【作者】 王素芬；

【导师】 彭艳；

【作者基本信息】 燕山大学 ， 机械设计及理论， 2013， 博士

【摘要】 冷轧低碳钢薄板主要应用于汽车、家电等行业，冷变形和退火工艺共同影响着产品的最终组织与性能，但其组织调控主要靠轧后退火实现。冷轧生产过程轧制速度快，轧后板带基本接近最终产品形状，退火加热到Ac1温度以上和随后冷却发生一系列组织转变过程决定了低碳钢的最终组织状态，进而决定产品性能，因此对冷轧低碳钢变形及轧后退火加热和冷却过程中组织转变进行预测是冷轧产品组织性能预测研究的热点问题之一。本文以SPHC冷轧基板为研究对象，建立了相关数学模型并结合部分实验对实验钢在轧制变形和轧后退火组织演变过程进行研究，研究结果可作为退火过程工艺制定的依据，所建模型可为低碳冷轧板带组织性能预测提供重要理论指导。冷轧低碳钢的轧制变形不仅决定了产品的最终形状尺寸，并且影响轧后加热过程的组织演变。低碳钢冷轧变形在实验室四辊可逆轧机上进行，结合室温拉伸、显微硬度测试和显微组织观察，基于轧制变形加工硬化机理及其对组织演变和力学性能的影响规律，建立了变形抗力模型和变形储能模型，为冷轧板带组织转变和模拟计算提供了可靠的数据信息。对冷轧低碳钢退火后的性能进行了研究，通过测定不同变形后退火板三个方向（沿轧制方向、垂直于轧向、与轧向成45°方向）上应变硬化特性，确立了再结晶退火冷轧低碳钢的最佳变形范围，完善了冷轧低碳钢再结晶退火生产性能优良带钢产品的内在机制。从相变原理出发，考虑变形储能，采用超组元模型计算了冷轧低碳钢加热发生奥氏体逆相变的相界面浓度、相变驱动力和相变开始温度等热力学参数，建立了包括相变孕育期、相转变量、奥氏体晶粒尺寸预测模型，确立变形量、加热速度、加热温度、保温时间对奥氏体化的影响规律，为生产性能优良冷轧低碳钢的组织预测提供了有力参考。从冷轧低碳薄板的本质特性出发，探讨了冷轧低碳钢在冷却过程发生扩散型相变和非扩散型切变的组织转变原理，建立了先共析铁素体转变和马氏体转变的相变热力学和动力学等数学模型，分析了冷却速度对过冷奥氏体转变的影响规律，并与实验结果对比分析，验证了计算模型的准确性，为冷轧低碳钢轧后连续退火生产高强高韧性产品的组织预测和控制提供了重要的理论依据。对冷轧低碳钢变形及轧后再结晶退火，加热时奥氏体逆相变及随后冷却过程进行了一系列研究，建立的加热、冷却过程组织转变数学模型，对冷轧低碳钢组织预测与控制具有重要意义和理论参考价值。更多还原

【Abstract】 Cold rolled low carbon steel sheet is mainly used in automobiles, householdappliances and other industries, the combined cold deformation and annealing processeffect the microstructure and properties of the final products, but its organization regulatedis mainly achieved by annealing after rolling. For cold rolling production process, therolling speed is fast, the sheet after rolling is close to the final product. It is a series ofstructral transformation process when heated to a temperature above Ac1and subsequentcooling, these determine the final organization state of low carbon steel, and alsodetermine mechanical peroperty. So it become the hot issue study for structraltransformation predicting and controlling of cold-rolled sheet during rolling and annealingheating and cooling process.In the paper, taking cold rolling base plate of SPHC as research object, establishedrelated mathematical model and combining with some experiments studied rollingdeformation and organization evolution process for annealing after rolling theexperimental steel, the results can be used as the basis for constituting annealing processand the established model can provide auxiliary process design for annealing.Cold rolled deformation of low carbon steel determines the final product shapeorganization evolution in the heating process after rolling, rolling deformation wassimulated on the four high reversible rolling-mill in the laboratory, combined with theroom-temperature tensile, microhardness testing and microstructure observation,analysised the work-hardening mechanism and its effected on the microstructuralevolution and mechanical properties, established the deformation resistance model andenergy model, provided reliable data and information for structral change and simulationcalculation of the subsequent heating process.Researched on the performance of the cold-rolled low carbon steel after the annealing,after measured the strain hardening performance for three directions of annealed sheet(along the rolling direction, perpendicular to the rolling direction, a direction of45°withthe rolling direction), established the best deformation range of recrystallization annealed for cold-rolled low carbon steel, it improved internal mechanism of recrystallizationannealing producing excellent performance of strip steel.From the principle of phase transformation, calculated the phase interface’sconcentration, driving force of phase change, starting temperature of phase change andother thermodynamic parameters during heating austenitic inverse phase transformationprocess with ultra element model, established models include the bredperiod model phasechange, change amount model, austenitic grain size prediction model, combining resultsof the physical simulation experiment, analysised the influence principle for austenizationwith heating rate, heating temperature and holding time, provided a strong reference forproducing excellent performance of cold rolled low carbon steel.From the essential characteristics of the cold rolled low carbon steel, diffussed theprinciple of structral changes for diffusion and non-expanding-type phase change duringthe cooling process, transformation thermodynamic and kinetics model of proeutectoidferrite and martensitic transformation, analyzed the influence regular for supercooledaustenite transformation with cooling rate, compared with the experimental results andverified the accuracy of calculation model, provided important theoretical basis fororganizations predicting and controlling of producing high strength and high toughnessproducts with cold-rolled low carbon steel using the continuous annealing production ofResearched cold deformation, crystallization annealing after rolling, the austeniticinverse phase transformation and subsequent cooling process, established structraltransformation mathematical model of heating and cooling process with cold rolled lowcarbon steel, it has a certain theoretical reference value and importance for organizationpredicting and controlling process.更多还原