铌含量对Fe-C-Cr-Nb系表面熔覆金属组织及耐磨性的影响

Effect of Niobium Content on Microstructure and Wear-resistance for Fe-C-Cr-Nb Surface Deposited Materials

目的提高钢表面熔覆层的硬度、耐磨性及其综合性能。方法运用气体保护焊堆焊不同Nb含量的Fe-C-Cr-Nb系表面堆焊材料,采用JmatPro软件模拟计算不同铌含量的熔覆层CCT曲线和平衡冷区曲线,分析铌含量对熔覆组织转变和析出相的影响。运用光学显微镜、扫描电镜和X射线衍射仪观察晶粒尺寸和熔覆组织形貌,并对析出相进行分析。利用洛氏硬度计和滑动摩擦磨损试验机,分别对熔覆金属进行宏观硬度和耐磨性的测定。结果不同铌含量熔覆组织均由马氏体和少量贝氏体组成,基体有大量的MC型碳化物析出。当Nb含量为1.5%时,碳化物弥散分布在熔覆组织中,强化效果最佳,此时硬度最高,为55.3HRC。此外,MC型碳化物有明显的细化晶粒作用,显著提高了熔覆组织的韧性。硬质相与韧性基体的配合,使熔覆组织的耐磨性在铌含量为1.5%时达到最佳。结论通过调整Fe-C-Cr-Nb系表面堆焊材料中铌的含量,可以有效地控制熔覆金属组织类型及碳化物组成和分布,从而提高熔覆层的综合性能。

The work aims to improve the hardness,the wear resistance and the comprehensive performance of the deposited materials on steel.The Fe-C-Cr-Nb surface deposited materials with different contents of Nb were deposited by gas shielded welding.JmatPro was used to simulate the CCT curve and equilibrium cold reign curve of deposited layers with different contents of Nb and analyze the influence of Nb content on transformation and precipitated phase of deposited structure.The optical microscope,scanning electron microscope and X-ray diffractometer were used to observe the grain size,surface morphology and composition of the deposited layer and analyze the precipitated phase.The macro hardness and wear resistance of the deposited metal were tested by rock well hardness tester and sliding friction wear tester.The microstructure of the deposited layer with different contents of Nb consisted of martensite and some bainite and a large number of MC-type carbides were formed in substrate.When the Nb content was 1.5%,the carbides were dispersed in the deposited structure,and the strengthening effect was the best.At this time,the highest hardness was 55.3HRC.In addition,MC-type carbides had an obvious effect on grain enforcement,so it could improve the toughness of the deposition.The combination of the hard phase and the tough matrix allowed the wear resistance of the deposited microstructure to reach the best when the Nb content was 1.5%.By adjusting the content of Nb in the Fe-C-Cr-Nb surface deposited materials,the microstructure of deposited materials and the composition and distribution of carbides are effectively controlled to improve the comprehensive performance of the deposition layer.