材料期刊网

以铌质量分数为0~5％的铁-铬-碳系合金粉块为堆焊材料,采用碳弧堆焊方法在 Q235钢基体上制备了堆焊层,研究了铌含量对堆焊层组织、硬度及耐磨性能的影响.结果表明：铌质量分数在0~5％范围内时,堆焊层均能与 Q235钢基体实现良好的冶金结合；堆焊层的组织由灰黑色基体组织和白色硬质相组成,基体组织主要为马氏体和残余奥氏体,白色的硬质相主要为初生的M7 C3型碳化物、共晶碳化物以及 Cr23 C6；随着铌质量分数从0增加至5％,堆焊层组织逐渐细化,硬质相数量逐渐增多,且分布得更加均匀,堆焊层的硬度先升后降,磨损量先降后升；当铌质量分数为3％时,堆焊层硬度最高,为63 HRC,磨损量最小,为5．5 mg,磨损表面的划痕最浅,且不连续,仅有少量斑点状凹坑,磨损程度最轻.

Using Fe-Cr-C alloy powder block containing 0-5wt% Nb as surfacing material,surfacing layer was prepared on Q235 steel substrate by carbon arc surfacing method,the effects of Nb content on microstructure, hardness and wear resistance of the surfacing layer were studied.The results show that,when mass fraction of Nb was 0-5%,all surfacing layers and base metal (Q235 steel)formed good metallurgical bonding.Microstructure of surfacing layer was composed of gray-black matrix and white hard phase,matrix was composed of martensite and retained austenite,white hard phase was consisted by primary carbides of M7 C3 ,eutectic carbides and Cr23 C6 .With the increase of Nb content from 0 to 5wt%,microstructure of surfacing layer gradually refined,the quantity of hard phase gradually increased and they distributed more evenly;Meanwhile,hardness of surfacing layer increased and then decreased,and wear loss decreast and then increase.When the mass fraction of Nb was 3%,the hardness of surfacing layer was the highest,up to 63 HRC,the wear loss was minimum,only reached to 5.5 mg.When the mass fraction of Nb was 3%,scratch on surfacing layer surface was the shallowest and the scratch was not continuous,only a small amount of spot shape pits on wear surface,and the wear degree of the surfacing layer was lightest.