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Test method for researching transformation mechanism of martensite in austenitic stainless steel

A technology of austenitic stainless steel and martensitic transformation, applied in the direction of applying stable tension/pressure to test the strength of materials, etc., can solve the problems of scrapping pressure vessels, user safety risks, economic losses, etc.

Active Publication Date: 2013-01-30
EAST CHINA UNIV OF SCI & TECH
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Problems solved by technology

At this time, the transformation mechanism of martensite under stress and low temperature must be considered. According to the requirements of the allowable stress design of the pressure vessel, different hydraulic levels are used to obtain the required martensite content, so as to achieve the purpose of strengthening the stainless steel vessel. If using Unreasonable stress will lead to explosive transformation of martensite, which will lead to the scrapping of pressure vessels, causing serious economic losses to enterprises, or bringing great safety risks to users

Method used

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  • Test method for researching transformation mechanism of martensite in austenitic stainless steel
  • Test method for researching transformation mechanism of martensite in austenitic stainless steel
  • Test method for researching transformation mechanism of martensite in austenitic stainless steel

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Embodiment 1304

[0026] Stress relaxation test under embodiment 1304 stainless steel liquid nitrogen temperature

[0027] Such as figure 1 As shown, the low temperature stress relaxation test method of the present invention is carried out on the electro-hydraulic servo universal testing machine 1, and the sample 3 is 304 stainless steel, and the specific test steps are as follows:

[0028] I. sample 3 is contained in the cryogenic tank 5, pours liquid nitrogen, thermocouple 2 measures the temperature of the liquid nitrogen in the cryogenic tank 5, and the liquid nitrogen temperature is controlled at -196 ℃;

[0029] II. According to the cross-sectional size of sample 3 (a round bar sample with a diameter of Φ6mm), according to the formula "load = stress × cross-sectional area of ​​the sample", calculate the test stress required for 100MPa, 300MPa, 500MPa, and 700MPa respectively. Load, through the automatic control program of the testing machine 1, load the sample 3 to the required load withi...

Embodiment 2

[0032] Example 2 Creep deformation test of 304 stainless steel at liquid nitrogen temperature

[0033] The test device used in this example, the sample type are identical with embodiment 1, and difference is that test load remains constant in this method, concrete steps are as follows:

[0034] I. sample 3 is contained in the cryogenic tank 5, pours liquid nitrogen, thermocouple 2 measures the temperature of the liquid nitrogen in the cryogenic tank 5, and the liquid nitrogen temperature is controlled at -196 ℃;

[0035] II. According to the cross-sectional size of sample 3 (a round bar sample with a diameter of Φ6mm), according to the formula "load = stress × cross-sectional area of ​​the sample", calculate the load required for the test stress to be 500MPa and 600MPa respectively, and pass the test The automatic control program of machine 1 loads the sample 3 to the required load within 30 seconds and keeps the load constant;

[0036] III. Observe the change of sample defor...

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Abstract

The invention discloses a method for researching the transformation characteristic of martensite in deformation strengthening austenitic stainless steel in a low-temperature environment. The method comprises the following steps of: performing a stress-applied creep test and a constant-strain relaxation test on an austenitic stainless steel material in the low-temperature environment; and acquiring the transformation mechanism of the martensite in the deformation strengthening austenitic stainless steel in the low-temperature environment by a stress relaxation curve and a sample deformation curve. The problem that research on the transformation mechanism of the martensite by applied stress or strain under the condition of sufficient degree of supercooling does not exist in the prior art is solved; and the method is simple and effective and is used for testing the transformation mechanism of the martensite under the condition of stress or strain in the low-temperature environment, provides technical support for manufacture of the austenitic stainless steel for a deformation strengthening pressure vessel in the low-temperature environment, and has quite important value and significance on research of the transformation mechanism of the martensite in the austenitic stainless steel in the low-temperature environment.

Description

technical field [0001] The invention relates to a new test method for testing the martensite transformation mechanism in deformation-strengthened austenitic stainless steel under low-temperature environment, more specifically, a creep test method for studying the martensite transformation mechanism in deformation-strengthened austenitic stainless steel under low-temperature environment. method of transformation mechanism. Background technique [0002] Stainless steel has good corrosion resistance, excellent shape, toughness, weldability and cold workability, and is widely used in pressure vessel equipment (including fixed and mobile pressure vessels, heat exchangers, etc.) in petroleum, chemical, nuclear power and other industrial fields. Wait). However, for example, 304 stainless steel also has disadvantages such as low strength, poor stress corrosion resistance, high sensitivity to intergranular corrosion, and martensitic transformation during cold working, which limits i...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N3/18
Inventor 王琼琦吕雨田涂善东轩福贞庄法坤
Owner EAST CHINA UNIV OF SCI & TECH
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