C-xFe₂O₃对粉末冶金Fe-18Mn-3Cu-C高锰无磁钢微观组织和力学性能的影响

Effect of C-xFe₂O₃ on Microstructure and Mechanical Properties of Powder Metallurgy Fe-18Mn-3Cu-C High Manganese Non-Magnetic Steel

摘要: 为了研究C-xFe₂O₃对粉末冶金高锰无磁钢微观组织和力学性能的影响，将高锰预合金粉、电解Cu粉与一定量的C-Fe₂O₃混合，随后在烧结气氛为分解氨(N₂:H₂ = 1:3)的网带炉中进行梯度工艺烧结，最终制得Fe-18Mn-3Cu-C块体合金。后对烧结体进行显微组织表征和力学性能测试。结果表明：烧结合金的组织均由奥氏体基体，铜相，富锰相组成，随着Fe₂O₃含量的增加(0~0.8 wt%)，高锰无磁钢的致密度、抗拉强度和总伸长率均呈现先升高后降低的趋势，在Fe₂O₃的质量分数为0.4%时，其致密度达到了最高值92.67%，对应的抗拉强度与总伸长率分别为581 MPa和8.1%，经计算可知，0.4wt% Fe₂O₃的加入将高锰无磁钢的抗拉强度和总伸长率分别提高了9.4%和66.7%，强韧化效果显著。这说明在烧结过程中Fe₂O₃粉与游离态石墨C和分解氨中的H₂发生了还原反应，通过活化作用加速了合金粉末的烧结过程，并且促进了Mn元素的均匀化，同时促进了孔隙的闭合，提高了合金的致密度。

Abstract: In order to study the effect of C-xFe₂O₃ on the microstructure and mechanical properties of powder metallurgy high manganese non-magnetic steel, the high manganese pre-alloyed powder, electrolytic copper powder and a certain amount of C-Fe₂O₃ were mixed, and then gradient process sintering was carried out in a mesh furnace with sintering atmosphere of decomposition ammonia (N₂:H₂ = 1:3). Finally, Fe-18Mn-3Cu-C bulk alloy was prepared. The microstructure and mechanical properties of the sintered body were characterized. The results show that the microstructure of the sintered alloy is composed of austenite matrix, copper phase and manganese-rich phase. With the increase of Fe₂O₃ content (0~0.8 wt%), the density, tensile strength and total elongation of the high manganese non-magnetic steel increase first and then decrease. When the mass fraction of Fe₂O₃ is 0.4%, the density reaches the highest value of 92.67%, the tensile strength and total elongation are 581 MPa and 8.1 %, respectively. The calculation shows that the tensile strength and total elongation of the high manganese non-magnetic steel increase by 9.4% and 66.7%, respectively, with the addition of 0.4wt % Fe₂O₃, and the strengthening and toughening effect is remarkable. This shows that during the sintering process, Fe₂O₃ powder has a reduction reaction with free graphite C and H₂ in ammonia decomposition. The sintering process of alloy powder is accelerated by activation, and the homogenization of Mn is promoted. At the same time, the closure of pores is promoted, and the density of the alloy is improved.