Stavax ESR钢洗衣机面板模具开裂原因分析

针对Stavax ESR钢洗衣机面板模具开裂问题,对模具失效件进行断口扫描电镜及微区能谱分析,以及采用金相显微镜对材料基体组织进行检测,综合检测结果,最终确定造成模具早期开裂的内在原因,是由于组织中沿晶界残留未溶颗粒状及薄片状碳化物,材料强度急剧降低,脆性显著增大。模具在热加工过程中碳化物沿晶界析出形成网状碳化物,在热处理加热保温过程中,网状碳化物经过固溶和聚集,形成未溶颗粒状及薄片状碳化物。热处理加热过程的热应力以及淬火过程的组织应力,导致未溶颗粒状及薄片状碳化物周围产生内裂纹。模具冷却水孔的机加工过程,使沿晶开裂特征的内裂纹显露出来。模具服役承载时产生的工作应力,促使裂纹的进一步萌生和扩展。

Analysis on the causes of mold cracking for steel Stavax ESR washing machine

For the cracking in the panel mold of steel Stavax ESR washing machine, the fracture failure in the mold was studied by frac-ture scanning electron microscopy and micro-zone energy spectrum analysis, and the matrix structure was detected by metallographic mi-croscope. The internal cause of mold cracking was residual undissolved granular and flaky carbide along the grain boundary in the organi-zation, the sharp decrease of material strength, and the remarkable increase of brittleness. In the hot-rolling process of mold, mesh car-bide was separated out along the grain boundary, and undissolved granular and flaky carbide were formed by the solid solution and aggre-gation during the heat treatment and heating process. Therefore, the thermal stress of heating process and the microstructural stress of quenching process resulted in internal cracks around the undissolved granular and flaky carbides. Furthermore, the cracks with intergranu-lar cracking characteristics were exposed in the machining process of mold cooling water hole, and the work stress produced by the load of mold promoted a further crack initiation and propagation.