球扁钢生产问题浅析

介绍了球扁钢的特点及分类,提出了球扁钢的生产工艺及侧弯的解决方法。     

球扁钢轧制扭转变形行为的试验研究

球扁钢由于自身形状尺寸、外在轧制条件、工艺参数的影响,在轧制过程中容易出现扭转变形缺陷.为了探究轧制工艺对球扁钢轧制中扭转变形的影响,本实验运用正交实验法研究轧制压下量、轧制润滑条件、轧件长度三者的综合影响.利用正交原理对试验结果进行极差分析、方差分析,探寻球扁钢在轧制的扭转变形规律,找出其中存在的关系.试验结果表明:球扁钢在轧制过程的扭转变形与轧制压下量和轧件长度有关,而与润滑条件无明显关系.其他条件一定时,在粗孔第二道次时取压下量为轧件原始厚度的21!,轧件长度取轧件原始厚度的10倍进行轧制,能够明显减少球扁钢的扭转变形.     

大规格V-N微合金化球扁钢连续冷却过程中的组织性能分析

针对规格尺寸扩大带来的球扁钢截面性能不均匀问题,利用静态过冷奥氏体连续冷却转变曲线(CCT曲线)和ANSYS有限元多场耦合模拟相结合方法对V-N微合金化设计大规格球扁钢进行了性能预测。同时利用透射电镜、相分析等试验技术对球头和腹板的强化机理进行研究。结果表明：采用V-N微合金化设计18#不对称球扁钢全截面组织为铁素体+珠光体+贝氏体,冷却过程中球头的冷速比腹板冷速慢2℃/s左右,170 s达到最大温差104.6℃,球头和腹板晶粒尺寸差异2.7μm,硬度差异20 HV5。球头较长的高温停留时间使得V(C,N)析出量比腹板更多,析出尺寸更细小。同对比球扁钢相比,采用V-N微合金化设计的试验球扁钢屈服强度提高55～78 MPa,球头与腹板差异从22 MPa减少至1 MPa,显著改善了球扁钢截面均匀性。     

24#船用球扁钢轧制孔型设计

介绍了在Φ650×5＋Φ550×8连轧生产线上试制、生产宽度为240mm的球扁钢的轧制工艺方案和产品情况。     

船用热轧球扁钢的研制与开发

安钢根据市场需求,通过合理的工艺设计及严密的生产组织,研制开发出船用热轧球扁钢。产品力学性能、几何尺寸和表面质量等完全达到国标GB9945—2001及ABS、CCS、BV、LR、GL等五国船规技术要求。     

921A球扁钢热处理工艺研究

921A球扁钢是从钢厂热轧状态进货,经工厂中频淬火调质处理,取样试验合格后上船使用。因为引用标准的修改,进货的厂家也发生了改变,工厂中频淬火调质的工艺不能满足新的标准要求。先对两个厂家的产品进行了相同的热处理,通过金相分析,做力学实验等方式确定了原热处理工艺确实不满足要求,然后通过一系列的实验,找到了满足标准的热处理工艺,并得知:不同钢厂生产出来的921A球扁钢冶炼轧制工艺不会完全相同,热轧后的组织也有很大的区别等结论。     

GB/T9945《热轧球扁钢》国家标准修订综述

简要介绍了热轧球扁钢的发展和技术要求,并研究了新标准的修订情况.     

新型破冰船用热轧球扁钢开发

破冰船是用于破碎水面冰层的船舶,新型破冰船对破碎冰层厚度提出了新的要求,由于需要在低温环境下工作,钢材需具有较高的力学性能。通过合理的成分调整和严格的工艺控制,研发出高强韧性匹配的新型破冰船用热轧球扁钢,产品性能完全符合相关标准要求。     

A36高强度船用热轧球扁钢产品开发

采用低碳、添加Al＋Ti＋Nb＋V合金组合细化晶粒元素的设计成分,优化转炉（LD）或电炉（EC）加LF（VD）精炼工艺,优化Φ400 mm和Φ650 mm生产线轧制工艺,成功开发了A36高强度球扁钢,产品性能达到了船级社认证考核指标。     

高强度球扁钢E36静态再结晶研究

利用双道次压缩的方法,研究了高强度球扁钢E36在变形间隔时间内奥氏体的软化行为。结果表明：E36钢在900℃以上变形时,再结晶软化速度较快,在30—50s内均已完成完全再结晶,在900℃时,再结晶过程明显减慢,弛豫1000s再结晶份数还不到50％,再结晶孕育期增至40s左右。为制定合理的细化晶粒轧制工艺提供实验和理论基础。     

半连轧机组生产球扁钢孔型设计实践

结合球扁钢的断面特点、球扁钢轧制变形规律的分析以及多年异型钢生产实践,开发出了一套适合半连轧机组上生产球扁钢的弯腰闭式轧法孔型系统,解决了球扁钢孔型设计在半连轧线生产的技术难题;同时采用了行业内最先进的“连续式电感应加热”方法,解决了特用钢加热不均、氧化控制困难的瓶颈;生产的球扁钢产品质量水平较高,满足国家一些重点型号船舶建设的需要。     

55CrMnA弹簧扁钢产品开发

介绍了 5 5CrMnA弹簧扁钢产品的开发过程及其生产中的冶炼和轧制中的注意事项。     

Grain growth behaviour of an AISI 422 martensitic stainless steel after hot deformation process

