Precipitation and Properties at Elevated Temperature in Austenitic Heat‐Resistant Steels—A Review

Abstract

The austenitic heat‐resistant steels are significant materials used in boilers and nuclear reactors, owing to the excellent creep, fatigue, corrosion resistance, and mechanical properties. The precipitation and properties degenerate with the increasing temperature. It is necessary to clarify the main precipitation and properties under the service situation. Herein, the characteristic of main precipitation and the potential degraded mechanism of creep, fatigue, oxidation resistance, and corrosion resistance at high temperature are briefly reviewed. The main secondary phases under prolonged service environment include MX phase, M23C6 carbide, Z phase, Laves phase, and σ phase. Precipitation scattered uniformly is conductive to strength properties of steel and vice versa. Coarsening precipitation and the decrease of dislocation density are critical reason for the deteriorated mechanical properties at high temperature. The protective oxide films destroyed after exposure to boiler gas lead to failure of materials.

Effect of Mn addition on microstructure and mechanical properties of GX40CrNiSi25-12 austenitic heat resistant steel

“…These hard phases can effectively pin dislocations and hinder dislocation slip, leading to strengthening of the austenitic steels. This is so-called precipitation strengthening [26][27] .…”

Characterization of Dislocation Structure in a Nb-bearing Austenitic Stainless Steel After Low Cycle Fatigue via TEM and EBSD

“…Austenitic stainless steels (ASS) exhibit complex dislocation structures under fatigue, creep, and creep-fatigue interaction condition, which are mainly the cellular structure [1][2][3][4] , channel/wall structure, persistent slip bands 5,6 , vein/labyrinth dislocation structures 7 , ladder structure 8 , planar slip bands 9 , the corduroy structure 10 . There are two main slip modes of dislocation in ASS under plastic deformation known as the cross slip and the planar slip.…”