Titanium alloys can be divided into three categories according to the composition of phases: α alloys, (α+β) alloys and β alloys, which are represented by TA, TC, and TB in China.
① The α alloy contains a certain amount of elements that stabilize the α phase, and the equilibrium state is mainly composed of the α phase. α alloy has small specific gravity, good thermal strength, good weldability and excellent corrosion resistance. The disadvantage is low strength at room temperature, and it is usually used as heat-resistant and corrosion-resistant materials. α alloys can usually be divided into full 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) alloy contains a certain amount of elements that stabilize the α phase and β phase, and the structure of the alloy in the equilibrium state is α phase and β phase. (α+β) alloy has medium strength and can be strengthened by heat treatment, but its welding performance is poor. (α+β) alloys are widely used, and the output of Ti-6Al-4V alloy accounts for more than half of all titanium materials.
③ The β alloy contains a large amount of elements that stabilize the β phase, which can keep all the high temperature β phase at room temperature. β alloys can usually be divided into heat treatable β alloys (metastable β alloys and near metastable β alloys) and thermally stable β alloys. Heat treatable β alloy has excellent plasticity in the quenched state, and the tensile strength can reach 130-140kgf/mm2 through aging treatment. β alloys are usually used as high-strength and high-toughness materials. The disadvantages are large specific gravity, high cost, poor welding performance and difficult cutting process.

National standard grades: TA1, TA2, TA3, TA7, TA9, TA10, TC4, TC4ELI, TC6, TC9, TC10, TC11

American Standard grades: GR1, GR2, GR3, GR5, GR7, GR12

National standard: GB/T2965-2007, GB/T13810, Q/BS5331-91

American Standard：ASTM B348、ASTM F136、ASTM F67、AMS4928
I. Reference standards
1 : GB 228 metal tensile test method
2: GB/T 3620.1 Titanium and titanium alloy grades and chemical composition
3: GB/T3620.2 Titanium and titanium alloy processed products chemical composition and composition allowable deviation
4: GB 4698 sponge titanium, titanium and titanium alloy chemical analysis methods
Second, technical requirements
1: The chemical composition of titanium and titanium alloy bars should comply with GB/T 3620.1, the provisions of the need for repeated testing, the allowable deviation of the chemical composition should comply with the provisions of GB/T 3620.2.
2: The diameter or edge length of the hot-processed bar and its allowable deviation should be in line with the provisions of Table 1.
3: After hot processing by turning (grinding) polished bars and cold-rolled, cold-drawn bars should meet the allowable deviation of the diameter of the provisions of Table II.
4: After hot processing by turning (grinding) polished bars should not be more than half of its size tolerance.
5: Processing state of the bar's indefinite length of 300-6000mm, annealed state of the bar indefinite length of 300-2000mm, fixed length or times the length of the bar should be within the indefinite length. The allowable deviation of the fixed length is +20mm; the multi-length should also take into account the cut of the bar, each cut amount is 5mm.