ASTM A312 TP321H Solid Fin Tube Key Features and Principles Material Composition: TP321H is a modified version of TP321, with a higher carbon content (C: 0.040.10) for improved high-temperature performance. It is stabilized with titanium (Ti: =4C0.60), which enhances its resistance to intergranular corrosion. Mechanical Properties: This grade offers excellent mechanical strength at both high and low temperatures. Typical required mechanical properties include: Tensile