粉末注射成形无镍高氮不锈钢工艺

Powder injection molding of nickel-free high nitrogen stainless steel

采用粉末注射成形工艺制备了无镍高氮奥氏体不锈钢(0Cr17Mn11Mo3N),研究了喂料的流变行为,注射工艺及烧结工艺。结果表明:64 vol%气雾化0Cr17Mn11Mo3粉末与适量的粘结剂(65 wt%石蜡+30 wt%高密度聚乙烯+5 wt%硬脂酸)混合后的喂料具有较好的流变性能;最佳注射工艺参数为注射压力75～95 MPa,相应的注射温度为160～170℃;提高烧结温度有利于提高烧结体的密度,但是对提高氮含量不利,而增加烧结氮气氛压力可以获得较高的氮含量,但是不利于提高烧结体密度,最佳的烧结工艺为0.1 MPa氮气压力下1300℃烧结2 h,此时烧结体相对密度可以达到99%,氮含量可达到0.78%。

Nickel-free high nitrogen austenitic stainless steel（0Cr17Mn11Mo3N） was prepared by powder injection molding.The rheological behavior of feedstock,injection and sintering processes for fabricating the steel were investigated.The results show that the feedstock which consists of 64 vol% gas-atomized 0Cr17Mn11Mo3 powder and some binder containing 65 wt% paraffin wax（PW）,30 wt% high density polyethylene（HDPE） and 25 wt% aric acid（SA） exhibits good rheological properties.The best injection conditions are injection pressure of 75-95 MPa and injection temperature of 160-170 ℃.The density of the sintered specimens increases with the increase of sintering temperature,but the content of nitrogen decreases.Additionally,the increase of sintering nitrogen pressure benefits the increase of nitrogen content of sintered specimens,but is detrimental to gaining higher sintering density.The optimized sintering conditions are sintering temperature of 1300 ℃,sintering time of 2 h with 0.1 MPa nitrogen pressure,at which the sintered part with relative density of 99% and nitrogen content of 0.78 wt% is obtained.