激光激发氨气对38CrMoAl钢渗氮微观组织和硬度的影响(特邀)  

Effects of laser excited ammonia on microstructure and hardness properties of nitriding 38CrMoAl steel(invited)

作　　者：范丽莎 包旭 王廷斌 吴岭 张硕文 赵天真 孙涛清 冉磊 姚建华 FAN Lisha;BAO Xu;WANG Tingbin;WU Ling;ZHANG Shuowen;ZHAO Tianzhen;SUN Taoqing;RAN Lei;YAO Jianhua(Institute of Laser Advanced Manufacturing,Zhejiang University of Technology,Hangzhou 310023,China;College of Mechanical Engineering,Zhejiang University of Technology,Hangzhou 310023,China;Collaborative Innovation Center of High-End Laser Manufacturing Equipment,Hangzhou 310023,China)

机构地区：[1]浙江工业大学激光先进制造研究院,浙江杭州310023 [2]浙江工业大学机械工程学院,浙江杭州310023 [3]高端激光制造装备省部共建协同创新中心,浙江杭州310023

出　　处：《红外与激光工程》2024年第11期52-63,I0003,共13页Infrared and Laser Engineering

基　　金：国家重点研发计划项目(2023YFB4606000);国家自然科学基金项目(52205502);浙江省“尖兵”、“领雁”研发攻关项目(2024C01130)。

摘　　要：38CrMoAl钢由于其具有良好的渗氮工艺性,渗氮后常用于轴、齿轮、螺杆等零件,但常规气体渗氮工艺渗氮周期长、渗氮效率低。为提高38CrMoAl钢的渗氮效率和硬度性能,文中搭建了激光激发辅助渗氮实验平台,制备了气体渗氮和激光辅助渗氮试样。研究了激光功率对渗氮试样表面微观组织形貌、氮化物颗粒尺寸、表面粗糙度、氮元素含量以及截面化合物层、扩散层等微观组织形貌的影响规律,并开展了激光辅助渗氮试样的硬度性能分析测试。结果表明:随着渗氮的进行,38CrMoAl钢试样表面经历了α-Fe到γ′-Fe4N再到ε-Fe_(2~3)N的相变。激光激发氨气辅助渗氮中,表面的氮化物颗粒平均尺寸、表面粗糙度、氮元素含量均随着激光功率的增加而增大。采用电子探针X射线显微分析仪(Electron Probe X-ray Micro Analyzer,EPMA)对渗氮试样截面氮元素分布的元素线扫分析结果表明,随着激光功率的增加,渗氮层内部20μm厚度内的氮含量随激光功率的增大而提升。未经渗氮处理的38CrMoAl钢表面平均硬度为256 HV_(0.1);经过气体渗氮后,表面硬度提升至788 HV_(0.1);经过激光激发氨气辅助渗氮后,表面硬度最高可达1102 HV_(0.1)。渗氮试样截面渗氮层硬度随着层深的增加而逐渐降低,最终与基体硬度接近。研究表明:通过引入激光激发氨气分子,可以有效促进渗氮过程中的氨气分解,提高氨气利用率,提高渗氮效率,提升试样的硬度。Objective Nitriding is a common process in the chemical heat treatment of 38CrMoAl steel,which alters the chemical composition and microstructure of the steel surface.It is widely applied to components such as shafts,gears,screws,and hydraulic plungers that operate in harsh environments.By directly coupling laser energy to ammonia molecules through resonant exciting their vibrational modes,the dissociation of active nitrogen atoms from ammonia can be accelerated,reducing heat dissipation during transfer.This enhances the efficient dissociation of ammonia molecules and increases the likelihood of ammonia absorption on the sample surface,leading to a deeper nitrided layer and improved hardness properties.To address the challenges of long treatment times and low efficiency in traditional gas nitriding,lasers were introduced into the gas nitriding process of 38CrMoAl steel.The effect of laser power on the microstructure and hardness of the nitrided samples was analyzed,providing valuable insights for the efficient production of high-quality nitrided layers on 38CrMoAl steel.Methods The experimental platform for laser-assisted nitriding(Fig.1(a))consists primarily of a CO_(2) infrared laser,a vacuum chamber,vacuum system,a temperature control system,and an ammonia supply system.The experimental material used was tempered and heat-treated 38CrMoAl steels.Using the developed equipment,gas nitriding and laser-assisted nitriding experiments were conducted at laser powers of 50 W,100 W,150 W,and 200 W.After the experiments,the cross-sections of the nitrided samples were polished and etched.The surface microstructure was analyzed using an XRD(X-ray diffraction),SEM(Scanning electron microscope),and shape measurement laser microsystem,while the cross-sectional microstructure was examined with an optical microscope.Chemical composition was determined through EDS(Energy-dispersive spectroscopy)and EPMA(Electron probe X-ray micro analyzer)analysis.In addition,the surface hardness and cross-sectional hardness of the nitrided sam

关 键 词：38CRMOAL钢 激光激发 渗氮 硬度性能 

分 类 号：TN249[电子电信—物理电子学]