Austenitic heat-resistant alloy and method for manufacturing same

Abstract

Provided is an austenitic heat-resistant alloy having high creep strength and high toughness even in a high-temperature environment. This austenitic heat-resistant alloy has a chemical composition containing, in terms of mass%, 0.03 to less than 0.25% C, 0.01-2.0% Si, 2.0% or less of Mn, 10 to less than 30% Cr, more than 25% to 45% Ni, more than 2.5% to less than 4.5% Al, 0.2-3.5% Nb, and 0.025% or less of N, the remainder comprising Fe and unavoidable impurities, and P and S being 0.04% or less and 0.01% or less, respectively, of the impurities. The gross moment of precipitates 6 [mu]m or larger in the structure of the austenitic heat-resistant alloy is 5% or less.

Description

technical field [0001] The present invention relates to a heat-resistant alloy and a manufacturing method thereof, and more specifically, to an austenitic heat-resistant alloy and a manufacturing method thereof. Background technique [0002] In the past, 18-8 stainless steel was used as heat-resistant steel in equipment such as boilers and chemical equipment used in high-temperature environments. 18-8 stainless steel is an austenitic stainless steel containing about 18% of Cr and about 8% of Ni, such as SUS304H, SUS316H, SUS321H, and SUS347H in JIS standards. [0003] In recent years, the service conditions of equipment in high temperature environments have become significantly more stringent, requiring higher creep strength than 18-8 stainless steel. Recently, advanced ultra-supercritical pressure power generation plans are being promoted in thermal power generation boilers that raise the steam temperature from the conventional level of around 600°C to over 700°C. In addi...

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Problems solved by technology

However, the alloy raw materials of these heat-resistant alloys are expensive

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