本文關(guān)鍵詞： 304奧氏體不銹鋼 應(yīng)變誘發(fā)馬氏體相變 非線性超聲技術(shù)　出處：《華東理工大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：奧氏體應(yīng)變強化技術(shù)廣泛應(yīng)用于核電站、化工廠等處壓力容器的制造,利用這一手段可以有效提高材料強度,從而實現(xiàn)安全生產(chǎn)、節(jié)約原料、降低能耗等目的。而304奧氏體不銹鋼又是工業(yè)領(lǐng)域應(yīng)用較廣的材料,其應(yīng)變強化是通過位錯強化及應(yīng)變誘發(fā)馬氏體相變(DIMT)等微觀結(jié)構(gòu)強化共同實現(xiàn)的。因此,了解形變過程中材料微觀結(jié)構(gòu)變化情況對于了解材料機械性能十分關(guān)鍵,而針對微觀結(jié)構(gòu)變化的檢測手段也就顯得尤為重要。近年來的研究表明,非線性超聲波檢測技術(shù)能夠表征材料變化,且作為一種無損檢測技術(shù)值得研究與探討。本文為了探究非線性超聲波對應(yīng)變過程中不同微觀結(jié)構(gòu)材料的響應(yīng)情況,設(shè)計-70℃、25℃、300℃三種溫度下的單向中斷拉伸實驗,得到含有不同馬氏體相變量的試樣,并對其進行各項超聲波檢測。實驗結(jié)果表明,超聲非線性參數(shù)在三種溫度下均隨形變量的增大而增大,且溫度越低,非線性參數(shù)的增長率越高。通過透射電鏡、電子背散射衍射等微觀分析方法,對304奧氏體不銹鋼形變過程中微觀結(jié)構(gòu)演化情況進行了細致分析,包括位錯增長、位錯胞的形成、層錯和孿晶的產(chǎn)生、剪切帶的發(fā)展以及馬氏體相變的形核與生長過程。觀察后可以確認,低溫下試樣中應(yīng)變誘發(fā)馬氏體相變過程的加快是導(dǎo)致非線性參數(shù)的增長率增加的重要原因。通過對α’-馬氏體含量的檢測,發(fā)現(xiàn)α’-馬氏體的含量隨形變量的增大而增加。通過擬合得到了α’-馬氏體與非線性參數(shù)間的冪函數(shù)關(guān)系式,了解了馬氏體相對超聲非線性檢測的影響。
[Abstract]:Strain strengthening technology is widely used in nuclear power plants, chemical plants and other manufacturing pressure container, use this method can effectively improve the strength of the material, so as to realize safe production, save raw materials, reduce energy consumption. And 304 austenitic stainless steel is widely used in industrial field materials, the strain hardening by dislocation and strain induced martensite (DIMT) microstructure strengthening achieve together. Therefore, understanding the microstructure during deformation of the material changes to understand the mechanical properties of materials is the key, and the detection means for the microstructure change is particularly important. Recent studies show that the nonlinear ultrasonic detection technique can characterize changes and, as a kind of nondestructive testing technology is researched and discussed. In order to explore different nonlinear ultrasonic strain in the process of micro structure of materials The response of the material, the design of -70 C, 25 C, 300 C three one-way interrupt tensile test temperature, containing samples with different martensite phase variables, and the detection of the ultrasonic. The experimental results show that the nonlinear ultrasonic parameters at three different temperatures increased with increasing deformation increases, and the lower the temperature, the higher the growth rate of nonlinear parameters. Through transmission electron microscopy, electron backscatter diffraction analysis method, the microstructure evolution of 304 austenitic stainless steel in deformation is analyzed in detail, including dislocation growth, the formation of dislocation cell, stacking faults and twins, as well as the development of martensitic shear zone phase nucleation and growth process. After the observation can be confirmed, speeding up the transformation process of strain induced martensite under low temperature in the sample is an important cause of nonlinear parameters increase the growth rate. The alpha '- martensite It is found that the content of alpha - martensite increases with the increase of the shape variables. The power function relation between the alpha - martensite and the nonlinear parameters is obtained through fitting, and the influence of martensite on ultrasonic nonlinearity is also known.

【學(xué)位授予單位】：華東理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TG142.71

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2 ;Load Bearing Capacity and Safety Analysis for Strain-hardening Austenitic Stainless Steel Pressure Vessels[J];Chinese Journal of Mechanical Engineering;2011年02期

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本文編號：1447111