders’ plastic deformation and welding,thus the density of compacts increases effectively.