基体预热对激光熔覆制备M2钢熔覆层表面硬度均匀性的影响  

Effect of Substrate Preheating on Surface Hardness Uniformity of M2 Steel Cladding Layer Prepared Through Laser Cladding

作　　者：刘立培 陈皓 杨仁人 林英华[1] 彭龙生 彭宇霄 王新林[1] Liu Lipei;Chen Hao;Yang Renren;Lin Yinghua;Peng Longsheng;Peng Yuxiao;Wang Xinlin(Hunan Province Key Laboratory for Ultra-Fast Micro/Nano Technology and Advanced Laser Manufacture,College of Mechanical Engineering,University of South China,Hengyang 421001,Hunan,China;Hunan Lifang Roller Co.,Ltd.,Hengyang 421681,Hunan,China;Hunan Advanced Manufacturing Engineering Technology Research Centerfor High Wear-Resistant Alloy Materials,Hengyang 421681,Hunan,China)

机构地区：[1]南华大学机械工程学院超快微纳技术与激光先进制造湖南省重点实验室,湖南衡阳421001 [2]湖南力方轧辊有限公司,湖南衡阳421681 [3]湖南省高耐磨合金材料先进制造工程技术研究中心,湖南衡阳421681

出　　处：《中国激光》2024年第20期88-102,共15页Chinese Journal of Lasers

基　　金：湖南省自然科学基金-省市联合基金(2022JJ50019);福建省技术创新重点攻关及产业化项目(2023XQ017);衡阳市指导性计划(hyzdxjh202101);南华大学人才引进项目(210XQD017)。

摘　　要：研究了基体预热对M2钢熔覆层表面硬度均匀性的影响,利用数学标准差方法表征了熔覆层表面硬度均匀性。结果表明:基体预热前,熔覆层表面凸起明显,组织结构为柱状晶和等轴晶混合组织,表面显微硬度极差为448.2 HV,硬度波动系数达83;基体预热后,熔覆层表面平整度变好,组织结构转变为单一形态树枝晶,表面显微硬度极差为176.1 HV,硬度波动系数降低到46.3。通过温度场数值模拟,发现基体预热使熔池峰值温度提高,但在中心到边缘区间,温度梯度在熔池凝固过程中降低;通过残余应力数值模拟,发现基体预热不仅降低熔覆层内残余应力,还降低熔覆层内残余应力的波动幅度。最后,结合温度场、应力场模拟结果及组织结构,探讨了基体预热对熔覆层表面硬度均匀性的影响机理。Objective The forming quality of high-precision stainless steel sheets during cold rolling is directly affected by the uniformity of the surface hardness of Cr12MoV cold rolling work rolls.Therefore,enhancing the surface hardness uniformity of cold rolling work rolls has consistently been a focal point of research and development for rolling mill manufacturers worldwide.Laser cladding technology,which is a core element of green manufacturing,has been widely used for the surface strengthening and repair of rolling mill rolls.However,cladding layers are prone to developing defects,such as cracks,owing to the significant thermal stresses and element segregation that occur within them because of the rapid heating and cooling during laser cladding.Currently,many scholars often use substrate preheating methods to address this issue.However,studies investigating on whether substrate preheating can enhance the surface hardness uniformity of cladding layers are limited,particularly in the context of M2 steel.In this study,we introduce a substrate preheating process in laser cladding experiments to improve the surface hardness uniformity of cladding layers.Through numerical simulations of temperature and stress fields,coupled with microstructural analysis,we explore the impact of substrate preheating on the surface hardness uniformity of cladding layers.Methods Single-track M2 steel cladding layers are prepared on both preheated and unheated Cr12MoV roll substrates through laser cladding.First,the forming qualities of the cladding layers prepared using the two processing methods are compared.Second,the microstructure characteristics of the cross-sectional and longitudinal sections of the cladding layers are examined using metallographic microscope,with a comparative analysis of the structures at the same depth within the cladding layers.Third,X-ray diffraction is used to compare and analyze the phase composition of the cladding layers.Subsequently,the surface hardness of the cladding layers is measured at 3×10 locations u

关 键 词：CR12MOV 激光熔覆 M2钢 预热 硬度均匀性 数值模拟 

分 类 号：TG174.4[金属学及工艺—金属表面处理]