Production method of L80-1 steel-grade oil casings with low cost

The invention relates to a production method of L80-1 steel-grade oil casings with low cost. The production method is characterized in that chemical components of blanks include, by weight, 0.22-0.32% of C, 0.20-0.35% of Si, 1.30-1.50% of Mn, P smaller than or equal to 0.020%, S smaller than or equal to 0.015%, 0.15-0.30% of Cr and 0.01-0.04% of Al; the production process of the oil casings includes molten iron pretreatment, combined blown converter steelmaking process, LF(ladle furnace) refining, VD (vacuum degasser) vacuum treatment, round continuous casting, blank heating, piercing, continuous rolling, sizing/strength reducing, cooling, sawing, straightening, thermal treatment and flaw detection; the thermal treatment includes preserving heat and water quenching at the temperature of 870 DEG C +/-20 DEG C for 40 minutes, and cooling in air after tempering at the temperature of 690 DEG C+/-20 DEG C and preserving heat for 70 minutes. The production method has the advantages that since the 34MnCr22 steel grade is utilized, material components are reasonable in design, precious metal elements such as Molybdenum are not contained in materials of the casings, and cost is low; in the thermal treatment, water quenching and tempering are utilized, no affection to environment is caused by water quenching, cost is lowered, plasticity of steel is improved greatly on the premise of guaranteeing strength, and impact ductility of steel casings is improved, and thus, the oil casings can meet requirements of API Spec 5CT standards.