A method for smelting sa-335p92 steel for supercritical boilers

Abstract

The invention discloses a smelting method of steel SA-335P92 for a supercritical boiler. The method comprises the following steps: (1) performing electric-furnace smelting to obtain molten steel with the carbon content of not more than 0.03% by weight and the temperature of not less than 1,600 DEG C; (2) performing ladle refining, namely (2-1) deoxygenating, (2-2) adjusting components, (2-3) adding an alloy solution obtained in the step (2-2) into the molten steel obtained in the step (2-1) for adjusting the components in an LF furnace, wherein the LF furnace in the step (2) adopts an ultrahigh-power graphite electrode; (3) performing vacuum degassing; (4) adjusting the nitrogen content; (5) pouring. According to the smelting method, carbon-containing materials are not adopted to the greatest extent during ladle refining, so that carbon is prevented from entering the molten steel in a refining process; the carbon increment in the ladle refining process is reduced as much as possible, so that the decarbonization and re-refinement operations do not need to be carried out after ladle refining; compared with the prior art, the smelting method has the characteristic that two processes are removed.

Description

technical field [0001] The invention relates to a method for smelting supercritical boiler steel SA-335P92. Background technique [0002] Steel SA-335P92 for ultra-supercritical boilers contains the following elements by weight: carbon 0.07-0.13%; silicon ≤ 0.50%; manganese 0.30-0.60%; phosphorus ≤ 0.020%; sulfur ≤ 0.010%; 0.30-0.60%; Vanadium 0.15-0.25%; Niobium 0.04-0.09%; Nickel≤0.40%; Aluminum≤0.020%; Boron 0.001-0.006%; Tungsten 1.50-2.00%; 0.030-0.070%; the rest is iron and unavoidable impurities. At present, the traditional smelting process of this steel type consists of the following process steps: [0003] Step 1: electric furnace smelting, oxygen blowing decarburization; Step 2: LF refining, adjusting component temperature; Step 3: VOD vacuum oxygen blowing decarburization; Step 4: LF refining again, adjusting composition and temperature; Step 5: VD vacuum degassing ; Step six: adjust the nitrogen content; Step seven: pouring. [0004] Because the steel alloy c...

AI Technical Summary

Problems solved by technology

[0004] Because the steel alloy content is high and the carbon content is very low, vacuum oxygen blowing is required to reduce the carbon content after refining. When the carbon content is reduced, the alloy will inevitably burn partly. After VOD, it needs to go back to LF refining to adjust the composition, twice. LF refining will greatly increase power consumption and alloy consumption, affecting smelting efficiency and production progress, resulting in a substantial increase in smelting costs