Austenitic heat-resistant alloy

Abstract

An austenitic heat-resistant steel containing, by mass, 0.05-0.16% of C, 0.1-1% of Si, 0.1-2.5% of Mn, 0.01-0.05% of P, less than 0.005% of S, 7-12% of Ni, 16-20% of Cr, 2-4% of Cu, 0.1-0.8% of Mo, 0.1-0.6% of Nb, 0.1-0.6% of Ti, 0.0005-0.005% of B, 0.001-0.15% of N, and 0.005% or less of Mg and / or 0.005% or less of Ca, the amounts of Nb and Ti being 0.3% or above in total, with the remainder being made up by Fe and unavoidable impurities. The cumulative number density of a precipitate has a particle diameter of over 0 nm to 100 nm being 0.1-2.0 / [mu]m2, the precipitate particle diameter corresponding to half of the cumulative number density in the distribution of the cumulative number density and the precipitate particle diameter is 70 nm or less, the average hardness is 160 Hv or less, and the grain size number is 7.5 or above.

Description

technical field [0001] The present invention relates to austenitic heat-resistant steels. Background technique [0002] Usually, energy-related equipment such as boilers and reaction vessels are used in high-temperature processes of hundreds of degrees or more, so heat-resistant materials that have excellent creep strength even in high-temperature environments are required. [0003] For this heat-resistant material, in order to obtain excellent creep strength in a high-temperature environment, there are the following methods: adding elements that can be dissolved in steel in a high-temperature environment to obtain a solid-solution strengthening effect; adding elements that precipitate in a high-temperature environment The method of forming precipitates in high temperature environment to obtain precipitation strengthening effect, the method of coarsening the crystal grains and inhibiting the sliding of grain boundaries, etc. [0004] Among them, in the method of coarsening ...

AI Technical Summary

Problems solved by technology

In order to solid-solve more precipitated components, it is necessary to perform such final heat treatment at as high a temperature as possible, but there is a possibility of coarsening of crystal grains, which may result in a decrease in water vapor oxidation resistance

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