WELDABILITY OF 21-4-N NITRONIC STEEL

Abstract

This study demonstrate the shielded metal arc weldability of the 21-4-N Nitronic tJ a0.41. steel having the composition — Cr = 21.0%, Ni = 4%, C = 0.08%,,Mn = 8-10%, Si 1.00 max, P=0.060 max, S = 0.06 max., using E 309 Mo (austenitic grade) electrode (4)4,0 mm) of composition Cr = 22-25, Ni = 12-14, Mn = 1.5-2.5, C = 0.06, Mo = 2-3, Si = 1.0. Welding has been carried out under (1) As received condition (2) Solution Annealed condition and PWHT at 300°C and 600°C for Y2 hr. Mechanical properties such as tensile, impact. and hardness of the steel has been studied under as received and solution Annealed condition. Extensive optical metallographic study of base metal, weld metal and heat affected zone in all the cases has been done in the welded conditions and after PWHT at 300°C and 600°C ('/z hr.). SEM analysis of the fracture surfaces ., ., all the cases at room temperature has been done. The mechanical properties such as tensile, impact and hardness of the weldment are comparable to conventional austenitic stainless steel, with improved high temperature strength. Mechanical properties are found to be affected by the microstructure under different welding conditions and PWHT