RU2439190C1 - Steel - Google Patents

Abstract

FIELD: metallurgy. ^ SUBSTANCE: steel contains carbon, chrome, nickel, silica, manganese, copper, sulphur, phosphorus, aluminium, hydrogen, oxygen, cobalt and iron at the following component ratio, wt %: carbon 0.03-0.06, silica 0.10-0.30, manganese 0.30-0.60, chrome 12.00-13.5, nickel 2.8-3.2, copper 0.8-1.3, hydrogen of not more than 3 ppm, oxygen of not more than 60 ppm, aluminium 0.002-0.015, cobalt of not more than 0.05, sulphur of not more than 0.015, phosphorus of not more than 0.015, and iron is the rest. ^ EFFECT: steel has high ductility and impact strength at negative temperatures, which allows increasing operating life tine of the equipment. ^ 2 tbl

Description

The invention relates to the field of metallurgy, in particular to alloy steel, which can be used for the manufacture of parts of atomic and hydroturbine equipment operating at temperatures from minus 30 to 350 ° C.

Known high-strength corrosion-resistant steel of the martensitic class, consisting of the following components, wt.%:

Carbon up to 0.06 Silicon up to 0.04 Manganese 0.30-0.60 Chromium 12.00-13.0 Nickel 2.8-3.2 Copper 0.8-1.1 Sulfur up to 0.025 Phosphorus up to 0.025 Iron rest

The disadvantage of this steel is its low impact strength, in particular in the region of negative temperatures, and therefore, the increased values of the critical temperature of brittleness.

In order to increase the toughness, an economically alloyed corrosion-resistant steel containing carbon, chromium, nickel, silicon, manganese, copper and iron is proposed, characterized in that it additionally contains aluminum, hydrogen, oxygen and cobalt in the following ratio of components, wt.%:

Carbon 0.03-0.06 Silicon 0.10-0.30 Manganese 0.30-0.60 Chromium 12.00-13.5 Nickel 2.8-3.2 Copper 0.8-1.3 Hydrogen no more than 3 ppm Oxygen no more than 60 ppm Aluminum 0.002-0.015 Cobalt no more than 0,05 Sulfur no more than 0.015% Phosphorus no more than 0.015% Iron rest

The proposed steel, in the manufacture of cast and forged products of elements of AEU equipment, has higher ductility and impact strength at negative temperatures, while the critical temperature of brittleness decreases towards negative temperatures. This will increase the service life of the equipment over 30 years. The achieved effect is ensured by increasing the purity of the metal by non-metallic inclusions by introducing aluminum and oxygen within the specified limits (the content of oxides, silicates, aluminosilicates and sulfides is reduced below 2.5 points on the GOST 1778 scale), as well as by eliminating the possibility of flock formation and hydrogen embrittlement when the hydrogen content is within the specified limits.

The chemical compositions of the three heats of the proposed steel and two heats of known steel are given in table. 1. In the table. 2 shows the mechanical properties and impact strength (including at negative temperatures up to -60 ° C) of the proposed steel after the optimal heat treatment: the first normalization is from 950 ° C, the second normalization is from 800 ° C, tempering at 620 ° C .

Claims (1)

Steel containing carbon, chromium, nickel, silicon, manganese, copper, sulfur, phosphorus and iron, characterized in that it additionally contains aluminum, hydrogen, oxygen and cobalt in the following ratio, wt.%:
Carbon 0.03-0.06 Silicon 0.10-0.30 Manganese 0.30-0.60 Chromium 12.00-13.5 Nickel 2.8-3.2 Copper 0.8-1.3 Hydrogen, ppm no more than 3 Oxygen, ppm no more than 60 Aluminum 0.002-0.015 Cobalt no more than 0,05 Sulfur no more than 0.015 Phosphorus no more than 0.015 Iron Rest