高铬铸铁芯焊条堆焊层组织分析

Microstructure analysis of hardfacing layer by electrode cored with high chromium casting iron

关键词:  高铬合金铸铁  堆焊焊条  合金过渡系数  堆焊层组织

Key words:  high chromium casting iron  hardfacing electrode  transfer coefficient  microstructure of hardfacing layer

摘要:

基于焊芯过渡合金元素的技术思路,研制了高铬合金铸铁同质堆焊焊条.分析了不同药皮堆焊焊条的堆焊层组织及性能,定量表征了合金元素的过渡系数.结果表明,通过焊芯过渡合金元素的高铬合金铸铁堆焊焊条可获得组织和性能均匀的堆焊层.合金过渡系数高于85%.碱性药皮堆焊焊条堆焊层为亚共晶成分高铬合金铸铁,组织由奥氏体γ+马氏体M+碳化物Cr₇C₃组成.堆焊层硬度为44.5~56.5 HRC.碱性石墨化型药皮堆焊焊条堆焊层组织由初生碳化物Cr₇C₃+马氏体M+碳化物Fe₇C₃+少量石墨G组成,堆焊层硬度可达59~67 HRC.

Abstract:

The hardfacing electrodes cored with high chromium casting iron were developed to adequately transfer alloying elements.The transfer coefficient was calculated and the microstructure and hardness of the hardfacing layer from different coatings were investigated.The results indicated that the transfer efficiency of electrodes was more than 85%.Different compositions and microstructure in the hardfacing layer can be obtained using the same-cored wire covered with different coatings.When the cored welding-wire was covered with alkalescent low-hydrogen coating, the hardfacing layer with hypoeutectic high chromium casting iron formed and the microstructure consisted of primary austenite γ, martensite M and carbide.While covered with alkalescent graphite coating, the hardfacing layer with hypereutectic high chromium casting iron was formed and the microstructure consisted of primary carbide, martensite M, carbide Fe₇C₃ and a small amount of G.Since hard Cr₇C₃ and martensite phases existed in the hardfacing layer, the hardness of the hardfacing layer was high.The hardness of the hypoeutectic and hypereutectic high chromium casting iron hardfacing layers was 44.5-56.5 HRC and 59-67 HRC, respectively.