Effects of Laser Surface Remelting on the Microstructure and Hardness of Laser Deposited Co-285+WC Coatings
The laser deposited Co-285 +WC coating on the 1018 mild steel was remelted by a CW CO2 laser. Microstructure, composition and microhardness distribution along the cross section of the samples were analyzed using scanning electron microscopy (SEM) with energy dispersive X-ray spectrometry (EDX), an X-ray diffractometer (XRD) and a microhardness tester. Results indicate that more WC particles dissolved into the remelting layer, which had a more uniform structure than the as-deposited coating did. The coral-structured remelting layer was pore and crack free, differentiating itself from the as-deposited coating which had a dendrite structure with certain various shaped third phases. There was a sharp increase of W content and a sharp decrease of Co, Cr and Ni contents in the re-melted layer close to the interface between the as-deposited coating and the remelting layer. Elements distribution in the remelting layer was uniform. The microhardness of the remelting layer was 936HV0.5, while that of the as-deposited coating was 770HV0.5. The re-melt of WC particles, re-distribution of W and C elements and the formation of large area W-rich coral-structured phases contributed to the increase of hardness in the remelting layer.
laser-aided direct metal deposition laser remelting Co-285 super alloy microstructure microhardness
SUN Gui-fang LIU Chang-sheng
Key Laboratory for Anisotropy and Texture of Materials of Ministry of Education,Northeastern Univers Key Laboratory for Anisotropy and Texture of Materials of Ministry of Education,Northeastern Univers
国际会议
The Fourth Asian Conference on Heat Treatment and Surface Engineering(第四届亚洲热处理及表面工程大会)
北京
英文
591-595
2009-10-27（万方平台首次上网日期，不代表论文的发表时间）