摘要
目的针对海工装备承载件长期在海洋服役环境中的应力腐蚀失效问题,提高海工装备在海洋服役环境下的抗应力腐蚀性能,研究了激光功率对高熵合金熔覆层组织演变及抗应力腐蚀的影响。方法利用激光熔覆技术在42CrMo钢表面制备CoCrNiMo_(0.5)Nb_(0.2)熔覆层,采用扫面电子显微镜对其组织形貌进行观察,采用恒载浸泡实验和慢应变速率拉伸实验对其抗应力腐蚀性能进行表征。结果不同激光功率制备的CoCrNiMo_(0.5)Nb_(0.2)高熵合金熔覆层呈现共晶组织形态,其中1100 W功率下熔覆层共晶组织较为致密;在恒载作用下,不同激光功率制备的涂层均表现出较为优异的抗应力腐蚀性能,且经过恒载浸泡实验后,涂层与基体的结和仍然较好;随着激光功率的增加,涂层的应力腐蚀敏感性呈先减小后增大的趋势,激光功率1100 W时制备的涂层具有最低的应力腐蚀敏感性,为3.92%;激光功率1000 W制备的涂层其敏感性指数为8.66%,激光功率1200 W制备的涂层其敏感性指数为15.38%。结论激光功率对高熵合金熔覆层的组织演变及抗应力腐蚀性能有较大的影响,激光功率通过涂层影响共晶组织的形成,从而影响其抗应力腐蚀性能,适当的激光功率可以促进共晶组织的形成,具有良好致密共晶组织的涂层其抗应力腐蚀性能相对较好,不同激光功率制备的涂层均具有较好的抗应力腐蚀性能,均未出现明显的应力腐蚀倾向。
42CrMo steel is commonly used as load-bearing components in marine equipment,so it has a significant tendency to suffer stress corrosion in the long-term marine service environment.High-entropy alloys are a new type of multi-component alloy that exhibits excellent properties such as high strength,high hardness,wear resistance,resistance to high-temperature oxidation,and corrosion resistance.Laser cladding technology,as a new type of surface modification technology,is one of the ways to prepare high-entropy alloy cladding layer,which is characterized by fast heating speed,high solidification rate,small heat-affected zone and low dilution rate.The work aims to prepare CoCrNiMo0.5Nb0.2 cladding layer on the surface of 42CrMo steel with laser cladding technology under different laser powers,and the surface of the cladding layer prepared under each laser power is relatively flat,which is in line with the requirements of the subsequent test.Firstly,its microstructure and phase composition were observed,and it was determined that the CoCrNiMo0.5Nb0.2 high-entropy alloy fused cladding layers prepared under different laser powers were composed of FCC phases,Laves phases and a small amount of BCC phases,and the layer microstructures all showed eutectic morphology,and the appropriate laser power could promote the formation of eutectic microstructures,in which the eutectic microstructure of the fused cladding layer under the power of 1100 W was denser.Secondly,the electrochemical test showed the corrosion resistance of the layer and the effect of the laser power on the corrosion resistance.Good eutectic microstructure was to some extent conducive to enhancing the corrosion resistance of the layer.Finally,the stress-corrosion properties were characterized by three-point stress loading immersion experiment and slow strain rate tensile(SSRT)experiment.The corrosion of the layer at three-point stress loading immersion was mainly dominated by pitting corrosion,in which the layer prepared at 1100 W laser power showed less surface corrosion after the corrosion immersion experiment,and the layer prepared at 1200 W laser power showed smaller stress corrosion cracks in the immersion period of 21 days-28 days.Under the action of dead load,the layers prepared by different laser powers showed excellent stress-corrosion resistance,and the harmony between the layer and the matrix junction was still good after the dead load immersion test.With the increase of laser power,the stress-corrosion resistance of the layer showed a trend of increasing and then decreasing.The layer prepared at 1100 W laser power had the lowest stress-corrosion sensitivity of 3.92%.The sensitivity index of the layer prepared at 1000 W laser power was 8.66%,and the sensitivity index of the layer prepared at 1200 W laser power was 15.38%.The layers prepared at different laser powers all have less surface corrosion after corrosion immersion and good stress-corrosion resistance.The fracture morphology of the tensile specimens is deconvoluted fracture and quasi-deconvoluted fracture,and the fracture form is brittle fracture.Through the analysis of the above results,it can be seen that the laser power can affect the formation of the eutectic microstructure,thus affecting its corrosion resistance and mechanical properties,further affecting the resistance of the material to stress corrosion,so the layer with a dense and good eutectic microstructure has better resistance to stress corrosion.
作者
宋涛
姜芙林
魏长生
张耀辉
杨发展
梁鹏
SONG Tao;JIANG Fulin;WEI Changsheng;ZHANG Yaohui;YANG Fazhan;LIANG Peng(School of Mechanical and Automotive Engineering,Qingdao University of Technology,Shandong Qingdao 266520,China;Collaborative Innovation Center for Mechanized Production Equipment of Major Crops in Shandong Province,Shandong Qingdao 266109,China)
出处
《表面技术》
北大核心
2025年第12期85-96,共12页
Surface Technology
基金
山东省自然科学基金资助项目(ZR2022MEE081,ZR2021ME198)
山东省主要农作物机械化生产装备协同创新中心开放课题项目(SDXTZX-21)
高等学校学科创新引智计划资助(D21017)。
关键词
激光熔覆
高熵合金
激光功率
共晶组织
应力腐蚀
laser cladding
high-entropy alloy
laser power
eutectic microstructure
stress corrosion
