Mo含量对激光熔覆316L组织和耐蚀性能的影响  

Influence of Mo Content on Microstructure and Corrosion Resistance of Laser-cladded 316L

作　　者：董刚 曾宇[1,2,3] 胡健东 庞靖凯 杨高林 石岳林 张群莉 姚建华 DONG Gang;ZENG Yu;HU Jiandong;PANG Jingkai;YANG Gaolin;SHI Yuelin;ZHANG Qunli;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;Special Equipment Manufacturing and Advanced Processing Technology Key Laboratory of the Ministry of Education/Zhejiang Province,Hangzhou 310023,China;Zhoushan Dingzun Technology Co.,Ltd.,Zhejiang Zhoushan 316000,China)

机构地区：[1]浙江工业大学激光先进制造研究院,杭州310023 [2]浙江工业大学机械工程学院,杭州310023 [3]特种装备制造与先进加工技术教育部/浙江省重点实验室,杭州310023 [4]舟山市鼎尊智能科技有限公司,浙江舟山316000

出　　处：《表面技术》2024年第23期204-215,共12页Surface Technology

基　　金：国家自然科学基金重点项目(52035014);浙江省公益技术应用研究项目(LGG22E050036);舟山科技计划项目(2023C13011)。

摘　　要：目的研究不同Mo添加量对316L熔覆层组织和耐腐蚀性能的影响,进一步提高316L激光熔覆层耐海水腐蚀的能力,以实现高质量的激光再制造修复。方法利用激光熔覆技术和316L不锈钢合金粉末,通过在粉末中添加不同比例的球形Mo粉(质量分数为2%、4%、6%)来制备熔覆层,利用金相显微镜、扫描电子显微镜、激光共聚焦显微镜、X射线衍射仪、电化学工作站对熔覆层的宏观形貌、微观组织、物相组成、元素分布、晶粒取向和耐腐蚀性能进行表征。结果Mo的添加量不超过4%时,熔覆层内的物相并未发生改变,仍由奥氏体组成。当Mo的添加量达到6%时,过冷度增大导致奥氏体向马氏体转变,熔覆层内出现大量未完全熔化的Mo颗粒。随着Mo含量的增加,晶粒在<001>方向的织构强度下降,有向<111>方向生长的趋势。平均晶粒尺寸由235.59μm下降到184.35μm,小尺寸晶粒占比增大,导致位错在晶粒内部积累,熔覆层内位错密度增大。同时,晶粒细化有助于形成更致密的钝化膜。电化学测试中,随着Mo含量的增加,点蚀坑数量明显下降,熔覆层的耐腐蚀性能得到提升。Mo的添加量为4%时,自蚀电流密度较不添加组由8.253×10^(-6) A/cm^(2)减小至4.540×10^(-7) A/cm^(2),钝化电阻由4927Ω·cm^(2)增大到8702Ω·cm^(2),提升约75%。结论在激光熔覆316L时,适量增加Mo元素含量,能够细化晶粒,使得熔覆层表面形成的钝化膜更加致密,提高钝化膜抵抗侵蚀的能力,进一步提升316L熔覆层的耐海水腐蚀能力。To achieve high-quality laser remanufacturing of 316L components,alloying element Molybdenum(Mo)is added during the laser cladding of 316L stainless steel powder to further enhance the corrosion resistance of 316L stainless steel in environments containing chloride ions,such as seawater.In order to study the effects of varying Mo content on the microstructure and corrosion resistance of the 316L cladding layer,laser cladding technology was utilized to fabricate 316L cladding layers with different Mo additions(2wt.%,4wt.%,6wt.%)on a 316L stainless steel substrate.The macroscopic morphology,microstructure,phase composition,elemental distribution,grain orientation,and corrosion resistance of the cladding layers were characterized by metallographic microscopy,scanning electron microscopy,laser confocal microscopy,X-ray diffraction,and an electrochemical workstation.The results indicated that when the addition of Mo element did not exceed 4%,the phase within the cladding layer remained unchanged,still comprising austenitic phases.However,when the Mo addition reached 6%,the substantial incorporation of Mo reduced the stability of austenite in the stainless steel.The increased undercooling altered the solidification conditions of the alloy,causing partial transformation of austenite into martensite,while a significant amount of un-melted Mo particles appeared in the cladding layer.With the increased content of Mo,the texture strength of grains in the<001>direction decreased,showing a tendency to grow towards the<111>direction.Moreover,the grains became refined,with the average grain size in the cladding layer reducing from 235.59μm to 184.35μm.The higher proportion of smaller-sized grains increased the grain boundary area,resulting in the accumulation of dislocations within the grains and enhancing the dislocation density of the cladding layer.The smaller grain size,with its larger grain boundary area,provided more nucleation sites for the growth of the passivation layer and could promote the formation of a uniform an

关 键 词：激光熔覆 316L Mo元素 耐蚀性能 晶粒尺寸 晶粒取向 

分 类 号：TG174[金属学及工艺—金属表面处理]