What are the main processing challenges shared by tantalum, niobium and zirconium?

All three refractory metals show intense chemical activity when heated to high temperatures, readily combining with oxygen, nitrogen and carbon to form brittle intermetallic compounds, which sharply reduce ductility and impact toughness. Their high melting points demand special vacuum smelting and vacuum heat treatment equipment, greatly raising production costs. Severe work hardening occurs during cold rolling and drawing, requiring multiple intermediate annealing cycles. Welding must adopt full argon shielding; tiny air leakage will cause brittle cracks on welding seams and reduce component service life.