热处理对选区激光熔化17-4PH不锈钢力学性能的影响  

Effect of Heat Treatment on Microstructure and Mechanical Properties of Selective Laser Melted 17-4PH Stainless Steel

作　　者：秦奉 施麒 刘辛 周舸 陈立佳[1] QIN Feng;SHI Qi;LIU Xin;ZHOU Ge;CHEN Lijia(School of Materials Science and Engineering,Shenyang University of Technology,Shenyang 110870,China;Institute of Materials and Processing,Guangdong Academy of Sciences,Guangzhou 510650,China;Guangdong Provincial Key Laboratory of Metal Toughening Technology and Application,Guangzhou 510650,China;National Engineering Research Center of Powder Metallurgy of Titanium&Rare Metals,Guangzhou 510650,China)

机构地区：[1]沈阳工业大学材料科学与工程学院,沈阳110870 [2]广东省科学院材料与加工研究所,广州510605 [3]广东省金属强韧化技术与应用重点实验室,广州510650 [4]国家钛及稀有金属粉末冶金工程技术研究中心,广州510650

出　　处：《材料研究学报》2021年第8期606-614,共9页Chinese Journal of Materials Research

基　　金：广东省自然科学基金(2018A030313127)。

摘　　要：对选区激光熔化成形的17-4PH不锈钢分别进行真空热处理、热等静压高压淬火处理和组合热处理(热等静压固溶后快淬和马弗炉时效后水冷),在1040℃固溶处理2 h和在480℃时效4 h,观察其显微组织并研究了热处理对其力学性能的影响。结果表明,17-4PH不锈钢由回火马氏体和淬火马氏体组成,热处理后沉淀相弥散分布于晶粒内部,其颗粒尺寸为100~150 nm。真空热处理使合金内部孔隙的尺寸减小到3~7μm,而热等静压使内部孔隙几乎完全闭合,使钢的密度基本上达到理论值。真空热处理+水淬使沉积态17-4PH不锈钢的抗拉强度和硬度都显著提高(分别提高到1300 MPa和448.5HV);热等静压在提高沉积态17-4PH不锈钢抗拉强度的同时使其延伸率显著提高到22.4%。断口分析结果表明,沉积态和热等静压样品的断口形貌为典型的韧性断裂,热等静压样品的韧窝更深、尺寸更大。真空热处理和组合热处理样品的断口形貌具有部分脆性断裂的特征且出现裂纹,与沉积态相比塑性略有降低。The laser selectively melted 17-4PH stainless steel was subjected to different post-heat treatment,i.e.vacuum heat treatment(1040℃/2 h+water quenching and 480℃/4 h+water quenching),hot isostatic pressing heat treatment(1040℃-150 MPa/2 h HIP+gas rapid cooling and vacuum 480℃-100 MPa/4 h+GRC)and combined heat treatment(1040℃-150 MPa/2 h HIP+GRC and vacuum 480℃/4 h+water quenching).Afterwards,the microstructure and mechanical performance of the laser melted steels were characterized by means of optical microscopy,electron scanning microscopy,microhardness tester and universal tensile tester.The results show that the vacuum heat treatment can reduce the inner pore size down to 3~7μm.After hot isostatic pressing treatment,all pores almost closed and the density is almost of the theoretical value of the laser deposited 17-4PH stainless stee.After heat treatment,the 17-4PH stainless steel composed of tempered-and quenched-martensite,and the precipitates with size of 100~150 nm dispersed in grains.Vacuum heat treatment+water quenching can significantly increase the tensile strength and hardness of the deposited 17-4PH stainless steel to 1300 MPa and 448.5HV,respectively.Hot isostatic pressing heat treatment can significantly increase the tensile strength of the deposited 17-4PH stainless steel,at the same time,its elongation at break reaches 22.4%.The fracture morphology of the as deposited 17-4PH SS and the one after hot isostatic pressing heat treatment was typical ductile fracture,and the dimples of hot isostatic pressing heat treatment ones were larger in size and deeper in depth.The fracture morphologies of the deposited 17-4PH SS after vacuum heat treatment and combined heat treatment have the characteristics of partial brittle fracture and emergence of a few cracks,whilst who's plasticity decreases slightly,in comparison with that of the as deposited ones.

关 键 词：金属材料 激光选区熔化 热等静压 17-4PH钢 力学性能 

分 类 号：TG142.14[一般工业技术—材料科学与工程]