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针对柳钢高线生产的φ6.5 mm ML08Al低碳冷镦钢盘条近表面出现混晶组织的问题,分析了加热工艺、变形工艺及吐丝温度对产生混晶组织的影响,并对相应的温度制度进行了优化。一加热段迅速将钢坯加热至880~920 ℃,二加热段控制在1 080~1 120℃,均热段控制在1 050~1 090 ℃,各段温度控制精度±12 ℃,加热时间不小于95 min,有利于奥氏体晶粒均匀化,大幅度降低钢坯表面与芯部、头部与尾部温差;结合水箱冷却能力及轧机设备能力,预精轧结束后对轧件快速冷却,将入精轧温度由970 ℃降至860 ℃,将轧件冷却至奥氏体未再结晶区轧制,同时利用精轧机组机架间水冷系统,控制终轧温度为990~1 020 ℃,以避免轧件变形过程温度过高导致奥氏体晶粒异常长大;吐丝温度由原先的950 ℃降至830 ℃。采用优化工艺后,获得了晶粒尺寸均匀的F+P组织,改善了ML08Al盘条冷镦性能。 相似文献
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针对柳钢高线生产的φ6.5 mm ML08Al低碳冷镦钢盘条近表面出现混晶组织的问题,分析了加热工艺、变形工艺及吐丝温度对产生混晶组织的影响,并对相应的温度制度进行了优化。一加热段迅速将钢坯加热至880~920 ℃,二加热段控制在1 080~1 120℃,均热段控制在1 050~1 090 ℃,各段温度控制精度±12 ℃,加热时间不小于95 min,有利于奥氏体晶粒均匀化,大幅度降低钢坯表面与芯部、头部与尾部温差;结合水箱冷却能力及轧机设备能力,预精轧结束后对轧件快速冷却,将入精轧温度由970 ℃降至860 ℃,将轧件冷却至奥氏体未再结晶区轧制,同时利用精轧机组机架间水冷系统,控制终轧温度为990~1 020 ℃,以避免轧件变形过程温度过高导致奥氏体晶粒异常长大;吐丝温度由原先的950 ℃降至830 ℃。采用优化工艺后,获得了晶粒尺寸均匀的F+P组织,改善了ML08Al盘条冷镦性能。 相似文献
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Because Si is a noncarbide forming element, a multiphase microstructure consisting of ferrite, bainite, and retained austenite, at room temperature, can be formed by controlling the thermomechanical process strictly. The cooling schedules must be restricted by the formation of pearlite and cementite. In the present article, a new integrated mathematical model for prediction of microstructure evolution during controlled rolling and controlled cooling is developed for a typical kind of low carbon Si-Mn TRIP steel, which consists of temperature simulation, recrystallization, and transformation models. The influence of Si contents has been thoroughly investigated. The calculated results indicate that Si retards recrystallization, restrains austenite grain growth as well as accelerates polygonal ferrite transformation. 相似文献
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Φ273mm限动芯棒连轧管机组工艺设备特征 总被引:1,自引:1,他引:1
概述了Φ273mm限动芯棒连轧管机组的生产能力、产品规格及品种、工艺选型、生产工艺流程以及锥形辊穿孔、5机架限动芯棒连轧管、12机架微张力定(减)径等主要工序的工艺和装备特点及其技术性能参数;着重介绍了该机组最先进的物料跟踪系统、在线检测质量保证系统、穿孔机工艺辅助设计系统、连轧自动辊缝控制系统、连轧工艺监控系统、微张力定(减)径机工艺辅助设计系统等工艺控制技术。可供国内同类无缝钢管机组的建设借鉴。 相似文献
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对斜轧技术的发展和传统斜轧“横锻效应”的副作用作的介绍和分析,并列举几种新型的斜轧穿孔和轧管设备的特点,提出用三步成型轧管工艺代替老式多工序轧管工艺以改造现有自动轧管机组。 相似文献
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《Journal of Materials Processing Technology》2014,214(9):1962-1970
The no-recrystallization temperature (Tnr) is an important parameter in the design of two-stage rolling schedule to obtain finer grain size. Tnr was obtained both by continuous cooling compression testing and tension-compression testing. However, due to the limitations of experimental installation, both compressing testing and tension-compression testing have a scaling down of practical pass strain and strain rate in rolling mill. The mathematical model that calculates mean flow stress (MFS) can eliminate these limitations and the pass strain and strain applied in mathematical model are approximately equal to the mean value of that in wire-rod rolling mill. Therefore, mathematical calculation is a new method to determine Tnr and the predicted Tnr is similar to experimental results. Due to the high strain rate and short interpass time at the finishing strain of wire rods mills, mathematical modeling is also an effective method to simulate microstructure-evolution in wire rods rolling. An expert system was established to study the microstructure evolution in two-stage rolling through the obtained dynamic recrystallization (DRX) model combined with metadynamic recrystallization (MRX) and static recrystallization (SRX) model in literature. In the present work, it is simplified that the complete metadynamic recrystallization (MRX) is achieved when strain for deformation exceeds critical strain ɛc. It was found that strain accumulation played an important role in finishing rolling. The recrystallization behavior during finishing rolling stage was repeated by static and dynamic model. The predicted austenite grain size and mean flow stress at each pass are expected to provide guidance for appropriate rolling schedule design. 相似文献
