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。     

高Ti微合金高强钢静态再结晶动力学模型

采用Gleeble-3500热模拟试验机,通过应力松弛法对高Ti微合金高强钢的静态再结晶行为进行研究。结果表明:在高的变形(保温)温度和大的变形量下,静态再结晶进程加快,变形速率对静态再结晶的影响较小;计算出静态再结晶激活能Q_(rex)=276.45 kJ/mol,证实了微合金元素Ti有抑制再结晶的作用;基于Avarami方程确定了试验钢静态再结晶动力学模型。     

Cr对低碳高铌X80管线钢静态再结晶的影响

通过Gleeble-1500D热模拟试验机研究了不同Cr含量的低碳高铌X80管线钢在相同变形工艺条件下的软化行为，采用补偿法计算了试验钢的静态再结晶百分率，分析了变形温度和道次间隔时间对静态软化行为的影响。结果表明：变形温度在900℃～980℃，Cr含量达到一定水平时，可以通过溶质拖曳作用显著降低奥氏体再结晶的进行；Cr的加入还可以增加NbC的固溶度、减小其析出驱动力而延迟其析出时间。     

两种高等级管线钢的奥氏体热变形行为

利用MMS300热模拟试验机在温度为850~1 150℃,应变速率为5 s-1,道次间隔时间为1~400 s的条件下进行了X80及X100管线钢双道次压缩变形试验,测定了不同间隔时间、不同变形温度条件下的软化率。研究结果表明：当道次间隔时间相同时,随变形温度升高,X80及X100管线钢静态再结晶分数均增加,再结晶进程加...     

钛微合金化X70管线钢动态再结晶研究

在Gleeble1 500热模拟实验机上进行了单道次压缩变形实验,研究钛微合金化X70管线钢热变形过程中的动态再结晶行为。实验表明,在变形温度为800～1100℃、变形速率为0.05～15s-1、总变形量为75%的试验条件下,所有试样均发生了动态再结晶。根据实验结果分析了该钢种动态再结晶发生的变形条件,提出了实际生产的工艺控制参数。同时,根据实验数据处理得到了钛微合金化X70管线钢的动态再结晶动力学模型。     

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。     

冷镦钢SWRCH22A的静态再结晶行为

Φ30 mm试验冷镦钢SWRCH22A(/%:0.18C,0.04Si,0.87Mn,0.013P,0.010S,0.039Al)的生产工艺为100 t BOF-LF-150 mm×150 mm坯连铸-轧制。用Gleeble-3500热模拟试验机,在900℃和1 000℃对SWRCH22A钢以变形速率1 s~(-1)、变形量0.25,时间间隔0.5~15 s进行双道次压缩变形试验,得出应力-应变曲线。分析了变形温度和间隔时间对冷镦钢SWRCH22A静态再结晶行为的影响,采用应力补偿法计算了不同变形条件下的静态再结晶百分数。根据试验数据,计算出SWRCH22A钢的静态再结晶激活能为Q_(rex)=249 287 J/mol。参考半经验公式,得到了静态再结晶动力学模型。模型计算与试验结果吻合。     

低碳钢Q235形变奥氏体的静态再结晶

在Thermecmastor-Z热模拟试验机上进行了低碳钢Q235的双道次压缩试验,确定了该钢静态再结晶的动力学方程.结果表明,在大变形量下,即使变形温度较低(850～800℃),应变速率较高时,静态再结晶的速度仍然很快.通过静态再结晶可以将奥氏体晶粒尺寸细化至10～20μm.     

高强低合金钢Q390静态再结晶研究

通过双道次压缩试验,研究了高强低合金钢Q390在奥氏体区的软化行为,分析了变形温度与间隔时间对静态软化行为的影响,采用应力补偿法计算了静态再结晶百分数,确定了Q390钢的静态再结晶激活能,并建立了静态再结晶动力学模型。     

高Ti微合金钢热变形奥氏体的静态再结晶行为

在Gleeable-3800热/力模拟试验机上采用双道次压缩法,研究了一种高Ti微合金钢在奥氏体区变形后道次间隔时间内的静态软化行为,分析了变形温度和间隔时间对静态再结晶行为的影响规律,采用应力补偿法计算了静态再结晶分数。结果表明,变形温度、道次间隔时间对Ti微合金钢静态再结晶行为影响显著,变形温度越高,间隔时间越长,静态再结晶进行得越迅速;确定了Ti微合金钢的静态再结晶激活能为412.56 k J/mol,同时建立了静态再结晶动力学模型。     

X60管线钢再结晶和过冷奥氏体连续冷却相变行为的研究

利用双道次压缩试验,在Gleeble-1500热模拟机上测定了X60管线钢的静态再结晶曲线.利用膨胀法,结合金相法,测定了X60不同冷却速度下连续冷却转变的膨胀曲线,获得了该钢的连续冷却转变曲线(动态CCT曲线);研究了X60管线钢的连续冷却过程中奥氏体转变过程及转变产物的组织;另外,通过对再结晶和CCT曲线的分析,为现场的控轧控冷工艺的制定提供了参考依据.     

X65管线钢晶粒的超细化

基于CSP工艺,通过对X65和X65Re管线钢进行热模拟试验,分析稀土铈元素细化X65管线钢组织晶粒的机理。试验结果表明,稀土铈能抑制X65管线钢再结晶的发生,在热变形过程中有利于应变能累积,在连续多道次变形后,所累积的应变能为变形诱导铁素体相转变提供驱动力,进而细化了组织晶粒。     

X100管线钢的组织、性能及再结晶规律

分析了X100管线钢动态再结晶规律,并绘制了X100管线钢的奥氏体动态再结晶图。在实验室进行了X100管线钢的试制,结果表明:在实验室试制的X100管线钢,屈服强度达到了800MPa,抗拉强度达到了925MPa,并且冲击性能优良,各项性能指标均超过了API标准要求。用SEM对X100管线钢的金相组织进行观察,发现其典型组织为粒状贝氏体,并有少量的贝氏体铁素体。用TEM对其M-A岛形貌进行观察,发现M-A岛宽度约为300nm。     

厚壁X80热轧管线钢生产实践及热加工组织演变分析

摘要：通过Thermomastor-Z热模拟试验机双道次压缩实验,研究了X80管线钢在880～1050℃温度区间的静态再结晶行为,结果表明,实验钢在920℃及以下未发生再结晶,在960℃及以上温度,随道次间隔时间延长,静态再结晶率增加。采用不同卷取温度进行了214mm厚度X80板卷工业试制,精轧开轧温度设为920℃,卷取温度510℃的试制钢组织为准多边形铁素体+粒状贝氏体+MA,卷取温度410℃的试制钢组织为粒状贝氏体+贝氏体铁素体+弥散分布的MA的细小组织,后者的MA尺寸和贝氏体板条尺寸明显小于前者,表现出更优异的低温冲击韧性和DWTT性能。通过TEM发现试制钢中的MA是以马氏体为主的组织,并含有较多纳米级尺寸、以Nb元素为主的Nb/Ti碳氮化物复合析出相,但V的析出量则很有限,此外,高卷取温度试制钢的析出相含量也更高。     

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.     

Recrystallization Behavior of Deformed Austenite in High Strength Microailoyed 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.     

Recrystallization 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.