Heat-resistant austenitic alloy, heat-resistant pressure-resistant member comprising the alloy, and process for producing the same

Abstract

A heat-resistant austenitic alloy which contains 0.02-0.15%, excluding 0.02%, C, up to 2% Si, up to 3% Mn, up to 0.03% P, up to 0.01% S, 28-38% Cr, 40-60%, excluding 40%, Ni, up to 20% (including 0%) Co, 3-15%, excluding 3%, W, 0.05-1.0% Ti, 0.005-0.2% Zr, and 0.01-0.3% Al and has a N content up to 0.02% and a Mo content less than 0.5%, with the remainder being iron and impurities, and which satisfies relationships (1) to (3). The alloy has a high creep rupture strength, has satisfactory toughness even when used at a high temperature over long, and has excellent hot workability. This heat-resistant austenitic alloy may contain a specific amount of one or more elements selected from Nb, V, Hf, B, Mg, Ca, Y, La, Ce, Nd, Sc, Ta, Re, Ir, Pd, Pt, and Ag. P<=3 / {200(Ti+8.5Zr)} (1) 1.35Cr<=Ni+Co<=1.85Cr (2) Al>=1.5Zr (3).

Description

technical field [0001] The present invention relates to an austenitic heat-resistant alloy which has very high high-temperature strength compared with conventional heat-resistant alloys and which has excellent toughness after long-term use and excellent hot workability, and a heat-resistant alloy composed of the alloy. Pressure-resistant member and method of manufacturing the same. Specifically, it relates to high-temperature strength, particularly creep rupture strength, used as pipes, heat-resistant and pressure-resistant plates, rods, forgings, and the like in power generation boilers, chemical industrial plants, and the like. It is excellent and has excellent toughness after long-term use due to its high structural stability, and has significantly improved hot workability, especially high-temperature ductility at 1150°C or higher, containing 28 to 38% by mass of Cr. The invention relates to a heat-resisting alloy of the alloy system, a heat-resistant and pressure-resistan...

AI Technical Summary

Problems solved by technology

This is because when using materials with poor hot workability to manufacture seamless steel pipes, hot extrusion is often used to make pipes, but if the hot workability under high temperature conditions above 1150°C is insufficient, the internal temperature of the material will be caused by processing heat. Higher than the heating temperature, so defects such as lamination and fracture flaws occur

In addition, if the hot workability under high temperature conditions of 1150° C. or higher is insufficient, the above-mentioned defects will also occur in the piercing process using a piercing mill such as the Mannesmann mandrel mill method.

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