TC4钛合金棒材缺陷分析

Defect Analysis of TC4 Titanium Alloy Bar

TC4棒在改锻时,超声波检验发现超限缺陷波。用金相显微镜观察了缺陷处微观组织形貌,用能谱仪测试了缺陷部位成分。结果表明:缺陷区Al、V含量尤其是V含量偏低,富氧含碳和少量的氮,组织为粗大的α相。由此得出缺陷区是冶金缺陷,是氧化的海绵钛熔化形成的富氧夹杂和低密度偏析。为了防止此类缺陷给材料带来危害,生产厂在熔炼时应挑选海绵钛,除去氧化硬块。

Transfinite defect wave were found during ultrasonic inspection process of TC4 forging bar. The microstructure was observed by optical microscope and the chemical composition was evaluated with EDS. The EDS result shows that low Al and V but high O level at the defect area. The V element is lower than the others and there are small amounts of C and N. Additionally, Bulkyα-phase was found in the optical structure. Thus, there should be metallurgical defects which formed by oxidation of titanium sponge during melting process. The formation of defects attribute to oxygen-enriched inclusion and low density segregation. In order to prevent the harmful effects, raw titanium sponge should be chosen to remove oxygen-enriched blocks before smelting.