Introduction
Since titanium and titanium alloys have been used in different industries, GB 2965-87 is a standard prescribed by China’s National Standard Committee to define the technical requirements of titanium and titanium alloy bars and other related materials. This paper will introduce and discuss the general requirements, chemical composition, mechanical properties, and some other requirements of titanium and titanium alloy bars according to this standard.
General Requirements
First of all, titanium and titanium alloy bars manufactured according to the standard must be cylindrical bars with a certain length, width and thickness. They should also be free from any defects such as cracks, welds, pits, and other imperfections. Moreover, the surface of the titanium and titanium alloy bars should be smooth and free from oil and other stains.
Chemical Composition
According to GB 2965-87, the chemical composition of titanium and titanium alloy bars should be determined in accordance with the provisions in GB/T 908-2008 or the relevant specification or contract. Generally, the titanium and titanium alloy bars should contain no more than 0.3% aluminum, 0.3% carbon, 0.3% iron, 0.25% oxygen, 0.15% nitrogen, 0.2% hydrogen, 0.02% silicon, 0.002% phosphorous, and 0.001% sulfur.
Mechanical Properties
The minimum mechanical properties of titanium and titanium alloy bars must be in accordance with the relevant specification or contract. For example, the tensile strength, yield strength, and elongation at fracture of titanium and titanium alloy bars should meet the requirements specified by the relevant standard of China. Generally speaking, the tensile strength of titanium and titanium alloy bars should be no less than 372 MPa, the yield strength should be no less than 294 MPa, and the elongation at fracture should be no less than 27%.
Other Requirements
Some other requirements of titanium and titanium alloy bars should also be considered when manufacturing these materials. For example, the diameter tolerance of round titanium and titanium alloy bars should be within +0.5 mm/-0 mm, while the dimensional tolerance of rectangle titanium and titanium alloy bars should be within +0.5 mm/-0 mm. And the roughness of their surface should be no more than 0.6 µm. The electrochemical performance of titanium and titanium alloy bars should also meet the requirements in GB/T 2975-1998.
Conclusion
This paper has introduced and discussed the general requirements, chemical composition, mechanical properties, and some other requirements of titanium and titanium alloy bars according to the national standard GB 2965-87. It should be noted that the titanium and titanium alloy bars should meet the above-mentioned requirements in order to ensure the quality and safety of the finished products.
