Preparation method of P110-grade expansion tube for exploiting petroleum and gas

The invention relates to a preparation method of a P110-grade expansion tube for exploiting petroleum and gas. The expansion tube comprises the following chemical components by mass percentage: 0.10-0.30 of C, 0.70-2.0 of Mn, 0.3-1.5 of Si, 0-1.0 of Al, 0.02-0.1 of Nb, 0-0.02 of Ti and the balance of Fe and inevitable impurities. The preparation method comprises the following steps of: after performing smelting and rolling to obtain a related alloy plate, performing plate rolling to the alloy plate and welding to prepare the expansion tube, and finally, performing complete austenitizing and then carrying out heat treatment process of quenching and subsequent subtemperature tempering-quenching-partitioning to enable an expansion tube to reach expected strength criterion and plastic deformation ability and ensure the mechanical property of the tube after and before tube expansion to meet provisions of API (American Petroleum Institute) and other relevant standards. Test results show that the P110 steel grade mu