一种新型钛合金半固态锻造后的断裂行为研究

Fracture behavior of a new titanium alloy by semi-solid forging

以新型钛合金Ti14为对象,对比研究常规和半固态锻造合金经不同时间热暴露后的室温拉伸性能,探讨热暴露后的断裂行为及其断裂机制。结果表明,半固态锻造试样热暴露后的强度均明显高于常规锻造试样,而塑性略低于常规锻造试样。常规锻造试样宏观断口三要素清晰可见,断口由细小的韧窝组成,韧窝密度较大;半固态锻造试样纤维区模糊,剪切唇区较大,断口为韧窝和解理的混合型断口,并伴随少量二次裂纹的出现。析出相的尺寸、形态、分布的差异是导致两种锻造态合金热暴露后断裂机制改变的主要原因。

The tensile properties at room temperature of two forging state（conventional forging（CF） and semi-solid forging（SSF）） Ti14 alloy,a new titanium alloy,after thermal exposure for different time were investigated.The fracture behaviors and mechanism of different forging state Ti14 alloy after thermal exposure were analyzed.The results show that Ti14 alloy after SSF has apparently higher tensile strength than that after CF,but the plasticity of SSF is less than that of CF.On the CF fracture,the three elements of the macrofracture are observed clearly,and the microfracture is formed by high density small dimples;While,SSF fracture has obscure fiber zone and bigger shear lip zone.The microfracture is consisted of dimples and cleavages,accompanied by few secondary cracks.The main reason for influencing the fracture behavior of the two forging state Ti14 alloy after thermal exposure is the variation of precipitate sizes,morphology and distribution.