D36船板热变形奥氏体再结晶规律的研究

采用Gleeble 3500热模拟机,研究了D36船板奥氏体的再结晶温度以及奥氏体的变形温度、变形量和变形速率对热变形奥氏体再结晶的影响。结果表明:当变形速率为0.1~1 s-1、温度达到950℃时,开始发生动态再结晶;当变形速率为5 s~(-1)、温度在1 000~1 050℃时,发生动态再结晶;当变形速率为10 s~(-1)时,不发生动态再结晶。当变形温度为1 050℃、单道次变形率在10%~20%时,D36钢在10s左右的道次间隔内发生了完全的静态再结晶。当单道次变形率在20%以上,D36钢在5 s左右的道次间隔内发生了完全的静态再结晶。     

含铌微合金带钢精轧过程中的再结晶行为

介绍了含铌微合金带钢在精轧过程中的再结晶行为。在不同条件下，含铌钢将发生静态再结晶、动态再结晶和亚动态再结晶，而且沉淀的析出对再结晶有不同程度的影响。     

WNQ570桥梁钢的静态再结晶行为

 为了研究轧制工艺对WNQ570桥梁钢再结晶行为的影响,采用Gleeble-3500热模拟试验机模拟了其双道次热变形过程,测试了试验钢的应力-应变曲线,建立了静态再结晶晶粒体积分数随变形温度和道次间隔时间变化的关系模型,分析了应变诱导析出抑制对静态软化行为的影响。研究结果表明：静态再结晶体积分数随变形温度的提高或道次间隔时间的延长而增大,应变诱导析出抑制静态再结晶的进行;静态再结晶激活能为240.47kJ/mol。研究结果为制订试验钢二阶段控轧工艺提供了依据。     

高碳钢高速变形的模拟及再结晶规律的研究

高碳钢试样在Ｇｌｅｅｂｌｅ－２０００试验机上进行高温多道次高变形速度的变形试验,高应变速率下的变形屈服应力服从Ｚｅｎｅｒ－Ｈｏｌｌｍａｎ因子（Ｚ＝Ａｏ＾ｎ＝εｅｘｐ（Ｑ／ＲＴ）的变化。高线预精轧时,发生道次间静态再结晶;而精轧时由于道次时间短,有道次应变积累现象,应变积累达到临界变形量后,引起动态再结晶发生。     

403Nb叶片钢高温热压缩静态再结晶研究

利用Gleeble-3500热模拟试验机对403Nb马氏体叶片钢进行二道次高温热压缩试验,对不同温度、应变速率、道次间隔下发生的静态再结晶进行了研究和计算,得到403Nb静态再结晶、静态再结晶激活能和静态再结晶晶粒尺寸模型。     

不同w(C)对20MnSi钢的热变形再结晶的影响

利用在Gleeble热模拟试验机上进行的单道次和双道次压缩试验研究20MnSi钢和30MnSi钢的动态再结晶和静态再结晶,得到了它们的再结晶激活能,为正确制订控制轧制工艺提供了依据.     

不同型号Gleeble热模拟试验机比对试验

采用首钢集团有限公司技术研究院Gleeble 2000D型热模拟试验机和中国钢研科技集团有限公司Gleeble 1500型和Gleeble 3800型热模拟试验机进行了动态再结晶、静态再结晶和相变比对试验。结果表明，采用Gleeble 2000D型热模拟试验机测得的静态再结晶曲线存在波动和形态异常现象，但其与Gleeble 1500型和Gleeble 3800型热模拟试验机测得的动态再结晶和静态再结晶试验规律一致；无论是动态相变还是静态相变，采用Gleeble 3800型热模拟试验机测得的相变温度均高于Gleeble 2000D型热模拟试验机。     

薄板坯连铸连轧流程钛微合金钢控制轧制技术

 重点阐述了薄板坯连铸连轧流程钛微合金钢的控制轧制模式及其机理。基于应力松弛试验和双道次压缩热模拟试验,研究分析了薄板坯连铸连轧钛微合金钢的奥氏体再结晶动力学。研究结果表明,轧前铸态粗大奥氏体组织经F1高温大压下后可实现完全静态再结晶;铸坯中固析TiN粒子可以有效阻止奥氏体再结晶晶粒的长大,实现再结晶区控轧。固溶钛的溶质拖曳作用以及形变诱导析出的TiC粒子对奥氏体再结晶具有抑制作用,可以阻止奥氏体再结晶的发生,实现未再结晶区控轧。     

