EFFECT OF HEAT INPUT AND POST-WELD HEAT TREATMENT ON THE MECHANICAL AND METALLURGICAL CHARACTERISTICS OF LASER-WELDED MARAGING STEEL JOINTS

Abstract

This paper investigates the impact of heat input and post-weld aging behavior at different temperatures on the laser paper welded maraging steel grade 250. Three different levels of heat inputs were chosen and CO2 laser welding was performed. Aging was done at six different temperatures: 360[Formula: see text]C, 400[Formula: see text]C, 440[Formula: see text]C, 480[Formula: see text]C, 520[Formula: see text]C and 560[Formula: see text]C. The macrostructure and microstructure of the fusion zone were obtained using optical microscope. The microhardness test was performed on the weld zone. Tensile tests and impact tests were carried out for the weld samples and different age-treated weld samples. Fracture surfaces were investigated by scanning electron microscopy (SEM). Microhardness values of the fusion zone increased with increasing aging temperature, while the base metal microhardness value decreased. Tensile properties increased with aging temperature up to 480[Formula: see text]C and reduced for 520[Formula: see text]C and 560[Formula: see text]C. This was mainly due to the formation of reverted austenite beyond 500[Formula: see text]C. XRD analysis confirmed the formation of reverted austenite.