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Precipitation strengthening heat treatment process of austenitic heat-resistant steel containing Nb

A technology of austenitic heat-resistant steel and precipitation strengthening, which is applied in the direction of improving process efficiency, etc., can solve the problems affecting the high-temperature performance of heat-resistant steel, the number of precipitation, and the substructure, so as to meet the performance requirements and avoid brittle cracking , the effect of promoting nucleation

Active Publication Date: 2020-09-25
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Problems solved by technology

Although the formation of Nb(C,N) is beneficial to improve the comprehensive performance of austenitic steel, there are few substructures in the matrix structure of austenitic steel, which cannot provide enough sites for the nucleation of precipitated phases, resulting in the precipitation of Nb(C,N) Less in quantity
During the service of heat-resistant steel, the coarsening rate of Nb(C,N) precipitates with low number density is accelerated, and the strengthening effect is poor, which affects the high-temperature performance of heat-resistant steel

Method used

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  • Precipitation strengthening heat treatment process of austenitic heat-resistant steel containing Nb
  • Precipitation strengthening heat treatment process of austenitic heat-resistant steel containing Nb

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Embodiment 1

[0030] A kind of Nb-containing austenitic heat-resistant steel, composed of the following components in terms of mass percentage:

[0031] C 0.06%, Cr 25.5%, Ni 21.3%, Si 0.9%, Mn 1.4%, N 0.19%, Nb 0.5%, Al 0.002%, Ti 0.001%, Fe balance.

[0032] The Nb-containing austenitic heat-resistant steel of this embodiment is processed through the following processes:

[0033] (1) According to the composition of the Nb-containing austenitic heat-resistant steel in this embodiment, it is smelted into an ingot that meets the requirements by means of vacuum induction melting;

[0034] (2) Heat the ingot at 1300°C for 2 hours for high-temperature solid solution to ensure complete dissolution of primary carbides in the structure and eliminate dendrite segregation in the steel ingot;

[0035] (3) In order to ensure the compactness and uniformity of the structure, the steel ingot obtained in step (2) was furnace-cooled to 1200°C and forged. The initial forging temperature was 1200°C and the ...

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Abstract

The invention discloses a precipitation strengthening heat treatment process for austenitic heat-resistant steel containing Nb. The precipitation strengthening heat treatment process includes the steps that heat preservation is carried out at 1,200-1,300 DEG C for 1-6 hours for carrying out the first time of solution heat treatment, then cooling is carried out until the temperature reaches to 400-700 DEG C at a temperature drop rate of 5-20 DEG C / min for carrying out non-isothermal aging heat treatment, then the temperature is raised up to 950-1100 DEG C and heat preservation is carried out for 0.5-2h for carrying out secondary time of solution heat treatment, and finally water-cooling is carried out to room temperature. Two times of solution heat treatment processes are adopted and combined with non-isothermal aging strengthening heat treatment, the high temperature strengthening effect is good, the precipitation of high-density fine dispersed MX phase is ensured, and the formation ofgrain boundary M23C6 phase and the brittle cracking caused thereby are avoided, so that the strength of the austenitic heat-resistant steel is significantly improved.

Description

technical field [0001] The invention relates to a heat treatment process for alloy steel in the metallurgical industry, in particular to a precipitation strengthening heat treatment process for Nb-containing austenitic heat-resistant steel. Background technique [0002] With the continuous growth of my country's energy demand and structural optimization, ultra-supercritical technology, as a new type of advanced power generation technology with high efficiency and low emissions, will be widely used. Austenitic heat-resistant stainless steel has excellent high-temperature oxidation resistance and good creep resistance, and can be used as an important choice for ultra-supercritical unit structural materials, and is used in pressure-bearing structural parts such as boiler tubes, superheater and reheater pipes . However, with the further development of ultra-supercritical unit parameters, the service creep strength of austenitic heat-resistant steel materials for key large compo...

Claims

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Application Information

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IPC IPC(8): C21D6/00
CPCC21D6/004C21D6/005C21D6/008C21D2211/001Y02P10/20
Inventor 胡国栋郑江鹏李相伟初铭强杨海波张书彦
Owner CENT OF EXCELLENCE FOR ADVANCED MATERIALS
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