TWI Industrial Member Report Summary 429/1990
By R Panton-Kent
Industrial interest is increasing in modified 9%Cr1%Mo steel, which has emerged as a candidate material for pressure vessels and steam generators in modern power plant. Work was undertaken to assess composition, hardness and toughness of manual metal arc (MMA) and electron beam (EB) weldments. Particular attention was paid to the effect of varying niobium content on toughness of MMA weld metal.
A series of multipass V-shaped weld pad specimens were produced using commercial and experimental MMA consumables to evaluate variations in composition and hardness. Butt welds were made in 15mm thick material, using MMA consumables designed to produce weld metal Nb contents of 0.02 and 0.09%. An EB weld was made in 40mm steel. Following post-weld heat treatment (PWHT) at 750 and 760°C, Charpy transition curves were determined for MMA weld metal, and crack tip opening displacement (CTOD) was determined for MMA and EB weldments at selected temperatures within the overall range of -40 to 150°C.