Electroslag smelting method for TWZ-2 steel

Abstract

The invention discloses an electroslag smelting method for TWZ-2 steel (which is a steel type with nitrogen content more than 5000 ppm). The TWZ-2 steel is prepared from the following chemical components in mass percent: smaller than or equal to 0.04% of C, smaller than or equal to 1.00% of Si, 16.5-19.5% of Mn, smaller than or equal to 0.030% of P, smaller than or equal to 0.010% of S, 16.00-18.5% of Cr, 0.40-0.80% of Mo, smaller than or equal to 0.60% of Cu, larger than or equal to 0.40% of N, smaller than or equal to 0.005% of B, and the balance of Ni and unavoidable impurities, wherein the electroslag smelting parameters are as follows: in the slay system, CaF2 is 40%, CaO is 30%, and Al2O3 is 30%, the smelting velocity is 0.7 times the diameter of a crystallizer, the packing ratio is 0.45-0.57, and the electrode insertion depth is 20-30 mm. Proved by contrast tests, the TWZ-2 steel prepared by the electroslag smelting method disclosed by the invention is obvious in effect; the magnetic conductivity qualification rate, is increased from 80% to 100%; the yield of the steel is increased by 15-20 percentage points; the produced benefits are remarkable.

Description

technical field [0001] The invention belongs to the field of metallurgy, and in particular relates to a method for electroslag smelting TWZ-2 steel. Background technique [0002] TWZ-2 refers to steels with a nitrogen content exceeding 5000ppm. This type of steel mainly considers the full austenitization of the steel structure in the composition design, and is mainly used in the petroleum drill collar industry. Due to the high nitrogen content in this type of steel, the nitrogen partial pressure in the molten pool will be slightly higher than the nitrogen partial pressure in the air and slag pool when the nitrogen content in the steel is 1600-1650 °C during the electroslag smelting process, which will cause steel The precipitation of nitrogen in the medium leads to the incompatibility of magnetic permeability. Since all TWZ-2 products are delivered in a fixed length of 11.6 meters, the partial magnetic permeability will cause the entire product to be scrapped, which is a hu...

AI Technical Summary

Problems solved by technology

Therefore, by seeking a low-temperature smelting method, the solubility of nitrogen in steel can be increased, the partial pressure of nitrogen can be reduced, and nitrogen partial overflow caused by nitrogen supersaturation can be prevented, resulting in unqualified magnetic permeability.