Microstructure evolution and mechanical properties of TC1 alloy fabricated by plasma arc cold hearth melting during rolling process

Plasma arc cold hearth melting (PAM) is an effective technology to produce high purity titanium alloy ingots which are widely used in aeronautic and astronautic industries. To date, the development of PAM in our country is still at initial stage. It is necessary to investigate the melting parameters of PAM and the following thermal mechanical processing of the ingots fabricated by PAM. In this study, the TC1 alloy ingots casted by PAM were cogged at β transus temperature and then rolled by unidirectional rolling and cross rolling in the α+β phase field. The typical widmanstatten structure of cast- ingots turned to transformed β morphology after cogging at β transus temperature in which the α phases forms in smaller colonies of laths. After the unidirectinal rolling in the α+β phase field, the α colonies were distorted and the α laths re-arranged along the rolling direction, while they had weaker directivity after cross rolling. The sheets rolled by both unidirectional and cross rolling showed typical prismatic texture. After annealing treatment below the β transus temperature, the α phases turned to equiaxial morphology. The ambient yield strength of the sheet in transverse direction was significantly higher than in rolling direction, which could be attributed to the strong prismatic texture introduced by hot rolling process. © Copyright.