45#钢表面激光合金化NiCr-Al2O3涂层的组织及耐磨性能研究  

Microstructure and Wear Resistance of NiCr-Al2O3 Coating Alloyed with 45# Steel Laser

作　　者：刘通[1] 孙桂芳[1] 张永康[1] 

机构地区：[1]东南大学,南京211189

出　　处：《表面技术》2016年第10期64-69,共6页Surface Technology

基　　金：国家自然科学基金(51201070);国家博士后基金(2015M570395);江苏省产学研项目(BY2015070-05);江苏省博士后基金(1501028A)~~

摘　　要：目的提高平模制粒机中平模的耐磨性能。方法采用激光合金化技术在45#钢表面制备不同比例混合的NiCr-Al_2O_3合金化层。利用X射线衍射仪(XRD)、扫描电子显微镜(SEM)及附带的能谱仪(EDS)分析了合金化层的物相组成和显微组织,用FM-700自动显微硬度仪测量合金化层的硬度变化规律,用屏显式磨损试验机研究测试了合金化层的耐磨性能。结果合金化层主要由马氏体组成,且弥散分布着不同数量的未熔Al_2O_3颗粒,热影响区由马氏体和残余奥氏体组成。激光合金化层的主要物相为奥氏体和马氏体,Al_2O_3含量越多,马氏体相越多,而奥氏体相越少。合金化层的厚度约为0.9 mm,表面硬度大约是基材的2.4倍,表面耐磨性是基材的6倍以上。在一定范围内,合金化层中Al_2O_3颗粒的含量越高,平均显微硬度越大且更加均匀,耐磨性越好。热影响区的硬度变化均匀,起到了很好的过渡作用。磨损机理主要是犁削磨损,Al_2O_3颗粒的存在可以减少磨粒对基体的犁削作用。结论在45#钢表面激光合金化NiCr-Al_2O_3混合涂层可以有效提高基体表面的硬度和耐磨性,Al_2O_3颗粒含量达30%时可以获得高硬度、高耐磨性且均匀的合金化层。The work aims to improve wear resistance of the flat die in flat-die pelletizer. The alloyed layer of NiCr-Al_2O_3mixed in different ratios was fabricated on 45~# steel by laser alloying technology. Phase composition and microstructure of the alloyed layer were characterized by X-ray diffractometer（XRD）, scanning electron microscope（SEM） and energy disperse spectroscopy（EDS）. Hardness change law of the alloyed layer was measured by FM-700 automatic micro-hardness tester. The wear resistance was investigated by screen display type abrasion tester. The experimental results indicated that the alloyed layer was mainly composed of martensite. Different fractions of undissolved Al_2O_3 particles were distributed dispersively in the alloyed layer. The heat-affected zone consisted of martensite and retained austenite. Primary phases of the alloyed layer were austenite and martensite. As the content of Al_2O_3 particles increased, the phase of martensite increased and the phase of austenite decreased. Thickness of the alloyed layer was approximately 0.9 mm. Surface micro-hardness value of the alloyed layer was nearly 2.4 times of that of the substrate and surface wear resistance was more than 6 times of that of the substrate. To some extent, the higher the content of Al_2O_3 particles in alloyed layer was, the greater the average micro-hardness of the alloyed layer and the better the wear resistance would be. The micro-hardness varied uniformly in the heat-affected zone, which provided a transition zone between the alloyed layer and the substrate. Wear mechanism was mainly plough wear, the existence of Al_2O_3 particles might reduce ploughing of abrasive particles on the substrate. The hardness and the wear resistance can be effectively improved by laser alloying Al_2O_3-NiCr mixed coating on 45~# steel. Uniform alloyed surface with high hardness and wear resistance can be fabricated by laser alloying with NiCr ＋ 30% Al_2O_3 particles.

关 键 词：激光合金化 45#钢 AL2O3 显微组织 显微硬度 耐磨性能 

分 类 号：TH117.1[机械工程—机械设计及理论]