N/H气氛下烧结温度对430L不锈钢块体的性能影响

Effect of sintering temperature on properties of 430L stainless steel block in N/H atmosphere

为系统研究N/H气氛下不同烧结温度对430不锈钢粉末冶金件微观结构、密度、力学性能的影响规律和作用机理,用模压成型-脱脂-气氛烧结工艺,在1100~1330℃烧结不锈钢粉末。结果表明:随温度升高,块体致密度显著提升,但晶粒粗化严重,导致性能衰减。1290℃时制备的不锈钢块的综合性能优异,抗拉强度为454 MPa,伸长率为7%,冲击功为58 J/cm^(2)。在N_(2)-H_(2)气氛下高温烧结块体表层生成了梯度分布的Cr_(2)N相,不锈钢硬度高达100.5HRB。这是因为基体组织均匀、具有梯度结构的Cr_(2)N富集层及弥散分布的平均粒径为2.27μm的Si颗粒钉扎效应协同作用的结果。该工艺流程短、能耗低,无需后续处理即可制备出满足要求的粉末冶金件。

In order to systematically study the effect of sintering temperature on microstructure,density and mechanical properties of 430 stainless steel powder metallurgy parts under N/H atmosphere,the stainless steel powder was sintered at 1100⁃1330℃by die⁃die⁃degrease⁃atmosphere sintering process.The results show that the bulk density increases significantly with the increase of temperature,but the grain coarsening is serious,which leads to the degradation of properties.The stainless steel block prepared at 1290℃has excellent comprehensive properties,the tensile strength is 454 MPa,the elongation is 7%,and the impact work is 58 J/cm^(2).Cr_(2)N phase with gradient distribution is formed on the surface of sintered block in N_(2)⁃H_(2) atmosphere,and the hardness of stainless steel is as high as 100.5HRB.This is due to the synergistic effect of the uniform matrix structure of Cr_(2)N enriched layer with gradient structure and the dispersion of Si particles with an average particle size of 2.27μm.This process has short flow and low energy consumption,and can produce powder metallurgy parts that meet the requirements without subsequent treatment.