Q345钢在直轧过程中二相粒子析出对奥氏体晶粒的影响

通过热模拟轧制技术,研究了不同工艺条件下二相粒子析出物对奥氏体再结晶的影响,并对Q345钢直接轧制工艺中C,N化物的析出对组织性能的影响进行了深入探讨.结果表明,利用二相粒子析出可以细化奥氏体晶粒组织,从而改善钢的内部组织和材料的力学性能.     

普通低碳钢奥氏体晶粒细化及其对变形强化相变铁素体晶粒尺寸的影响

研究了普通低碳钢奥氏体昌粒的细化及其对形变强化铁素体晶粒尺寸的影响。结果表明：通过在奥氏体区进行低温（850℃）较大变形，奥氏体晶粒尺寸可细化至约10μm。奥氏体晶粒尺寸对形变相变后的铁素体晶粒尺寸产生影响。奥氏体晶粒细小，则铁素体晶粒细小且均匀。但其影响随着变形温度的降低而逐渐减弱。     

奥氏体—铁素体区循环形变对Q235钢组织的影响

提出了细化金属组织的一种新方法,即奥氏体－铁素体区循环形变。采用该方法研究了铁素体区变形温度、高温区谱形温度,应变速率以及冷却速度对Ｑ２３５钢组织与性能的影响。     

轻质钢的研究进展(二)——铁素体—奥氏体双相轻质钢和奥氏体轻质钢

首先主要阐述了富Al铁素体—奥氏体双相轻质钢和奥氏体轻质钢的微观组织特征、力学性能和强韧化机制。尽管添加Al可以降低钢的密度和提高比强度,但是它会使钢的弹性模量显著降低。针对这一不利属性,介绍了一种切实可行的提高轻质钢(以及碳钢)弹性模量的措施,即利用凝固过程中原位自生高弹性模量的硬质颗粒(如Ti C和Ti B2等)来增强钢的基体。所形成的颗粒增强钢基复合材料可以具有较常规碳钢和富Al轻质钢更高的弹性模量和比弹性模量。     

确定小型试样中残余奥氏体和铁素体数量的便利设备

精确确定残余奥氏体数量对优化低合金TRIP钢十分重要。介绍了一种磁性测量方法及设备,可以方便快捷地确定残余奥氏体的数量。针对工业生产的TRIP钢试样进行的实验表明,该方法准确性很高,与X射线测量结果非常吻合。残余奥氏体数量的精确确定有助于更好地了解冶金工艺,从而优化TRIP钢种的生产。     

奥氏体未再结晶区变形对铁素体晶粒尺寸影响的数值计算

以软件Thermo-Calc所得到的热力学参数为基础，并考虑变形存储能的影响，编制了一个奥氏体连续冷却却相变分析程序，它可用于预制奥氏体非体结晶区变形和以不同冷却速度冷却时的转变过程中及最终组织，利用这一程序的计算结果与实验数据比较吻合。     

C Mn Nb钢在控轧控冷条件下相变后铁素体晶粒尺寸的预测

 基于相变动力学和热力学原理，讨论了椭球形铁素体晶核在奥氏体晶界形核及长大的动力学，在模型中引入变形和冷却的作用，提出了预测C Mn Nb钢经控轧控冷后铁素体晶粒尺寸的方法。用该方法进行的计算机模拟结果和实验结果吻合良好，表明这种方法可用来模拟该相变过程。     

普通碳素钢超细晶临界奥氏体控轧工艺研究

通过在Gleeble-2000热变形模拟机上模拟实验,研究了低温变形条件下的工艺参数对普通低碳钢Q235获得微米级超细晶组织影响规律。利用实验研究结果在型钢轧机上轧出晶粒尺寸约为5μm的400MPa级钢筋,研究表明对于低碳钢Q235利用形变诱导铁素体和铁素体动态再结晶机制在Ae3-Ar3℃附近的临界（亚稳）奥氏体温度范围内变形,可以获得4－6μm等轴均匀的超细晶铁素体。     

Physical Simulation of the Hot Direct Rolling of Steel

Thin slab casting and direct rolling technologies became important for hot strip production to increase the productivity, to lower the investment costs and to increase the energy efficiency. The main objective of our investigation is to gain a better understanding of the microstructural evolution starting from solidification through to the final hot rolled sheet. Small ingots were cast and direct rolled and reheated and rolled, using a thermomechanical testing machine. The differences in the recrystallization kinetics during both production routes were measured using double hit hot compression tests. In addition, multipass deformation trials were performed to reveal differences in the resulting microstructure and the grain size homogeneity. It was found, that the coarse initial microstructure before rolling become negligible after three rolling passes. This means that despite the simple and economical direct rolling similar mechanical strip properties can be obtained in comparison to conventional strip production routes.     

