Production method of resistance to hydrogen induced cracking steel material

摘要

PURPOSE: To obtain a steel material for hydrogen induced cracking resistance of a line pipe for sour and large heat input welding by restaining free oxygen content before deoxidation of the molten steel to a specific quantity and executing the stirring with inert gas and the standing in the specific times after adding Ca. ;CONSTITUTION: In the reducing method of the steel material for hydrogen induced cracking resistance by molten iron pretreatment, converter refining, ladle refining and continuous casting process, the carbon content at the end point in the molten steel in the converter is controlled so as to become ≤600ppm the free oxygen content before deoxidation This molten steel is deoxidized, and after adding Ca so that Ca/S value in the molten steel becomes suitable, the molten steel is stirred for ≥2 min by the inert gas and successivethe molten steel is stood for ≥30 min in the ladle. By this method, even in the case of being a little desulfurized steel, A series inclusion (MnS) and B series inclusion (Ca-Al sulfated series inclusion cluster) causing to HAZ hydrogen cracking in the large heat input submerged arc welding is remarkably reduced, and the developing ratio of the HAZ cracking is remarkably reduced.;COPYRIGHT: (C)1995,JPO