Improvement of mechanical properties of stainless maraging steel laser weldments by post-weld ageing treatments

摘要

The response of stainless maraging steel weldments to post-weld ageing treatment has been investigated. Post-weld ageing was performed at five different temperatures, viz., 420 ℃, 460 ℃, 500 ℃, 540 ℃, and 580 ℃. Metallographic characterization of weldment revealed three zones, namely fusion zone, heat-affected zone (HAZ) and unaffected parent metal zone. Hardness and tensile properties were evaluated after ageing at different temperatures. Hardness in HAZ and fusion zone varied with ageing temperature differently from that of the parent metal; it became higher in HAZ and fusion zone than in parent metal zone above 420 ℃. Among the applied ageing treatments, ageing at 460 ℃ achieved the highest tensile strength. A graph was constructed for determination of fracture location and post-weld heat treatment efficiency based on experimental results, using hardness ratio of HAZ to the treated parent material and hardness ratio of HAZ to the as-received parent material.