How Much Do You Know About Titanium Alloys?

Titanium alloys can be divided into three categories based on phase composition: α alloys, (α+β) alloys, and β alloys, which are respectively represented by TA, TC, and TB in China.

① Alpha alloys contain a certain amount of elements that stabilize the α phase and are mainly composed of the α phase in a balanced state. They are lightweight, have good thermal strength, excellent weldability, and superior corrosion resistance. However, their drawback is low strength at room temperature, and they are typically used as heat-resistant and corrosion-resistant materials. Alpha alloys can generally be divided into all-α alloys (TA7), near-α alloys (Ti-8Al-1Mo-1V), and α alloys with a small amount of compounds (Ti-2.5Cu). ② (α+β) alloys contain elements that stabilize both the α and β phases, and in a balanced state, the alloy's structure consists of both α and β phases. (α+β) alloys have moderate strength and can be heat-treated for strengthening, although their weldability is poor. They are widely used, with the production of Ti-6Al-4V alloys accounting for more than half of all titanium materials.

③ Beta alloys contain a large amount of elements that stabilize the beta phase, retaining all the high-temperature beta phase down to room temperature. Beta alloys are generally divided into heat-treatable beta alloys (sub-stable beta alloys and near-sub-stable beta alloys) and heat-stabilized beta alloys. Heat-treatable beta alloys exhibit excellent plasticity in the quenched state and can achieve tensile strengths of 130 to 140 kgf/mm² through aging treatment. Beta alloys are typically used as high-strength, high-toughness materials. Their drawbacks include high density, high cost, poor welding properties, and difficult machining.