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本文探讨了影响断口形貌的几个因素,并提出了使合金棒得到塑性平整断口的工艺。采用不同挤压温度的φ22mm挤压棒材,经过不同制度的热处理后,测试了拉伸、扭转、冲击、剪切等性能,用反极图法测定了合金的织构系数和取向因子,观察了显微组织和宏观断口,并用扫描电子显微镜观察了断口形貌。 研究表明,断口形貌与材料的各向异性、显微组织中的α相形貌和海绵钛的品位有关。当材料的纵向剪切强度和横向的取向因子分别大于或接近于横向剪切强度和纵向取向因子时,则得平断口。反之得劈裂断口。具有块状α加时效β组织状态的棒材易劈裂,而一定数量的块状α加一定数量的针状α加时效β和魏氏组织状态得到平断口。提高海绵钛的品位能提高平断口的几率。 文中提出了得到平断口的工艺,即采用一级海绵钛,在两相区上部进行挤压,对于块状α加时效β的组织,也可以通过双重热处理工艺来改善断口形貌。给出了材料的不同显微组织对应的力学性能及扭转断口形貌。
In this paper, several factors that affect the fracture appearance are discussed, and the technique of making the alloy rod to be plastically cut is proposed. Tensile, torsion, impact and shearing were tested by the different extrusion temperature of φ22mm extruded bar after heat treatment under different regimes. The texture coefficient and orientation factor of the alloy were measured by reverse pole figure method. The microstructure and macroscopic fracture were observed, and the fracture morphology was observed by scanning electron microscope. The results show that the fracture morphology and the material anisotropy, the microstructure of α phase morphology and titanium sponge grade related. When the material’s longitudinal shear strength and transverse orientation factor are greater than or close to the transverse shear strength and longitudinal orientation factor, respectively, then the flat fracture. Instead, splitting fracture. With the block α and β aging state of the body easy to splitting the bar, while a certain number of massive α plus a certain number of acicular α plus β and Wei’s tissue state to be flat fracture. Increase the grade of sponge titanium can improve the probability of flat fracture. In this paper, a flat fracture process is proposed, that is, a first grade titanium sponge is used for extrusion in the upper part of the two-phase zone. The fracture morphology can also be improved by the double heat treatment process for the massive α and β aging microstructure. The mechanical properties of the different microstructures of the material and the torsional fracture morphology are given.