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Degassing of martensitic stainless steel before remelting beneath a layer of slag

A martensitic stainless steel and electroslag remelting technology, which is used in the field of manufacturing martensitic stainless steel and can solve problems such as fatigue fracture

Inactive Publication Date: 2012-07-11
SN DETUDE & DE CONSTR DE MOTEURS DAVIATION S N E C M A
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0010] Thus, the dispersion results of the fatigue properties, especially at the lower end of the range of results, are due to another unexpected mechanism of premature crack opening of the steel, leading to premature fatigue fracture

Method used

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  • Degassing of martensitic stainless steel before remelting beneath a layer of slag
  • Degassing of martensitic stainless steel before remelting beneath a layer of slag
  • Degassing of martensitic stainless steel before remelting beneath a layer of slag

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Embodiment Construction

[0019] During the electroslag remelting (ESR) process, slag-filtered steel cools and gradually solidifies to form a steel ingot. This solidification occurs during cooling and causes the growth of dendrites, such as image 3 shown. According to the martensitic stainless steel phase diagram, the dendrites 10 corresponding to the first solidified grains are intrinsically richer in the α-cell, while the interdendritic regions 20 are richer in the γ-cell (applying the known levers of the phase diagram rules). The alpha unit cell is a unit cell that favors a ferritic-like structure (a structure that is more stable at low temperatures: bainite, ferritic-pearlite, martensite). The gamma unit cell is a unit cell that favors an austenitic structure (a structure that is stable at high temperatures). For this reason, segregation occurs between the dendrites 10 and the interdendritic regions 20 .

[0020] There is then localized condensation of this chemical composition throughout the ...

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Abstract

The invention relates to a method for producing a martensitic stainless steel, including a step of remelting an ingot of said steel beneath a layer of slag, followed by a step of cooling said ingot. Before the step of remelting beneath a layer of slag, the ingot undergoes a vacuum degassing operation for a sufficient amount of time to obtain a hydrogen content in the ingot of less than 3 ppm.

Description

technical field [0001] The present invention relates to a method of manufacturing martensitic stainless steel, comprising the step of electroslag remelting of said steel ingot and the step of cooling said steel ingot. Background technique [0002] In the present invention, unless otherwise stated, the proportions of ingredients are percentages by weight. [0003] Martensitic stainless steel is a steel with a chromium content of more than 10.5% and a structure mainly martensitic. [0004] It is important that the fatigue properties of this steel are as good as possible so that the service life of components made of this steel is maximized. [0005] For this reason, attempts have been made to improve the impurity characteristics of the steel, ie to reduce the amount of undesired impurities (certain alloys, oxides, carbides, and intermetallic phases) present in the steel. Such impurities can act as crack initiation sites, ie, cause premature failure of the steel under cyclic ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21C7/10C22B9/18
CPCC21C7/10C22B9/18
Inventor 劳伦特·费勒帕特里克·飞利浦森
Owner SN DETUDE & DE CONSTR DE MOTEURS DAVIATION S N E C M A