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Homogenization of martensitic stainless steel after remelting under a layer of slag

A martensitic stainless steel, remelting technology, applied in the field of manufacturing martensitic stainless steel, can solve problems such as large service life dispersion

Active 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

[0008] Although ESR technology can reduce the dispersion in the fatigue characteristics of martensitic stainless steel by removing slag inclusions, the dispersion is still too large in terms of the service life of the component

Method used

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  • Homogenization of martensitic stainless steel after remelting under a layer of slag
  • Homogenization of martensitic stainless steel after remelting under a layer of slag
  • Homogenization of martensitic stainless steel after remelting under a layer of slag

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Embodiment Construction

[0021] During the ESR process, the steel that has been filtered by the slag is cooled and gradually solidified to form a steel ingot. This solidification occurs during cooling and involves the growth of dendrites 10 as shown in FIG. 3 . Consistent with the phase diagram of martensitic stainless steel, the dendrites 10, corresponding to the first solidified grains, are intrinsically richer in α-source elements, while the interdendritic regions 20 are richer in γ-source elements (for the known leverage of the phase diagram application of the rules). The α source element is an element that contributes to a ferritic type structure (a structure that is more stable at low temperatures: bainite, ferritic-pearlite, martensite). The gamma source element is an element that contributes to the austenitic structure (more stable structure at high temperature). Consequently, segregation occurs between the dendrites 10 and the interdendritic regions 20 .

[0022] This localized segregation...

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Abstract

The present invention relates to a method for producing a martensitic stainless steel that includes a step in which an ingot of the steel is remelted under a layer of slag, followed by a step in which the ingot is cooled. Before the skin temperature of the ingot resulting from the slag remelting step drops below the martensitic transformation temperature Ms of the steel, the ingot is placed in a furnace, the initial temperature T0 of which is then above the cooling-induced pearlite transformation finish temperature Ar1 of the steel. In the furnace, the ingot is subjected to a homogenization treatment at least for a holding time t after the temperature of the coolest point in the ingot has reached a homogenization temperature T, said holding time t being equal to at least one hour and the homogenization temperature T varying between approximately 900 DEG C and the burning temperature of the steel.

Description

technical field [0001] The present invention relates to a method of manufacturing martensitic stainless steel comprising the step of electroslag remelting of said ingot, followed by the step of cooling said ingot. [0002] In the present invention, unless otherwise stated, component percentages are weight percentages. Background technique [0003] Martensitic stainless steel is steel with a chromium content of more than 10.5%, and its structure is basically martensitic. [0004] It is important that the fatigue properties of this steel are as good as possible, in order to maximize the service life of components produced from this steel. [0005] For this reason, it is sought to improve the slag inclusion characteristics of steel, ie to reduce the amount of undesired slag inclusions (some alloy, oxide, carbide and intermetallic phases) present in steel. This slag inclusion acts as a crack initiation site, causing premature failure of the steel under cyclic loading. [0006...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D6/00C22B9/18
CPCC21D6/002C22B9/18C21D6/004
Inventor 劳伦特·费勒帕特里克·菲利普森
Owner SN DETUDE & DE CONSTR DE MOTEURS DAVIATION S N E C M A