【作者】 李志杰；

【导师】 刘宏民； 彭艳；

【作者基本信息】 燕山大学 ， 机械设计及理论， 2013， 博士

【摘要】 温轧生产碳素钢可减轻常规热轧生产带来的轧件表面氧化、合金元素烧损、热凸度不易控制等问题，并能够利用温塑性成形过程生成优良的组织。中高碳碳素钢温轧时的组织及其动态演变都与热轧过程不同，宏观表现为流变应力大幅度增加，变形行为出现差异，从而对轧制过程产生影响。碳素钢温轧工艺施行的关键问题是确定合适的轧制温度，并要求轧机具有相应的加工能力。为此，以45钢及65Mn钢为代表，对碳素钢温塑性变形过程的组织演变及力学行为进行研究，考虑变形抗力的变化，计算碳素钢板带温轧时的轧制力，分析碳素钢温连轧过程温度及轧制力的变化规律，为温轧工艺的制定及轧机配置提供理论基础。课题所研究的优质碳素结构钢是广泛使用的基础性的机械装备制造用钢，温轧加工充分利用了材料的成形过程生成性能优良的温轧球化组织，其产品质量的提高对整个机械产品质量的提升具有促进作用。在Gleeble-3500热模拟实验机上，模拟了45钢和65Mn钢的温塑性变形过程，制备出了不同变形工艺条件下的温变形组织，对实验钢温变形组织进行分析，探讨了渗碳体溶解球化和铁素体再结晶机理，阐明了初始组织及变形工艺条件对球化及再结晶的影响，并测试了温变形组织的力学性能，论证了温变形组织与工艺变量之间的关系，最后确立了温加工工艺控制原则。研究结果表明：与GB/T699-1999中的调质处理产品相比，温变形后材料屈服强度、抗拉强度与延伸率均有不同程度的提高，温变形组织的力学性能优于调质处理产品的性能。通过单向圆柱体温压缩实验，研究了实验钢温塑性变形的流变行为，结合应力应变曲线和微观组织观察分析了流变过程材料的微观机制，并对比分析了温变形过程和热变形过程的不同，计算出了曲线特征值、Z参数及变形激活能等参量，得出了变形工艺对变形过程的影响，建立了温加工方程及材料的变形抗力数学模型，模型精度符合使用要求。五道次温变形模拟实验及静态再结晶激活能计算表明，温塑性变形道次间隙软化效应不明显。在卡尔曼采利柯夫解的基础上，考虑温轧过程的流变应力分布和轧辊弹性变形，建立了适用于碳素钢温轧特点的轧制力模型，经过有限元分析对比表明，所建立的非定值变形抗力轧制力模型精度高于传统模型，碳素钢温轧时的轧制压力分布趋势与热轧基本一致，温轧和热轧的变形抗力分布差异对轧制变形区影响不大。对温连轧过程轧制力及轧制温度进行计算，结果表明温连轧过程为升温轧制，开轧温度和变形量对轧制力有重要影响。经过对热轧及温轧工艺的计算，给出了温轧轧制力系数，以便于对温轧轧制力进行工程计算。对温轧生产优质碳素钢涉及的问题进行综合分析，分析结果表明温轧工艺生产优质碳素钢适用于较宽的材料范围，可用于生产板带材、棒线材等多个品种规格的产品，温轧生产碳素钢有利于施行在线连续退火，结合不同的热处理工艺可生产出满足多种机械加工需要的产品，温轧生产优质碳素钢是现实可行的。更多还原

【Abstract】 Surface oxidation of rolled metal, burnout of alloying elements and difficulty tocontrol bring by hot rolling could be mitigated by using warm rolling to producecarbon steel. Warm rolling is also used to generate superior organization. Theorganization and its dynamic evolution during warm rolling are both different from hotrolling. Flow stress is increased and deformation behavior could be different, and thatis expressed in macro which would affect rolling process. Microstructure evolutionand mechanical properties of carbon steel during warm plastic deformation wasresearched represented by45-steel and65Mn-steel. Diversification of deformationresistance was considered and the rolling force of carbon steel during warm rollingwas calculated. Variation of temperature and rolling force of carbon steel during warmrolling was analyzed and provide the theory basis for the making of warm rollingprocesses and the configuration of mill. The high quality carbon steel that used in theresearch is widely used in basic machinery and equipment manufacturing. Warmrolling make the full use of warn rolling spheroidization organization produced duringmachining. The improvement of product quality promoted the quality of entiremechanical products.Warm rolling process of45-steel and65Mn-steel was simulated on Gleeble-3500which is also used for preparation of warm rolling organization with differentproduction process. The warm rolling organization of steel for experiment wasanalyzed. Mechanism of ferrite recrystallization and dissolving spheroidization ofcementite was investigated. Influence of initial organization and process conditions onspheroidization and recrystallization. Mechanical property of warm rolling was testedand relationship between warm rolling organization and process variables wasdemonstrated and then the control principle of warm rolling process was determined.The results show that: the yield strength, tensile strength and elongation of materialwere improved with different degrees comparing with quenched and temperedproducts in GB/T699-1999. So mechanical property of warm rolling organizationexceed that of quenched and tempered products. Products better than quenched and tempered steel could be produced directly without quenched and tempered using warmrolling.Rheological behavior of medium high carbon steel during warm rolling wasresearched by the unidirectional warm compression experiment and materialmicroscopic mechanism during rheological process was observed and analyzedcombining with stress-strain curve and microstructure. The difference of hot rollingand warm rolling was compared and analyzed. Curve characteristic value and Zparameter and deformation activation energy was calculated. Influence of deformationcrafts on deformation process was also obtained. Mathematical model whose accuracyis consistent with requirements for warm processing equation and deformationresistance was build.Model apply to warm rolling of medium high carbon steel in which rolling forceis calculated in subparagraph was build based on the Kalman-Cailicove solutionconsidering the flow stress distribution and elastic deformation of roll system duringwarm rolling. Warm rolling process of carbon steel was simulated byANSYS/LS-DYNA finite element software for explicit nonlinear dynamic analysis.Theoretical calculations was compared with FEM so that deviation of theoreticalrolling force calculation could be analyzed. The reason for deviation was explained bycomparing and analysis of distribution of rolling force.Questions that may be involved in high quality carbon steel using warm rollingwas comprehensively analyzed. The result show that high quality carbon steel isapplicable in wide range of material. The product could be used in producing strip, barand so on. The warm rolling carbon steel was conducive to implement of continuousannealing online. Multiple product that needed by machining could be producedcombining with different heat treatment. It is realistic and feasible to produce highquality carbon steel using warm rolling.更多还原