深冷处理对粉末床激光烧结成形的H13钢组织与力学性能的影响

Effect of Cryogenic Treatment on Microstructure and Mechanical Properties of H13 Steel Formed by Laser Sintering in Powder Bed

基于气雾化法制备的H13钢粉体,为提高粉末床激光选区烧结成形(SLM)H13热作模具钢的强韧性,对沉积态样件首先进行“球化退火+油淬+回火(1次)”处理后,然后再进行“-196℃深冷处理研究+2次回火”处理。采用光学显微镜(OM)表征不同热处理态试件的微观组织;采用冲击试验机、洛氏硬度计以及显微硬度计等检测手段对不同热处理状态下的试件的冲击韧性、洛氏硬度、显微硬度进行了检测。结果表明:沉积态试样的硬度低于淬火态试样的硬度,而且淬火态试样马氏体板条轮廓清晰;试样经深冷处理后洛氏硬度平均提升1.5HRC;随深冷时间的延长,冲击韧性有逐渐降低的趋势。

Based on 15-53μm H13 steel particle made by gas atomization method,H13 steel samples were formed by powder bed laser sintering(SLM),whose parameters is as follows:the diameter of optical plate of 0.1 mm,the scanning distance of 0.1 mm,the scanning speed of 760 mm/min,the laser power of 320w and the powder thickness of 0.05 mm.In order to improve the strength and toughness of powder bed laser sintering(SLM)H13 hot working die steel,the deposited samples were first treated with“spherodizing annealing+oil quenching+tempering(once)”,and then with“-196℃cryogenic treatment+twice tempering”treatment.Optical microscopy(OM)was used to characterize the microstructure of specimens in different heat treatment states.The impact toughness,Rockwell hardness and microhardness of specimens under different heat treatment conditions were tested by impact testing machine,Rockwell hardness tester and microhardness tester.The results show that the hardness of the deposited specimens is lower than that of the quenched specimens,and the martensitic slats of the quenched specimens are clear,the Rockwell hardness of the samples increased by 1.5HRC on average after cryogenic treatment,and the impact toughness decreased gradually with the extension of cryogenic time.