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Pierce rolling is the rolling performed first in the production of seamless pipes. In both barrel-type rotary piercing and cone-type rotary piercing, the material is subjected to shearing deformation due to rotary forging. Only a few experimental studies on cone-type rotary piercing have been conducted to obtain the strain components. This paper describes the plastic deformation in the cone-type rotary piercing process using a model piercing mill with modeling clay. First, the model piercing mill is designed and fabricated, and then the effects of the cross-angle and feed angle on the strain components are clarified. It was found that, when the cross-angle is approximately 20°, the longitudinal section of the specimen before rolling becomes the longitudinal section of the specimen after rolling, irrelevant of the feed angle. 相似文献
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A study was undertaken in an attempt to quantitatively describe the rolling process of eutectoid steel rods. Finite element method was employed to model plastic flow and heat transfer in the deformed material, and heat transfer during cooling to ambient temperature. The numerical calculation gave an assessment of the strain, strain rate and temperature distributions in the work piece. This allowed the prediction of the austenite microstructure evolution during the process. Finally, the relationships describing the microstructure-mechanical properties were used to quantitatively characterize the influence of processing parameters on strength of rods after rolling. 相似文献
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简要回顾了限动芯棒连轧管工艺发展,重点介绍了意大利 INNSE 设计的 MPM 连轧管机组和美国艾特纳标准公司设计建于日本的限动芯棒连轧管机组以及西德曼内斯曼钢管公司的限动芯棒连轧管工艺。就穿孔工艺、连轧管工艺及定减径工艺等方面的问题提出了商榷意见。 相似文献
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金属成形过程组织演变的CellularAutomaton模拟技术 总被引:8,自引:0,他引:8
结合金属凝固过程的热成形过程的温度场,浓度场,应力应变场等的数值模拟和结晶,再结晶过程中的热力学,动力学条件,建立了金属成形过程组织演变的宏-微观耦合模型,利用CellularAutomaton方法。依据建立的模型对K417Ni基合金叶片的凝固组织形成过程呼热加工过程的再结晶组织进行了模拟。 相似文献
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在Φ100mm自动轧管机组上,通过改变穿孔轧辊辊型参数和穿孔顶头尺寸,调整穿孔工艺,实现大角度、低转速穿孔速度制度,以及重新设计厚壁管专用定径孔型等技术措施,成功地开发了汽车轴头用Φ98mm×22mm30Mn2热轧厚壁钢管。该产品各项质量指标符合有关标准要求,目前已投入批量生产。 相似文献
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X.K. Liang X.J. Sun Q.Y. Liu H. Dong 《金属学报(英文版)》2006,19(4):265-270
Combined with the technological characteristics of thin slab continuous rolling process (TSCR), dynamic recrystallization of an extremely coarse austenite of low carbon steel is studied by Thermecmaster-Z hot simulator. By the analysis of true stress-strain curves and the observation of microstructures at different deformation stages, the critical stress and critical strain are determined under different deformation conditions. The effect of Z parameter on dynamic recrystallization of coarse austenite is studied. The microstructure evolution in real production is also discussed. 相似文献
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通过分析在线常化工艺生产的E470钢管在两种不同的荒管冷却速度下出现的性能异常情况,结果发现:当在719~600 ℃温度区间荒管冷却速度超过贝氏体临界冷却速度时,因在奥氏体冷却过程中未完全形成铁素体+珠光体而存在部分过冷奥氏体组织,在随后的再加热过程中未转变的过冷奥氏体继续长大形成粗大晶粒,并在随后的冷却中形成了贝氏体组织,最终组织为粗大的贝氏体+铁素体+珠光体,从而大大地降低了材料的冲击韧性。但当在719~600 ℃温度区间荒管冷却速度未超过贝氏体临界冷却速度时,最终组织为细化的铁素体+珠光体组织,获得了良好的强韧性匹配。据此提出为了确保在线常化的效果,应把荒管脱管后的冷却速度作为在线常化工艺的一个重要工艺参数进行控制。 相似文献
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三辊行星轧制过程中ACR紫铜管的组织和性能演变 总被引:4,自引:0,他引:4
采用金相显微镜、布氏硬度仪以及激光热导仪对三辊行星轧制过程中紫铜管的组织和性能进行研究。结果表明:在三辊行星轧制过程中,先后存在着加工硬化和动态再结晶软化两个过程,急剧大变形使粗大的铜晶粒破碎、滑移并产生大量热量,致使变形区温度急剧上升,最终获得了动态再结晶组织;与组织转变相对应,硬度值表现为随变形量的增大而增加,因加工硬化和动态再结晶的共同作用保持稳定,再结晶完成时硬度值下降;由于空洞等缺陷在变形过程中被抵消,材料的热导率增大,再结晶开始后,晶粒变得细小,热导率下降。 相似文献