Austenite decomposition during continuous cooling of an HSLA-80 plate steel
Austenite decomposition during continuous cooling of an HSLA-80 plate steel
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DOI：
10.1007/bf02649815
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发表时间：
1996-06
期刊：
影响因子：
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通讯作者：
S. W. Thompson;D. J. Colvin;G. Krauss
中科院分区：
文献类型：
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作者：
S. W. Thompson;D. J. Colvin;G. Krauss
通过金相测量、光学显微镜、扫描电子显微镜、透射电子显微镜和显微硬度测试，评估了HSLA-80钢板（含0.05 C、0.50 Mn、1.12 Cu、0.88 Ni、0.71 Cr和0.20 Mo）在连续冷却过程中细晶奥氏体（晶粒尺寸为10 μm）的分解。在750 °C和600 °C之间，奥氏体在很宽的冷却速率范围内主要转变为多边形铁素体，并且魏氏铁素体侧板经常从这些晶体演变而来。奥氏体的富碳岛在大于约5 °C/s的冷却速率下转变为粒状铁素体、针状铁素体和马氏体（均具有一定程度的残余奥氏体）的复杂混合物。粒状和针状铁素体的形成温度略低于多边形和魏氏铁素体的形成温度。在冷却速率小于约5 °C/s时，富碳奥氏体的区域在比多边形和魏氏铁素体形成的温度低超过100 °C的温度下转变为上贝氏体、下贝氏体和马氏体（加上残余奥氏体）的复杂混合物。铜的相间沉淀物只与多边形和魏氏铁素体结合形成。魏氏铁素体、针状铁素体和贝氏体（上贝氏体和下贝氏体）之间的动力学和显微组织差异表明，这些形态相似的奥氏体转变产物的形成来源和/或机制不同。
Decomposition of fine-grained austenite (10-µm grain size) during continuous cooling of an HSLA-80 plate steel (containing 0.05C, 0.50Mn, 1.12Cu, 0.88Ni, 0.71Cr, and 0.20Mo) was evaluated by dilatometric measurements, light microscopy, scanning electron microscopy, transmission electron microscopy, and microhardness testing. Between 750 °C and 600 °C, austenite transforms primarily to polygonal ferrite over a wide range of cooling rates, and Widmanstätten ferrite sideplates frequently evolve from these crystals. Carbon-enriched islands of austenite transform to a complex mixture of granular ferrite, acicular ferrite, and martensite (all with some degree of retained austenite) at cooling rates greater than approximately 5 °C/s. Granular and acicular ferrite form at temperatures slightly below those at which polygonal and Widmanstätten ferrite form. At cooling rates less than approximately 5 °C/s, regions of carbon-enriched austenite transform to a complex mixture of upper bainite, lower bainite, and martensite (plus retained austenite) at temperatures which are over 100 °C lower than those at which polygonal and Widmanstätten ferrite form. Interphase precipitates of copper form only in association with polygonal and Widmanstätten ferrite. Kinetic and microstruc-tural differences between Widmanstätten ferrite, acicular ferrite, and bainite (both upper and lower) suggest different origins and/or mechanisms of formation for these morphologically similar austenite transformation products.