热压缩变形403Nb叶片钢的静态再结晶行为

通过Gleeble-3500热模拟试验机对403Nb马氏体钢(%:0.16C、11.98Cr、0.03Mo、0.22Nb、0.01V、0.12Ni)在950～1 150℃进行应变速率0.01～10 s~(-1),道次间隔1～100 s的二道次热压缩试验。通过总结已发表的各种静态再结晶数学模型,得出403Nb钢静态再结晶激活能Q_(rex)为168.40 kJ/mol及静态再结晶模型t_(0.5)=6.599 9×10~(-10)ε~(-1.6)(?)~(-0.46) d_0 exp(168400/RT)。结果表明,热压缩道次间隔时间短,钢的晶粒粗大,静态再结晶率低;道次间隔时间长,静态再结晶接近完成,大部分为等轴晶粒;在热压缩过程中,剪应变最大的区域再结晶最完全,晶粒最细小。     

含铌微合金钢低温区静态软化行为

 通过两道次压缩变形实验对含Nb微合金钢静态软化行为进行了研究。结果表明：含Nb微合金钢静态再结晶临界温度随应变量增大而降低;随原始奥氏体晶粒尺寸增加而升高。温度高于静态再结晶临界温度时,含Nb微合金钢的静态再结晶激活能为常数(170589 kJ/mol);温度低于静态再结晶临界温度时,由于Nb的碳氮化物应变诱导析出,含Nb微合金钢的静态再结晶激活能为温度的函数,静态再结晶临界温度可通过再结晶激活能与温度倒数的关系曲线来确定。     

L360管线钢热轧过程静态再结晶行为的研究

奥氏体再结晶行为是影响热轧钢带组织和力学性能的1个主要因素。在热模拟试验的基础上,采用应力松弛法和显微组织观察法,对含Nb和Ti的L360管线钢热轧过程奥氏体静态再结晶行为进行了研究,分析了应变、变形温度、应变速率、原始奥氏体晶粒尺寸对奥氏体静态再结晶的影响。利用线性回归分析,计算出试验钢静态再结晶激活能为203kJ;同时通过回归,得出试验钢热轧过程静态再结晶动力学方程。     

Nb微合金化低碳贝氏体钢的再结晶和应变诱导析出

通过Gleeble-2000热模拟试验机研究了850～1 050℃双道次变形(第1道次60%,20 s-1,第2道次20%,10 s-1)及不同道次间隔时间(10～50 s)对含铌低碳贝氏体钢(%:0.21C、1.50Cr、0.20Mo、0.047Nb)再结晶的影响和应变诱导析出Nb(CN)与热变形奥氏体再结晶的相互作用.结果表明,该钢在1 000～900℃变形10 s后,开始应变诱导析出Nb(CN),延迟静态再结晶过程;通过双道次变形,可获得≤10 μm奥氏体晶粒.     

热轧Nb-Ti钢静态再结晶组织演变及模型研究

在热模拟实验的基础上，对Nb—Ti微合金钢热轧中微观组织的变化进行了分析，介绍了影响组织演变的主要因素及模拟实验方法，对静态再结晶行为和组织演变过程的数学模型进行了研究。研究表明，预报结果与实验结果吻合较好，这种理论处理方法可用来模拟静态再结晶行为。     

高导电性电极扁钢的再结晶规律

为了研究电极扁钢在高温变形时的静态再结晶软化行为,在Gleeble-1500热模拟试验机上对电极扁钢进行双道次热压缩试验,得到了该电极扁钢在不同工艺参数条件下的应力-应变曲线,研究了变形温度和道次间隔时间对电极扁钢静态再结晶行为的影响。根据试验数据结果,计算得到了电极扁钢的静态再结晶激活能,确立了静态再结晶动力学模型。结果表明:道次间隔时间和变形温度对电极扁钢静态再结晶行为的影响比较大,随着变形温度的升高和道次间隔时间的增加,电极扁钢的静态再结晶软化率也增加。     

