Fine structure in the inter-critical heat-affected zone of HQ130 super-high strength steel

[摘要] The microstructure in the inter-critical heat-affected zone (ICHAZ) of HQ130 steel, has been investigated by thermo-simulation test, SEM and TEM. The problem of toughness decrease in the ICHAZ (ð‘�??_p = 800°C) as well as the effect of Mâ€�?�A constituent and carbide precipitation on brittleness was analysed. The test results indicated that the microstructure in the ICHAZ of HQ130 steel was mostly a mixture of lath martensite (ML) and granular bainite (Bg) with a fine but nonuniform grain structure. The cause of brittleness in the ICHAZ was related to production of the Mâ€�?�A constituent in the local region and carbide precipitation. By controlling the welding heat input carbide precipitation and the formation of the Mâ€�?�A constituent can be avoided or decreased.

[学科分类] 材料工程

[关键词] High strength steel;heat-affected zone;Mâ€�?�A constituent;fine structure.