贝氏体非调质紧固件用钢静态再结晶行为分析

为分析贝氏体非调质紧固件用钢的静态再结晶行为,在Gleeble 3500热模拟试验机上进行了双道次压缩试验,并计算了静态再结晶软化率。研究表明,所研究钢种的奥氏体在1 050℃以上易于发生静态再结晶,在850℃以下静态再结晶发生困难;所确定的再结晶模型1可用于预测所研究钢种的静态再结晶的发生情况;利用道次间的静态再结晶细化奥氏体,适宜的轧制温度应控制在950~1 050℃,热机轧制温度应控制在850℃左右。     

冷轧基板SPHE静态再结晶行为研究

 利用Gleeble-3500热力模拟试验机研究了冷轧基板SPHE钢的静态再结晶行为, 通过对奥氏体再结晶行为的研究,得到试验钢发生静态再结晶时变形温度越高,发生静态再结晶越容易。试验钢在900、950和1000℃变形过程中停留不同时间,再结晶分数出现了个别点下降,是试验检测误差所致;随着停留时间的增加,由于溶质原子和碳化物等第二相质点的析出,引起了再结晶速率降低。试验钢SPHE发生静态再结晶的激活能为23987kJ/mol。     

热连轧生产船板钢E36静态再结晶行为研究

基于热模拟双道次压缩试验,研究了热连轧生产过程中船板钢E36奥氏体变形区不同变形温度、变形间隙时间内的软化行为,分析了变形温度和轧制变形间隙时间对静态再结晶软化率的影响,结果表明：变形温度是影响再结晶的最主要因素,在达到轧制变形温度时,随着轧制间隙时间的延长,再结晶软化率呈现逐步递增的趋势。通过金相分析,得出了最佳轧制...     

Numerical Simulation of Austenite Recrystallization in CSP Hot Rolled C-Mn Steel Strip

An integrated mathematical model is developed to predict the microstructure evolution of C-Mn steel during multipass hot rolling on the CSP production line,and the thermal evolution,the temperature distribution,the deformation,and the austenite recrystallization are simulated.The characteristics of austenite recrystallization of hot rolled C-Mn steel in the CSP process are also discussed.The simulation of the microstructure evolution of C-Mn steel ZJ510L during CSP multipass hot rolling indicates that dynamic recrystallization and metadynamic recrystallization may easily occur in the first few passes,where nonuniform recrystallization and inhomogeneous grain size microstructure may readily occur;during the last few passes,static recrystallization may occur dominantly,and the microstructure will become more homogeneous and partial recrystallization may occur at relatively low temperature.     

Austenite Recrystallization and Controlled Rolling of Low Carbon Steels

The dynamic recrystallization and static recrystallization in a low carbon steel were investigated through single-pass and double-pass experiments. The results indicate that as the deformation temperature increases and the strain rate decreases, the shape of the stress-strain curve is changed from dynamic recovery shape to dynamic recrystallization shape. The austenite could not recrystallize within a few seconds after deformation at temperature below 900 ℃. According to the change in microstructure during deformation, the controlled rolling of low carbon steel can be divided into four stages： dynamic recrystallization, dynamic recovery, strain-induced ferrite transformation, and rolling in two-phase region. According to the microstructure after deformation, the controlled rolling of low carbon steel can be divided into five regions： non-recrystallized austenite, partly-recrystallized austenite, fully-recrystallized austenite, austenite to ferrite transformation, and dual phase.     

X70管线钢热连轧过程奥氏体再结晶、晶粒尺寸和平均流变应力的预测

在考虑动态、亚动态再结晶及静态再结晶的基础上,建立了X70管线钢的物理冶金模型,并应用于板带钢热连轧过程奥氏体再结晶、晶粒尺寸和流变应力的预测.结果表明,在合理的温度和压下条件下,应变累积可导致在精轧过程出现动态 亚动态再结晶行为,促进奥氏体晶粒的进一步细化.终轧温度的降低可引起奥氏体晶粒的粗化和残余应变的显著提高.建立了考虑晶粒尺寸和残余应变影响的平均流变应力(MFS)的人工神经网络预测模型,大大提高了热连轧过程MFS预测精度.     

