Abstract：MIM 17-4PH stainless steel was prepared at 1 260, 1 290 and 1 305 ℃ using nitrogen sintering technology in the whole process. The microstructure and properties of the stainless steel were tested and analyzed, which were compared with MIM 17-4PH stainless steel prepared by conventional sintering process of vacuum and argon sintering. The results show that the MIM 17-4PH sintering in a nitrogen atmosphere throughout the process facilitates the nitriding effect. Compared to the conventional sintering process with vacuum and argon, the whole sintering process under nitrogen decreases its relative density, while the grains are obviously refined and new microstructure appears. Meanwhile, the content of austenite in sintered stainless steel decreases with the increase of sintering temperature. 1 290 ℃ is the best temperature to make sample possess relatively higher densification, better nitriding effect, refined grain size, and uniform distribution of fine second phase. The nitrogen sintering improves the comprehensive mechanical properties compared with vacuum and argon sintering. The tensile strength increases from 900 MPa to 1 158 MPa. The elongation increases from 6% to about 10%, and cross-sectional hardness (HRC) increases from 20.2 to 28.0.
[1] 王帅, 卢志江, 杨春光, 等. 17-4PH不锈钢的抗菌性能[J]. 材料研究学报, 2014, 28(1): 15-22. WANG Shuai, LU Zhijiang, YANG Chunguang, et al.Antibacterial performance of 17-4PH stainless steel[J]. Chinese Journal of Materials Research, 2014, 28(1): 15-22. [2] 喻建, 李益民, 李东阳, 等. 粉末装载量对金属注射成形17-4PH不锈钢力学性能的影响[J]. 粉末冶金材料科学与工程, 2018, 23(1): 32-37. YU Jian, LI Yimin, LI Dongyang, et al.Effect of powder loading on mechanical properties of metal injection molding 17-4PH stainless steel[J]. Materials Science and Engineering of Powder Metallurgy, 2018, 23(1): 32-37. [3] CAPUS J, EDITOR C.MIM2019 conference report: Worldwide confidence persists[J]. Metal Powder Report, 2019, 74(4): 192-198. [4] CAPUS J.MIM2018 Conference report: Continuing positive outlook[J]. Metal Powder Report, 2018, 73(3): 133-137. [5] DEHGHAN-MANSHADI A, BERMINGHAM M J, DARGUSCH M S, et al.Metal injection moulding of titanium and titanium alloys: Challenges and recent development[J]. Powder Technology, 2017, 319: 289-301. [6] KAFKAS F, EBEL T.Metallurgical and mechanical properties of Ti-24Nb-4Zr-8Sn alloy fabricated by metal injection molding[J]. Journal of Alloys and Compounds, 2014, 617: 359-366. [7] OBASI G C, FERRI O M, EBEL T, et al.Influence of processing parameters on mechanical properties of Ti-6Al-4V alloy fabricated by MIM[J]. Materials Science and Engineering A, 2010, 527(16/17): 3929-3935. [8] ESFANDIARI M, DONG H.The corrosion and corrosion-wear behaviour of plasma nitride 17-4PH precipitation hardening stainless steel[J]. Surface and Coatings Technology, 2007, 202: 466-478. [9] YE H, YANG X, HONG H.Sintering of 17-4PH stainless steel feedstock for metal injection molding[J]. Materials Letters, 2008, 62: 3334-3336. [10] 阮建明, 黄培云. 粉末冶金原理[M]. 北京: 机械工业出版社, 2012. RUAN Jianming, HUANG Peiyun.Principle of Powder Metallurgy[M]. Beijing: China Machine Press, 2012. [11] 杜锦铮, 路媛媛, 陈浩, 等. 17-4PH不锈钢透平叶片激光固溶时效强化的力学性能[J]. 中国表面工程, 2018, 31(3): 9-16. DU Jinzheng, LU Yuanyuan, CHEN Hao, et al.Mechanical properties of 17-4PH stainless turbine blades by laser solution and aging[J]. China Surface Engineering, 2018, 31(3): 9-16. [12] CHUNG C Y, TZENG Y C.Effects of aging treatment on the precipitation behavior of ε-Cu phase and mechanical properties of metal injection molding 17-4PH stainless steel[J]. Materials Letters, 2019, 237: 228-231. [13] 刘宗昌, 计云萍. 贝氏体组织结构辨识方法(一)[J]. 热处理技术与装备, 2018, 39(5): 1-7. LIU Zongchang, JI Yunping.Identification methods of bainitic microstructure (I)[J]. Heat Treatment Technology and Equipment, 2018, 39(5): 1-7. [14] 崔大伟, 曲选辉, 魏文庆, 等. 高氮奥氏体钢粉末的合成及其致密化工艺[J]. 材料热处理学报, 2013, 34(12): 45-52. CUI Dawei, QU Xuanhui, WEI Wenqing, et al.Synthesis and densification process of high nitrogen austenitic steel powders[J]. Transaction of Materials and Heat Treatment, 2013, 34(12): 45-52. [15] Federation M P I. MPIF 35-2016, Materials standards for metal injection molded parts[S]. USA: Metal Powder Industry Federation, 2016. [16] 付华, 张光磊. 材料性能学[M]. 北京: 北京大学出版社, 2010. FU Hua, ZHANG Guanglei.Properties of Materials[M]. Bingjing: Peking University Press, 2010.
2020, Vol. 25 
