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316L奧氏體不銹鋼低溫超飽和滲碳實驗及熱動力學(xué)模擬研究
發(fā)布人：上海艾荔艾金屬材料有限公司www.jshcn.cn
更新時間：2015-09-30
采用 OM、EPMA、XRD 和 IXRD 等手段，研究了低溫超飽和滲碳（low temperature colossal carburization，LTCC）工藝中 CO氣體濃度對 316L 不銹鋼表面滲碳層的微觀組織、C 濃度分布、表面相結(jié)構(gòu)以及殘余應(yīng)力的影響。
奧氏體不銹鋼低溫超飽和滲碳實驗及熱動力學(xué)模擬研究EXPERIMENTAL RESEARCH AND THERMODYNAMIC SIMULATION OF?LOW TEMPERATURE COLOSSAL CARBURIZATION OF AUSTENITIC?STAINLESS STEEL
采用 OM、EPMA、XRD 和 IXRD 等手段，研究了低溫超飽和滲碳（low temperature colossal?carburization，LTCC）工藝中 CO氣體濃度對 316L 不銹鋼表面滲碳層的微觀組織、C 濃度分布、表面相結(jié)構(gòu)以及殘余應(yīng)力的影響?；跓釀恿W(xué)理論建立 LTCC 傳質(zhì)和擴散模型，利用 DICTRA軟件計算了滲碳層的 C 濃度和活度分布，并與實驗結(jié)果進行比較。結(jié)果表明，經(jīng) LTCC工藝處理后的 316L 不銹鋼表面會形成高硬度的 S 相，并產(chǎn)生壓縮殘余應(yīng)力。另外，增加滲碳工藝中 CO 濃度可以顯著提高不銹鋼表面滲碳層中的 C 濃度，進而提高其硬度和壓縮殘余應(yīng)力。在 C 濃度較低時，計算的 C 濃度和活度分布與實驗結(jié)果吻合很好，當(dāng) C 濃度較高時，由于陷阱陣點的減少以及較大壓縮殘余應(yīng)力的作用導(dǎo)致計算結(jié)果偏低。?
Because of excellent corrosion resistance, good toughness and machinability, austenitic?stainless steels are widely used in many industries. In order to improve the corrosion resistance,?the carbon content of austenitic stainless steel is ultra-low results in low surface hardness, poor?wear and fatigue resistance properties which limit its application. Low temperature colossal?carburization (LTCC) is a kind of novel surface strengthening technology of austenitic stainless?steel which can significantly increase the surface hardness, while keeping the original excellent?corrosion resistance because of the absence of the carbides. The wear, fatigue and corrosion?resistance of austenitic stainless steel of low temperature carburized layer have been investigated?in recent years. However, the researches of key technical parameters, especially the carburizing?atmosphere and the alloying element, have been rarely reported for intellectual property protection.?In this work, OM, EPMA, XRD and IXRD are used to investigate the effect of CO concentration?on the microstructure, carbon concentration distribution, phase constitution and residual stress of?the carburized layer on 316L austenitic stainless steel surface. Based on thermodynamic theory, the?model of carbon transfer and diffusion was also built by software DICTRA to calculate the?distribution of carbon concentration and activity of low temperature carburized layer. The results?reveal that S phase is detected on 316L austenitic stainless steel surface treated by LTCC, and the?compressive residual stress is formed at the same time. The increment of CO concentration can?significantly increase the carbon concentration of carburized layer, which improve the hardness?and compressive residual stress. The simulated carbon concentration and activity distributions?were in accordance with the experimental results when the carbon concentration is lower, but when?the carbon concentration is higher, the simulated carbon concentration is lower than experimental?results due to the decrease of trapping sites and high compressive residual stress.