Abstract: The Fe-Cr-Ni-Mo-Ti(0Cr13Ni7MoTi)stainless maraging steel laser weldments have been investigated after post-weld ageing at different temperatures. The post-weld ageing treatments are performed in a temperature range of 420 ℃ to 580 ℃. Metallographic characterization of laser weldment reveals three zones, i.e. fusion zone, heat affected zone(HAZ) and unaffected parent material zone. Martensite is the predominant phase in the three zones when the ageing temperature is lower than 500 ℃, and large amount of reverted austenite occur in the three zones on ageing at above 540 ℃, this lead to hardness decrease in fusion zone and HAZ. After aging treatments, the hardness in three regions varies in different ways, low hardness appears in the HAZ or unaffected parent material zone. The tensile tests reveal that fracture location occurred in low hardness region and tensile properties are optimum after ageing at 460 ℃. Tensile fracture mechanism changes from brittle fracture to the ductile fracture under given aging treatments conditions.

Key words: Laser beam welding, Maraging steel, Mechanical properties, Microstructure