Electropulsing anisotropy of cold-rolled Grade 2 titanium sheet: Effect of electric current direction on recrystallization and hardness

Abstract

This study investigated the effects of electropulsing treatment (EPT) condition on the microstructure and microhardness of cold-rolled Grade 2 Ti sheet. Particular attention was paid to the dependence of the material properties on the electric current direction, referred to as electropulsing anisotropy. Direct-current (DC) EPT was applied along either the rolling direction (RD) or transverse direction (TD) of the rolled sheet. EPT along the TD resulted in a higher heating rate and maximum temperature, whereas that along the RD accelerated the static recrystallization (SRX) process under identical electropulsing parameters. Such a discrepancy was interpreted using the elongated grain structure and basal texture in the cold-rolled Ti sheet. These results were further supported by microhardness measurements, confirming the presence of electropulsing anisotropy during DC EPT in Ti alloys for the first time. In addition, the employed EPT was compared to a traditional furnace heat treatment (FHT) with rigorous temperature and time control, wherein the optimum EPT process spent only 13% of the processing time to complete SRX with a lower thermal energy requirement. This indicates a significant athermal contribution of EPT to electropulsing anisotropy.

Keywords

• Electropulsing treatment
• Titanium
• Recrystallization
• Hardness
• Anisotropy