TA1, TA2, TA3, and TA4 are the four grades of industrial pure titanium defined by the Chinese standard GB/T 3620.1. The letter T stands for titanium, and A indicates the lowest impurity level. As the number increases, the allowable content of interstitial elements (oxygen, nitrogen, carbon, iron) slightly increases, resulting in higher strength but lower ductility. These grades are unalloyed titanium, meaning they contain at least 98.8 to 99.5 percent titanium depending on the grade. The differences in mechanical properties come from controlled variations in oxygen and iron content.

Chemical composition (maximum limits by weight):

● TA1: Fe 0.20%, O 0.18%, C 0.08%, N 0.03%, H 0.015%

● TA2: Fe 0.30%, O 0.25%, C 0.08%, N 0.03%, H 0.015%

● TA3: Fe 0.30%, O 0.35%, C 0.08%, N 0.05%, H 0.015%

● TA4: Fe 0.50%, O 0.40%, C 0.08%, N 0.05%, H 0.015%

Mechanical properties (minimum, typical):

● TA1: Tensile strength 240–370 MPa, yield strength 140–170 MPa, elongation 24–30%

● TA2: Tensile strength 340–440 MPa, yield strength 275–345 MPa, elongation 20–25%

● TA3: Tensile strength 440–540 MPa, yield strength 380–450 MPa, elongation 18–22%

● TA4: Tensile strength 540–640 MPa, yield strength 480–550 MPa, elongation 15–18%

All four grades share excellent corrosion resistance, especially in seawater, chlorides, oxidizing acids, and many chemical environments. They have low density (4.51 g/cm³), high melting point (about 1660°C), good biocompatibility, and non-magnetic properties. However, pure titanium has relatively low hardness and poor wear resistance.

Common standards equivalents:

● TA1 corresponds to ASTM Grade 1 (commercially pure titanium, lowest strength, highest ductility)

● TA2 corresponds to ASTM Grade 2 (standard industrial pure titanium, most widely used)

● TA3 corresponds to ASTM Grade 3 (medium strength)

● TA4 corresponds to ASTM Grade 4 (highest strength among pure titanium grades)

Typical applications:

● TA1: Chemical and marine equipment requiring maximum formability and corrosion resistance, such as heat exchanger tubes, bellows, and thin-wall components.

● TA2: General industrial applications including pressure vessels, piping systems, pump bodies, valve components, and desalination plants. This is the most widely used grade.

● TA3: Slightly higher strength components where moderate forming is still required, such as aerospace brackets and deep-sea housings.

● TA4: Structural parts demanding maximum strength from unalloyed titanium, such as fasteners, springs, and medical implants (though Ti-6Al-4V is more common for high-stress implants).

Selection guidance: For applications requiring extensive cold forming (bending, drawing), TA1 or TA2 are preferred. For general corrosion-resistant equipment, TA2 is the standard choice. When higher strength is needed without adding alloying elements, TA3 or TA4 should be selected, but note that their ductility and weldability are slightly reduced compared to TA1. For most chemical processing and marine applications, TA2 (Grade 2) offers the best balance of strength, ductility, and cost.