Recrystallization behavior of twin roll cast low carbon steel strip

The dynamic and static recrystallization behaviors of twin roll cast low carbon steel strip were investigated with an attempt to provide guiding deformation parameters for the on line hot rolling.In order to investigate dynamic recrystallization behavior,as cast strip was reheated and soaked with austenite grain size similar to the width level of the as cast columnar structure.Tensile test was used and the deformation temperature is in the range of 900℃to 1 100℃and strain rates are 0.01 s^-1,0.1 s^-1,1 s^-1.The activation energy and stress exponent were determined as 306kJ/mol and 4.69 respectively.The ratio of critical strain to the peak strain is 0.65,and that of critical stress to the peak stress is 0.92.The dependence of the peak strain on the initial grain size and Zener - Hollomon parameters Z isε_p =9.1×10^-4×D₀^0.48Z^0.13.The kinetics of the dynamic recrystallization and recrystallized grain size was predicted using models published.The as cast coarse austenite were dramatically refined after complete dynamic recrystallization.For static recrystallization,the tensile test was carried out on Gleeble -3500 thermo - mechanical simulator.The deformation temperature is in the range of 800℃to 1 200℃with strain rate 0.01 s^-1 to 1s^-1.The pre strain is fixed at 0.04 to 0.12 and the inter-hit delay time varies from 1 s to 3 000 s.The activation energy and Avrami exponent of static recrystallization were determined as 241 kJ/mol and 0.54 respectively.A kinetics model was proposed to describe the static recrystallization kinetics.The predicted results were in good agreement with the experimental results.     

低碳钢热变形奥氏体的再结晶行为

对热变形奥氏体的再结晶动力学和微观组织演变进行了模拟计算,对晶粒尺寸的模拟值和实测值作了比较,分析了化学成分对动态再结晶率的影响以及残余应变与变形温度的关系.结果表明:在温度较高、应变速率较低的条件下容易发生动态再结晶,随着变形温度的降低,发生动态再结晶的几率减小,而静态再结晶在前几道次进行得比较充分,随后进行得不充分,增加碳和锰的含量可以促进动态再结晶的发生,残余应变随变形温度的降低而增大,晶粒尺寸的模拟值和实测值吻合较好,表明所选用的模型有一定的参考价值.     

Static Recrystallization Kinetics Model After Hot Deformation of Low-Alloy Steel Q345B

The static recrystallization behavior of low-alloy steel Q345B during double-pass hot compression deformation tests was investigated in the temperature range of 900-1000 ℃,the true strain range of 0.15-0.25 and the interpass time range of 0.5-50 s on Gleeble-3500 thermo-simulation machine.The results show that static recrystallization during the interpass time is observed.As the deformation temperature and strain increase,softening caused by static recrystallization is obvious.According to the analysis and calculation of thermo-simulation data,the static recrystallization activation energy was obtained and static recrystallization kinetics model was built.Finally,the error analysis of static recrystallization kinetics model proved that the model had good accuracy.Therefore,this model provides a theoretical basis for static recrystallization(SRX)and will contribute to the development of multipass hot rolling process,in order to control the rolling process more accurately.     

Recrystallization Behavior Design for Controlling Grain Size in Strip Rolling Process

To promote effectively dynamic recrystallization and obtain a homogeneous distribution of ultrafine grain size in strip finish rolling process,the behavior of static and dynamic recrystallization must be appropriately designed to provide an ultrafine austenite microstructure without mixed grain size.The design of rolling schedule was analyzed based on the control of the recrystallization behavior to achieve ultrafine grain size in the strip rolling process of niobium microalloyed steel.The experimental simulations were presented to validate the twice dynamic recrystallization design to achieve ultrafine grain size control.     

Recrystailization Behavior of Deformed Austenite in High Strength Microalloyed Pipeline Steel

Using methods of single-hit hot compression and stress relaxation after deformation on a Gleeble 1500D thermomechanical simulator,the curves of flow stress and stress relaxation,the microstructure and the recrystallization behavior of Nb-V-Ti high strength microalloyed low carbon pipeline steel were studied,and the influence of the thermomechanical treatment parameters on dynamic and static recrystallization of the steel was investigated.It was found that microalloying elements improved the deformation activation energy and produced a retardation of the recrystallization due to the solid solution and precipitation pinning.The deformation conditions such as deformation temperature,strain,and strain rate influenced the recrystallization kinetics and the microstructure respectively.Equations obtained can be used to valuate and predict the dynamic and static recrystallizations.