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Stress-relief annealing method for thermally-demolded CrNi-containing steel ingot

A stress-relief annealing and stress-relief technology, applied in the field of heat treatment, can solve problems such as steel ingot cracks and incomplete annealing of CrNi steel ingots, and achieve the effect of solving crack problems

Active Publication Date: 2017-04-05
INST OF METAL RESEARCH - CHINESE ACAD OF SCI +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] The purpose of the present invention is to provide a method for stress relief annealing of CrNi steel ingots containing thermal demoulding, which solves the technical problem that the ordinary stress relief annealing of CrNi steel ingots is not complete and easily causes cracks in the steel ingots, so that the steel ingots do not produce cracks after stress relief annealing

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] 5 tons of 20CrNi2Mo, the steel ingot was removed from the mold 6 hours after pouring, the surface temperature was 800°C at the head and 600°C at the tail. After ejecting the mold, put it into the furnace for 5 minutes. The initial holding temperature in the furnace is 600°C, and the holding time is 3h. The high-temperature austenitizing holding temperature is 840°C. The holding time is 1h / 100mm+3h. 100mm+3h, then cool to 200°C and air cool. After inspection, the steel ingot has no cracks.

Embodiment 2

[0022] 13 tons of 30Cr2Ni2Mo, the steel ingot was removed from the mold 7 hours after pouring, the surface temperature was 1000°C at the head, and 700°C at the tail. After the mold was removed, it was put into the furnace for 10 minutes. The temperature is 810°C, the holding time is 1h / 100mm+3h, the furnace is cooled to 660°C, the holding time is 1h / 100mm+3h, and then cooled to 200°C and then air-cooled. After inspection, the steel ingot has no cracks.

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Abstract

The invention relates to the field of thermal treatment, in particular to a stress-relief annealing method for thermally-demolded CrNi-containing steel ingot. The stress-relief annealing method comprises the following steps of: firstly, carrying out thermal demolding on CrNi-containing high-hardenability steel ingot, wherein the surface temperature of the demolded steel ingot is not lower than 500 DEG C; and then, carrying out complete stress-relief operation on the demolded steel ingot through an in-furnace initial heat preservation stage, a high-temperature austenization stage and a tissue control stage; carrying out stress-relief operation on the steel ingot through the in-furnace initial heat preservation stage, the high-temperature austenization stage and the tissue control stage, finally cooling the steel ingot to a temperature lower than 200 DEG C and discharging the steel ingot out of the furnace, wherein thermal stress is ensured to be not generated. The stress-relief annealing method solves the technical problem that the steel ingot easily generates cracks due to the fact that common stress-relief annealing for CrNi steel ingot is incomplete, so that cracks are not generated after stress-relief annealing is carried out on the steel ingot.

Description

technical field [0001] The invention relates to the field of heat treatment, in particular to a stress-relief annealing method for a CrNi-containing steel ingot by thermal demoulding. Background technique [0002] CrNi-containing steel ingots often have cracks after annealing. The main root cause is that the stress has not been well eliminated, which has brought huge economic losses to the enterprise. It is generally believed that Ni-containing steel has good toughness and can be annealed at low temperature (less than 650°C), but most of these CrNi steels have good hardenability, the structure is biased towards bainite and martensite, and the structure stress is relatively low. If the ingot is large, cracks will still appear after annealing at this temperature, and even a small ingot of 3 tons will have similar problems. For this reason, a reliable steel ingot stress relief annealing process is required Contents of the invention [0003] The object of the present inventi...

Claims

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Application Information

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IPC IPC(8): C21D1/30C21D6/00
Inventor 傅排先张志成刘光辉陈君刘宏伟吕文俊刘月云李殿中
Owner INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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