低合金厚板的减量化轧制

 通过挖掘设备潜力,采用奥氏体再结晶区直接轧制+轧后快速冷却工艺在某宽厚板生产线上成功试制了60～85 mm厚Q345系列C Mn低成本厚板,Z向性能稳定达到Z35标准要求。试验结果表明,用该工艺生产低合金厚板可缩短2 min轧制时间,提高了机时产量,促进钢铁工业的可持续发展。     

Effect of Austenite Recrystallization on Microstructure and Properties of Q345 Steel

The Q345 plate steel austenite recrystallization behavior and strain accumulation during rolling were investigated through thermal simulation and rolling. The effect of the recrystallization behavior on the microstructure and properties of the steel was discussed and analyzed. The control principles of the pass reduction in the austenite recrystallization region and partial recrystallization region were established. It is found that to increase the thickness of intermediate billet in the finish temperature interval of 880-820℃ is favorable to grain refinement. The result has been applied to the industrial production of the 3 500 mm plate mill of Shougang Group. The average grain size of the steel plate conforms to ASTM No. 10-12, and the grade of band structure has been reduced to below 1.5.     

铁素体轧制生产超深冲冷轧板

通过铁素体轧制生产超深冲冷轧Ti-IF钢的工业试验,研究了化学成分、工艺制度对热轧IF钢金相组织、织构和第二相粒子析出的影响,分析了热轧IF钢再结晶状态与产品性能的关系,阐述了提高冷轧Ti-IF钢深冲性能的生产控制要素.试验结果表明:在采用适宜的成分、低的加热温度、高的卷取温度和铁素体区强润滑轧制时,热轧板具有粗大的二相粒子和强的{111}织构;与常规轧制相比,冷轧板的r值在横向和45.方向平均提高1.3和1.0,试验冷轧板的最高r值达到了3.23.     

摩擦对IF钢铁素体区热轧和退火织构的影响

采用X射线衍射仪分析IF钢铁素体区热轧织构以及退火织构的演化,在实验室热轧机上进行了IF钢的铁素体区热轧,研究了摩擦对IF钢铁素体区热轧、退火织构的影响。结果表明：无润滑轧制时,钢板表层形成强高斯织构组分{110}〈001〉,弱γ纤维织构,导致再结晶织构中高斯组分强度高,γ纤维织构强度低;润滑轧制时,钢板表层高斯织构组分强度降低,{100}〈011〉、γ纤维织构强度提高,退火后γ纤维织构强度提高。钢板中心受摩擦作用影响较小,轧制过程中发展为较强的α和γ纤维织构,退火后γ纤维织构成为主要织构组分。     

Slow Hot Rolling in Direct Linkage with Thin Slab and Strip Continuous Casting: Effect on the Evolution of Austenite Grain

This work was carried out in context with the development of strip casting with the single‐belt process. In this new process the hot rolling is performed in‐line with considerably lower velocity than in conventional hot rolling. It is of interest to study the effect of low rolling speed on the material properties. Based on a finite element model used to predict the thermomechanical behaviour of the strip in tandem mills, the microstructural evolution of austenite was computed. In order to take account of the non‐isothermal conditions in industrial hot rolling, the material equations for recrystallization and grain growth are modified. The parameter studies were carried out over a wide range of volumetric flow rate extending from that in thin slab casting to that in conventional finishing rolling. They demonstrate that the “slow hot rolling” can produce a fine grain of austenite. Austenite grain evolution was computed for conventional rolling with a seven stand mill and for in‐line hot rolling of strip produced by the single‐belt process. It is found that the final grain size of austenite is about the same for the two processes under the condition that strip thickness behind the last stand is the same.     

可逆式冷轧对钢板织构及铁素体晶粒尺寸的影响

在实验室通过可逆式和连续式冷轧及退火模拟试验,研究了可逆式冷轧对DX51D（低碳铝镇静钢）和DX54D（无间隙原子钢）钢板织构及铁素体晶粒尺寸的影响。试验结果表明：①可逆式冷轧态试样α取向线{115}、{335}织构密度明显大于冷连轧试样,可逆式与连续式冷轧态试样γ取向线{111}织构密度无明显差别;②DX54D可逆轧制退火态试样γ取向线{111}织构密度大于冷连轧试样,其α取向线织构密度则与冷连轧试样相当;③DX51D可逆轧制退火态试样织构密度与冷连轧试样相当;④可逆轧制退火态试样的铁素体晶粒尺寸小于冷连轧试样。     

热轧船板钢时奥氏体相变的规律

通过对现场轧制工艺的模拟,借助热加工模拟试验机研究了变形量、变形温度及变形后的冷却速度,对一般强度船板钢变形奥氏体向铁素体和珠光体转变的影响。实验结果表明:增加变形量,降低变形温度,减缓冷却速度可在不同程度上促进奥氏体向铁素体和珠光体的转变。     

Influence of Prior Austenite Deformation and Non-Metallic Inclusions on Ferrite Formation in Low-Carbon Steels

Effects of prior austenite deformation and non-metallic inclusions on the ferrite nucleation and grain refinement of two kinds of low-carbon steels have been studied. The ferrite nucleation on MnS and V(C,N) is observed. The combination of thermomechanical processes with adequate amounts of non-metallic inclusions formed in low-carbon steels could effectively refine the grain size and the microstructure. Ferrite nucleated on the single MnS or V(CN) inclusions and complex MnS+V(C,N) inclusion. The proper addition of elements S and V could effectively promote the formation of ferrite and further refinement of ferrite grains.