Effect of Heat Treatment on Mechanical Properties of Heavily Cold Rolled Pure Titanium

Abstract

Stainless steel is known as material with high corrosion resistance, and has excellent mechanical properties, workability, heat resistance. Therefore, it is used in a very wide range of fields such as mechanical parts, building materials, chemical parts, aviation parts, medical equipment, and food supplies. On the other hand, along with stainless steel, pure titanium is also known as material showing extremely high corrosion resistance. It has been used for a long time together with titanium alloys as chemical plant and heat exchanger. Pure titanium, which is widely used as a product, is JIS2 type. However, the problem is that the strength of pure titanium is lower than that of titanium alloys. Therefore, it is expected to use pure titanium having high strength while maintaining purity. Generally, cold working and heat treatment methods are used to increase strength. In the present study, the material properties of pure titanium were improved by a combination of cold rolling and heat treatment. Mechanical properties were examined by tensile testing. The test material was a commercially available pure titanium JIS2 sheet. The thickness of the tensile test workpiece was 0.4 to 0.7 mm. The rolling reduction ranged from 75 to 93 %. An increase in tensile strength was obtained in the heat treatment from 400 to 500 oC while maintaining the ductility. Tensile strength was greatly improved under the condition of 93 % of rolling reduction and heat treatment temperature of 400 oC.