钼对高铬铸铁激光熔覆层组织和硬度的影响

Influence of Mo on microstructure and hardness of high Cr cast iron laser cladding layer

在两种不同的扫描速度下(100 mm/min、300 mm/min),在20钢基体表面激光熔覆钼粉与高铬铸铁复合粉末,利用扫描电子显微镜、维氏硬度计检测了不同钼粉含量时(0.5%、3%、5%、7.5%、10%)熔覆层的显微组织和硬度。结果表明,钼粉与高铬铸铁复合粉末经激光熔覆后,晶粒细化,组织致密,无裂纹、气孔等缺陷;在100 mm/min较低的扫描速度下,加入钼后,能细化晶粒,促进条状珠光体向胞状奥氏体枝晶转变,不同钼含量下熔覆层的平均硬度分别为160、172、193、212和226 HV0.2;在300 mm/min较高的扫描速度下,钼加入后,能抑制碳化物生长,促进长条状的初生合金碳化物向方块状、层片状的碳化物转变,有利于抑制开裂。不同钼含量下熔覆层的平均硬度分别为586、612、637、682和712 HV0.2。

Molybdenum（ Mo） and high-Cr cast iron mixed powder was laser cladded on the surface of 20 steel substrate under two different scanning speed（ 100 mm/min and 300 mm/min）,and microstructure and hardness of the laser cladding layer with different Mo contents（ 0. 5%,3%,5%,7. 5% and 10%） were tested by scanning electron microscope and hardness tester,respectively. The results show that the Mo and high-Cr cast iron laser cladding layer has better properties such as finer grains,higher density without crack and gas hole. When the scanning speed is slower（ 100 mm/min）,the adding of Mo make the crystal grain smaller,the long striped pearlite changed into cellular dendritic austenite. Under different Mo contents,the average hardness of cladding layer is 160,172,193,212 and 226 HV0. 2,respectively. When the scanning speed is faster（ 300 mm/min）,the adding of Mo can restrain the growth of carbides and promote long striped original alloy carbides change into square block carbides and lamellar carbides,which is conductive to restrain cracking. Under different Mo contents,the average hardness of cladding layer is 586,612,637,682 and 712 HV0. 2,respectively.