40Cr表面梯度晶体缺陷促进包埋渗Al涂层的组织及性能  

Microstructure and Performance of Aluminized Coatings Prepared by Pack-cementation Promoted by Surface Gradient Crystal Defects on 40Cr Steel

作　　者：胡建军[1,2] 王蝶 郭宁[3] 杨显 李晖[1] 许洪斌[2] HU Jianjun;WANG Die;GUO Ning;YANG Xian;LI Hui;XU Hongbin(College of Materials Science and Engineering,Chongqing University of Technology,Chongqing 400054;Chongqing Municipal Key Laboratory of Institutions of Higher Education for Mould Technology,Chongqing University of Technology,Chongqing 400054;School of Materials and Energy,Southwest University,Chongqing 400715)

机构地区：[1]重庆理工大学材料科学与工程学院,重庆400054 [2]重庆理工大学模具技术重庆市高校重点实验室,重庆400054 [3]西南大学材料与能源学院,重庆400715

出　　处：《机械工程学报》2023年第6期114-122,共9页Journal of Mechanical Engineering

摘　　要：包埋渗Al工艺是改善40Cr钢耐蚀性能的有效且经济的方法之一。在传统包埋渗铝(Al)法的工艺前加入扭转预变形,在40Cr钢引入高密度晶体缺陷增加扩散通道来提高包埋渗工艺中Al原子的扩散速率,从而达到降低加热温度、提高材料综合性能的目的。研究扭转工艺对晶粒取向、晶界、局部取向差的影响,表征扩散渗Al后试样的微观组织,测试硬度和耐腐蚀性能,分析不同温度(600℃、650℃、700℃及750℃)对渗层组织与性能的影响。研究结果表明:扭转变形在40Cr表面引入高密度晶体缺陷,可提高扩渗效率,增大渗层厚度;温度越高,渗层越厚,晶粒尺寸越大,组织的不均匀性增强,硬度越低。750℃时其渗层上存在较多的孔洞,对耐腐蚀性造成一定的影响,700℃试样耐腐蚀性能最优。The pack-cementation aluminizing process is considered to be one of the most effective and economical methods to improve the corrosion resistance of steels.In this work,pre-torsion deformation combined with the pack-cementation aluminizing was conducted to prepared Al-coatings on the 40Cr steel.The steels were twisted prior to the aluminizing process,which can introduce high-density crystal defects into the steel surface,and increases the diffusion channels and thereby improving the diffusion rate of Al atoms during the aluminizing process.Microstructure of the samples before and after aluminizing was characterized systematically.The microhardness and corrosion resisting property were measured.The effects of pack-cementation temperatures(600,650,700 and 750℃)on the microstructure and properties of Al-coating were analyzed.The results show that the pre-torsion deformation introduces high-density crystal defects on the surface of 40Cr,which can improve the diffusion efficiency and increase the thickness of the infiltration layer.The higher the temperature,the thicker the infiltration layer,but the larger the grain size,the stronger the inhomogeneity of the structure and the lower the hardness.From 600 to 700℃,the corrosion resistance is gradually enhanced due to the thickening of the coating,but when the temperature reaches 750℃,more holes appear in the infiltrated layer,resulting in poor corrosion resistance.In contrast,the 700℃sample is resistant to the best corrosion performance.

关 键 词：40CR钢 包埋渗铝 梯度晶体缺陷 预扭转变形 铝涂层 

分 类 号：TG156[金属学及工艺—热处理] TB31[金属学及工艺—金属学]