REHEAT CRACKING IN 2.25CR-MO WELD METAL - INFLUENCE OF RESIDUAL ELEMENTS AND MICROSTRUCTURE

In multipass submerged-arc welds deposited from 2· 25 Cr–Mo wires of controlled difference in purity, the reheat-cracking susceptibility was only slightly dependent on the residual-element content. When the wires were used to deposit tungsten inert gas (TIG) welds, the effect of residual elements remained small, but the extent of grain refinement was significantly increased and the reheat-cracking resistance consequently improved. A TIG weld deliberately made to maximize grain refinement was of very high resistance to reheat cracking even though of relatively low purity. Hence, it is concluded that by appropriate choice of welding process, grain refinement can be maximized in both weld metal and heat-afrected zone, and reheat cracking in low-alloy power-plant steels consequently can be prevented. Special measures to reduce the residual-element content below the levels generally obtained in current low-alloy steelmaking practice, therefore, should be unnecessary. © 1979, The Metals Society. All rights reserved.