DZ17G定向凝固高温合金的微激光冲击强化方法与疲劳试验研究  

Micro-scale Laser Shock Peening Method and Fatigue Test of DZ17G Directionally Solidified Superalloy

作　　者：聂祥樊[1] 李应红[1] 何卫锋[1] 徐凌志[2] 罗思海[1] 李翔[1] 李一鸣[1] 田乐[1] Nie Xiangfan1, Li Yinghong1, He Weifeng1, Xu Lingzhi2, Luo Sihai1, Li Xiang1, Li Yimingl, Tian Le1(1. Science and Technology on Plasma Dynamics Laboratory, Air Force Engineering University, Xi＇an 710038, China;2. Beijing Power Machinery Institute, Beijing 100074, China)

机构地区：[1]空军工程大学等离子体动力学重点实验室,陕西西安710038 [2]北京动力机械研究所,北京100074

出　　处：《稀有金属材料与工程》2018年第10期3141-3147,共7页Rare Metal Materials and Engineering

基　　金：国家重点基础研究发展计划(2015CB057400);国家自然科学基金(51505496)

摘　　要：针对航空发动机涡轮叶片疲劳断裂问题,对DZ17G定向凝固合金模拟叶片进行激光冲击强化处理。为了防止剧烈塑性变形导致定向柱状晶发生细化,提出基于微激光冲击强化系统的水下无吸收保护层高频冲击方法,采用短脉宽、微尺度激光降低塑性变形程度和深度,采用无吸收保护层的高频冲击方式获得均匀形变强化层。对比考核了未强化与强化态试样的显微硬度和高周振动疲劳性能。结果表明:DZ17G模拟叶片经微激光冲击后浅表层内仅形成了高密度位错和位错缠结等结构,未发生晶粒细化,而且位错密度随深度增加而快速降低;高密度位错集聚缠结使表面硬度提高幅度达30%,但硬化层深度仅为180μm。DZ17G模拟叶片疲劳强度由257.00 MPa提高到302.00 MPa,提高幅度达17.5%,而且800℃下保温2 h后仍有11.7%的提高。其中高密度位错和位错缠结是疲劳性能提高的内在原因。Aiming at the fatigue fracture fault of aero-engine turbine blades,laser shock peening was conducted on the DZ17G directionally solidified superalloy simulated blades to improve fatigue performance.However,in order to avoid the occurrence of grain refinement in the columnar crystals,an underwater high frequency laser shock method without ablation coating based on micro-scale laser shock peening was proposed.In this method,a short laser pulse width micro-scale laser beam was conducted to decrease the plasticity degree and affected depth,and high frequency shock without ablation coating was conducted to form a uniform plastic strengthening layer.The microhardness and high-cycle fatigue performance of the original sample and the strengthening sample were comparatively examined.The results indicate that there are high density dislocations and dislocation tangles generated in the shallow layer of DZ17G superalloy simulated blades,but no grain refinement occurs,and the density of dislocations decreases sharply with the increase of depth.High density dislocations and dislocation tangles result in a high improvement of hardness,increased by 30%.However,a hardened layer of 180μm in thick is generated.The fatigue strength of the DZ17G superalloy simulated blades increases form 257.00 MPa to 302.00 MPa,increased by 17.5%.There is still an improvement of 11.7%in fatigue strength after the thermal insulation at 800°C for 2h.High density dislocations and dislocation tangles are the immanent causes for fatigue performance improvement.

关 键 词：DZ17G定向凝固合金 微激光冲击强化 高密度位错 显微硬度 高周疲劳 

分 类 号：TG665[金属学及工艺—金属切削加工及机床]