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Martensitic stainless steel cementation method and product thereof

A martensitic stainless steel and carburizing technology, applied in coating, metal material coating process, solid-state diffusion coating, etc., can solve the problem of difficulty in ensuring the safety of aircraft, and achieve the effect of improving safety

Active Publication Date: 2008-03-12
SICHUAN LINGFENG AVIATION HYDRAULIC MACHINERY
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  • Abstract
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  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, in some special occasions, such as the flat valve assembly of an aircraft, there are several parts in the assembly that need to be made of martensitic stainless steel and then carburized to meet the requirements of use, otherwise, the safety of the aircraft is difficult to guarantee

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  • Martensitic stainless steel cementation method and product thereof

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Embodiment Construction

[0025] Now take the carburizing heat treatment of 1Cr11Ni2W2MoVA martensitic stainless steel as an example to describe the present invention in detail.

[0026] The martensitic stainless steel material is roughly machined into semi-finished parts, leaving a finishing allowance. Then follow the steps shown in Figure 1 for processing:

[0027] 1. Surface pretreatment

[0028] Sandblast the surface of the semi-finished part to remove oil and destroy the passivation film on the part surface; if necessary, wash the part with 10% phosphoric acid by volume to further corrode the residual passivation film and completely remove it. The chemical reaction is as follows:

[0029] 8H 3 PO 4 +3Fe 3 o 4 →6Fe(PO 4 )+Fe 3 (PO 4 ) 2 +12H 2 o

[0030] h 3 PO 4 +Fe→Fe 3 (PO 4 ) 2 +H 2 ↑

[0031] 3H 2 +Cr 2 o 3 →2Cr+3H 2 o

[0032] The removal of the surface passivation film must be thorough, otherwise it will seriously affect the subsequent carburization. The passivation fi...

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Abstract

The invention discloses a carburizing method for martensite stainless steel containing 10-19% by weight chromium, and a heat treatment method for the product after carburization. Carburization is carried out under 95-1000 DEG C in a methylbenzene atmosphere, pre treatment is carried out before carburization, oily dirt and passivation film is removed. The heat treatment procedures after the carburization are: 1. normalizing; 2. high temperature annealing; 3. tempering in vacuum under 950-1000 DEG C; 4. cold treating; 5. low-temperature annealing, then passivating 5 minutes in a passivating liquid of the following formula: 20-25% (volume) nitric acid and 3-4% (by weight) sodium dichromate. The technical indexes of the product: depth of carburized layer: 0.7-1.0 mm; surface hardness of the carburized layer: HRC>=55; surface hardness of the non-carburized layer: HRC33-45; metallographic structure: the class of carbide in the carburized layer, the residual austenite and central structure of the carburized layer are acceptable per HB5492-91; and the high-temperature annealed hardness: HRC<=30.

Description

technical field [0001] The invention relates to a method for carburizing the surface of a metal body, specifically, a method for carburizing martensitic stainless steel and its product, and a heat treatment method for the product after carburizing. Background technique [0002] Carburizing and hardening the surface of stainless steel products not only maintains the corrosion resistance of the product, but also improves the wear resistance of the product, and is widely used in the field of machinery manufacturing. [0003] At present, there are many reports on the carburizing process of austenitic stainless steel and austenitic-ferritic stainless steel, such as the "carburizing method of austenitic metal and austenitic metal product made therefrom" published by the Chinese patent ( Application No.: 97101054.4), "High Concentration Carburizing Method for Low Carbon High Chromium Steel" (Application No.: 89104102.8), etc., but there is no precedent for the carburizing process o...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23C8/22C22C38/18C23F17/00C21D1/18C21D1/28C23C22/24
Inventor 郑雄樊佰联彭涛邓忠
Owner SICHUAN LINGFENG AVIATION HYDRAULIC MACHINERY
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