兩相區(qū)位錯增殖對Mn元素配分及低碳鋼貝氏體組織影響

兩相區(qū)位錯增殖對Mn元素配分及低碳鋼貝氏體組織影響The Effect of Intercritical Dislocation Multiplication to Mn Partitioning and Microstructure Evolution of Bainite in Low Carbon Steel

采用兩相區(qū)保溫-形變-淬火（DIQ）的熱處理工藝，研究低碳鋼兩相區(qū)形變位錯增殖作用下Mn元素配分行為及其對貝氏體組織的影響規(guī)律。通過金相顯微鏡（OM）、掃描電鏡（SEM）、透射電鏡（TEM）、電子探針（EPMA）和X射線衍射儀（XRD）對組織成分、位錯密度、合金元素分布等進行表征。結(jié)果表明：形變后的鐵素體晶粒和馬氏體板條細化、塊狀馬氏體數(shù)量減少；位錯密度由0.3624×1014 m-2增加至1.1988×1014 m-2，位錯滑移的相互運動提高了空位濃度及間隙溶質(zhì)原子數(shù)量，加速了C、Mn元素在α相與γ相中的擴散速度，促進了Mn元素在兩相區(qū)的配分效果，C、Mn元素富集量及富集區(qū)域增多。采用兩相區(qū)保溫-形變-奧氏體化-淬火-貝氏體區(qū)保溫-淬火（DI&Q&PB）熱處理工藝，殘余奧氏體的量由11.5%提高到13.9%，殘余奧氏體中的碳含量由1.14%提高到1.28%。

The volume fraction and stabilization of retained austenite at room temperature were determined by the degree of stable element partitioning of austenite. The element diffusion behaviors usually had a close relationship with crystal defects, dislocation proliferation caused by high temperature deformation might also increase the vacancy concentration, which contributed to the diffusion of substitutional atoms and interstitial atoms. By adopting a new treatment process of intercritical deformation - hold - quenching (DIQ), the effect of Mn element partitioning and the structure evolution of bainite under the deformation in intercritical were studied. The microstructure, dislocation density and distribution of alloy elements, especially the volume fraction of retained austenite, were characterized by means of OM, SEM, TEM, EPMA, XRD. The results indicated that the grains of ferrite and the lathes of martensite were refined, the number of the block martensite was decreased, and dislocation density was increased from 1.1988×1014 m-2 to 3624×1014 m-2 after deformation. The mutual movement of dislocation slip increased vacancy concentration and the number of interstitial solute atoms, accelerated the diffusive rate of C atoms and Mn atoms from α phase to the γ phase, and promoted the partitioning effect of the Mn element in the critical region. Eventually, the contents and areas of C、Mn enrichment were increased. By adopting the process of intercritical deformation - hold – austenitizing - quenching - partitioning in bainitic region- quenching（DI&Q&PB）, the amount of retained austenite was increased from 11.5% to 13.9%, the carbon content in retained austenite was increased from 1.14% to 1.28%.

全文下載：https://pan.baidu.com/s/1c2pjJ2o