含铌低碳贝氏体钢再结晶与应变诱导析出研究

利用热模拟技术研究了不同热变形温度条件下双道次变形及不同道次间隙时间等工艺参数对一种铌微合金化低碳贝氏体钢再结晶规律的影响。根据静态再结晶软化率曲线图和双道次热变形后奥氏体晶粒随着间隙时间的晶粒长大趋势,研究了应变诱导析出Nb（C,N）与热变形中奥氏体再结晶的相互作用规律。结果表明,1000—900℃的变形温度内,由于发生应变诱导析出,再结晶过程被延迟,在本试验的道次间隙时间内都为部分再结晶,同时随着变形温度的降低,经过双道次累计应变后,发生完全再结晶,奥氏体晶粒明显细化。     

X120管线钢形变奥氏体的静态再结晶行为

通过在Gleeble-3500热模拟试验机上进行的两道次热压缩变形试验,对含铌微合金管线钢的静态软化行为进行了研究。采用应力补偿法计算了不同变形温度下的静态再结晶百分数。变形温度和弛豫时间对X120钢的静态再结晶影响很大。根据试验数据和静态再结晶动力学方程,计算出X120管线钢静态再结晶激活能为401.56kJ.mol-1。绘制了试验钢的析出动力学(PTT)曲线。     

DC03钢静态再结晶模型的研究

运用正交设计的试验方法,在高温箱式电阻炉内模拟DC03钢高温短时连续退火和低温长时罩式退火工艺条件,采用后插法计算出DC03钢冷轧后各种退火条件下的静态再结晶软化率,研究其与变形程度、退火温度和退火时间的关系.选用Avrami方程建立模型并与热加工两道次间的静态再结晶动力学模型作对比.研究结果表明:退火温度对热加工两道次间的静态再结晶率影响程度比对冷轧后的退火静态再结晶率影响程度大,而保温时间对冷轧后的退火静态再结晶率影响程度比对热加工两道次间的静态再结晶率影响程度大.     

Ti-IF钢多道次变形静态再结晶研究

在热模拟实验机上进行了Ti—IF钢多道次铁素体区变形实验，采用后插法确定了静态再结晶分数。在实验的基础上建立了超低碳Ti—IF钢多道次铁素体变形时静态再结晶动力学模型。研究结果表明，建立的超低碳Ti—IF钢多道次铁素体变形静态再结晶动力学模型与实验结果吻合。     

C-Mn钢高温变形过程再结晶及位错密度的研究

利用Gleeble 15 0 0热力模拟机 ,通过双道次压缩试验 ,计算了C -Mn钢SS4 0 0的热变形激活能 ,建立了静态再结晶模型。模拟计算了因热力学行为的演变引起的静态、动态再结晶以及位错密度等物理冶金现象的变化。研究结果表明 :动态再结晶易在温度较高、应变速率较低的条件下发生 ;静态再结晶在前几道次发生的比较充分 ;粗轧阶段细化晶粒的效果比精轧阶段明显。     

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。     

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。     

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 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.     

Static Recrystallization Behavior of Twin Roll Cast Low-Carbon Steel Strip

 The static recrystallization kinetics of low-carbon steel cast strip was investigated by means of interrupted hot tensile tests. As-cast strip was reheated and soaked and its austenite grain size was similar to the width level of the as-cast columnar structure. The tests were carried out on Gleeble-3500 thermomechanical simulator. The deformation temperature is in the range of 800 to 1200 ℃ with strain rate of 001 to 1 s-1. The prestrain is fixed at 004 to 012, and the inter-hit delay time varies from 1 to 3000 s. Effect of deformation conditions and initial microstructure on static recrystallization behavior was investigated. The activation energy (Qsrx) and Avrami exponent (n) of static recrystallization were determined to have 241 kJ/mol and 054 respectively by linear regression of the experimental results. A kinetics model was proposed to describe the static recrystallization kinetics in low-carbon steel cast strip. The predicted softening fractions are in good agreement with the experimental results, indicating that the proposed equations can give an accurate estimate of the softening behaviors for the low-carbon steel cast strip.     

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。     

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。     

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.