Method of manufacturing ultralow-temperature steel through low-alloy steel

Abstract

The invention relates to a method of manufacturing ultralow-temperature steel through low-alloy steel, which comprises the steps of: setting the chemical ingredients and mass percents of the low-alloy steel as follows: 0.16-0.18% of C, 0.20-0.38% of Si, 1.6-1.8% of Mn, not larger than 0.02% of Al, not larger than 0.01% of Cu, not larger than 0.025% of S, not larger than 0.025% of P, 0.12-0.24% of Re, not larger than 0.01% of Pb and not larger than 0.01% of Sn; smelting the low-alloy steel to reduce the compounds with low smelting points and brittle substance, and entering the reducing period when the phosphor content of the molten steel is not larger than 0.02%, wherein the decarburization quantity is not lower than 0.5% at the smelting oxidization period, no peroxidation occurs to cause successive recarburization; and generating white slag and desulfurizing at the reducing period of the smelting procedure, and discharging and casting the steel when the sulfur content is smaller than 0.025%. During the smelting process, S and P, especially P of the low-alloy steel is controlled to the minimum margin to reduce the compounds with low smelting points and the brittle substance so as to improve the low-temperature impact power.

Description

technical field [0001] The invention belongs to the technical field of mechanical manufacturing and casting, and relates to a method for producing ultra-low temperature steel by using low alloy steel. Background technique [0002] The types and chemical compositions of common low-temperature steels are: [0003] The chemical composition % of steel ZG16Mn: C: 0.12~0.2, Si: 0.20~0.50, Mn: 1.2~1.6, S≤0.045, P≤0.04; the chemical composition of steel ZG09Mo2V% C: ≤0.12, Si: 0.20~0.50, Mn: 1.4~1.8, R: 0.02~0.03, V: 0.02~0.08, S≤0.04, P≤0.04; steel grade ZG06MnNb chemical composition % C:≤0.07, Si0.17~0.37, Mn: 1.6~1.8, Nb : 0.03~0.04, V: 0.02~0.08, S≤0.03, P≤0.03; steel grade ZG06AlNbCuN chemical composition % C: ≤0.08, Si≤0.35, Mn: 0.8~1.28, Al0.04~0.15, Cu0.3~ 0.4, N0.01-0.015, Nb0.04-0.08, S≤0.035, P≤0.02. [0004] At present, the properties of low-temperature cast low-alloy steel in my country are: [0005] The steel type ZG16Mn heat treatment specification is 900°C normal...

AI Technical Summary

Problems solved by technology

When the minimum operating temperature is -175°C, instead of using high-alloy steel, the modified ZG16Mn is used instead of high-alloy steel, which cannot meet the low-temperature impact energy requirements.