The metadynamic softening behaviour and grain size refinement of an AISI 422 martensitic stainless steel in the temperature range of 950–1150°C was investigated by double-hit compression tests. The deformed specimens were held at deformation temperature with delay times of 5–300?s after achieving a strain of 0.3. Based on the experimental results, a model was established for estimation of a softening fraction at different deformation parameters, and the softening fraction was compared with a recrystallised fraction. A major deviation was observed at the beginning of interpass time denoting a significant contribution of recovery to the fractional softening (FS). However, by increasing the time and temperature, the difference between the FS and recrystallised fraction is reduced. The finer grain size was achieved by prior fine pre-austenite grain and lower secondary deformation temperature. The initial grain size of 53?µm decreased down to 32 and 19?µm at the deformation temperatures of 1020 and 940°C, respectively. The austenite grains have considerable growth at a temperature higher than 1020°C, while the grain coarsening is negligible at lower deformation temperatures.     

钛微合金化X70管线钢热变形方程的建立

在Gleeble热模拟实验机上进行了单道次压缩变形实验,研究了变形温度、变形速度和变形程度等对钛微合金化X70管线钢热变形行为的影响。实验变形温度为800-1100℃,变形速率为0．05～15／s,总变形量为75％。在实验变形条件下,所有试样均发生了动态再结晶。根据应力一应变数据,确定了钛微合金化X70管线钢的变形激活能Qdef,并建立了Z-Hollomen参数方程。     

FNN model for carbide size of M50 steel during hot deformation

Isothermal compression of M50 steel was carried out on a Gleeble-3500 simulator at the deformation temperatures ranging from 1223 to 1423 K and the strain rates ranging from 10 to 70 s^??1. The relationship between the deformation temperature, strain rate, strain and the carbide size of M50 steel was acquired by simulating the isothermal compression via finite element method, and a fuzzy neural network model for predicting the carbide size during hot deformation was established. The maximum and average difference between the experimental and the predicted carbide size were 9.2 and 4.1% respectively. Applying the present fuzzy neural network model, the effect of the deformation temperature, strain rate and strain on the carbide size of M50 steel during hot deformation was analysed.     

F45MnVS钢热变形本构方程

为了建立可以满足计算精度的F45MnVS钢高温塑性变形本构关系模型,利用Gleeble-3500试验机完成了热模拟等温压缩试验,获得了变形温度为800～1 000℃、应变速率为0.01～10s-1、变形量为0～70%时的金属流变行为。结果表明,应力随应变的变化具有明显动态再结晶特征,应力随变形温度的降低、应变速率的增加而增大;基于对Arrhenius方程和Zener-Hollomon参数的解析,获得了热变形激活能Q,建立了峰值应力本构模型;基于应力-位错关系和动态再结晶动力学,建立了加工硬化-动态回复和动态再结晶两个阶段的机理型本构模型,用于描述不同变形温度和应变速率时应力与应变之间的关系;采用所建模型完成了不同变形条件的应力应变预测,与试验结果的对比分析表明,相关系数为0.997,吻合度高。     

Effect of hot deformation and Nb precipitation on continuous cooling transformation of a high-Nb steel

In this work, the effects of hot deformation on continuous cooling transformation of a high-Nb steel were investigated on a Gleeble 3500 thermal simulator. The amounts of dissolved Nb were determined by inductively coupled plasma-atomic emission spectrometry. Furthermore, the effects of hot deformation and Nb precipitation on phase transformation were discussed. Results showed that high-Nb steel is suitable for acicular ferrite pipeline steels because the acicular ferrite microstructure can be obtained in a wide cooling rate range. Hot deformation strongly accelerates the polygonal ferrite transformation and increases the critical cooling rate to obtain a full acicular ferrite microstructure. Moreover, hot deformation markedly refines the final microstructure and improves the mechanical properties of acicular ferrite obtained at a high cooling rate. However, hot deformation can also promote Nb precipitation during holding and even cooling at low rates after hot deformation. Nb precipitation dramatically promotes the polygonal ferrite, weakens the effect of Nb in solution on phase transformation and strengthening, and decreases the microhardness.     

On the hot tensile deformation behavior of an AISI 316LN stainless steel

The hot deformation characteristics of AISI 316LN stainless steel were studied in the temperature range of 1123–1323 K and strain rate range of 10⁻⁴–10⁻¹s⁻¹ by carrying out tensile tests. The flow stress, ultimate tensile stress and percentage elongation were found to be strongly dependent on the temperature and strain rate. The critical strain required for the initiation of dynamic recrystallisation and peak strain were determined at each condition and their variation with temperature and strain rate studied. The deformation behavior was analyzed using a generic model for high temperature deformation and deformation parameters were computed. The variation of the true activation energy with strain for rate controlled high temperature tensile deformation was obtained. Microstructural studies were carried out on tested samples and the results of all the above studies are presented.     

轧制变形抗力数学模型的发展与研究动态

建立变形抗力数学模型对变形抗力预测和电子计算机在线控制生产的普及具有重要意义。从传统解析法和人工神经网络法两个角度,系统介绍了国内外建立变形抗力模型的发展应用与研究动态,结合建模中存在的问题,针对性地提出了一些建议。