Structure of near-weld zone of quenched high-carbon steel after welding with rapid cooling

Abstract

Purpose. Study the structure of the heat-affected zone of a welded joint of high-carbon low-alloy steel hardened to martensite after manual arc welding with accelerated cooling.Research methods. Optical and scanning electron microscopy was used to study microstructures. The hardness of the samples was measured using Vickers hardness tester equipped with a computer-controlled positioning and indentation of the sample, as well as determining the diagonals of the prints.Results. Plates of martensite-hardened high-carbon low-alloyed steel and low-carbon steel immersed in water (except edges to be welded) are welded by manual arc welding. The microstructure of the welded joint was investigat­ed. The sizes of characteristic areas of heat-affected zones and the hardness of the material at various distances from the fusion boundary were determined.Scientific novelty. For the first time, high-carbon steel quenched to martensite without tempering was welded with simultaneous accelerated cooling in water. It has been established that in the structure of the heat-affected zone a solid martensitic layer is not adjacent to the fusion boundary, but is separated from it by a layer of austenite.Practical value. The principal possibility of welding heat-treated high-carbon wear-resistant steels without deterioration the structure obtained by preliminary heat treatment is shown.