莱钢成功开发超细晶粒钢新工艺

日前,山钢集团莱钢棒材厂借助自主研发的超细晶粒钢生产工艺,采用二级钢坯原料成功轧制出符合三级钢标准的螺纹钢筋,经过对产品的周期性检验,钢筋的强度、塑性等指标均符合国家相关标准要求,超细晶粒钢生产工艺实施     

鞍钢超细晶粒钢的开发

主要介绍了鞍钢超细晶粒热轧卷板和线材的研制情况，总的研制思路是结合鞍钢设备的实际情况，探索低成本的超细晶粒钢的生产工艺路线。开发的产品已能稳定的大批量生产，使用性能良好。     

800MPa级超细晶粒钢研究现状和发展趋势

800MPa 级超细晶粒钢是通过多向变形热处理,大角度交叉轧制,大变形应变诱导动态相变和 铁素体动态相变,大变形诱导铁素体相变,弛豫析出控制相变,促进针状铁素体形成等轧制技术,将钢中的晶 粒尺寸由10 μm 降到1 μm 以下,从而达到高强韧性的一种低碳(0.05%C)微合金化钢。介绍了国内外800MPa级超细晶粒钢的理论研究、生产工艺和焊接技术的新进展和今后发展趋势。     

钢铁材料晶粒的超微细化（日）

阐明钢铁材料晶粒超微细化的发展状况，详细介绍了利用钢中各种相变的最后的热机械处理以及利用适当的回复和再结晶现象的强烈变形得到超细晶粒钢的两种方法，汇集了超细晶粒钢的显微组织特征和机械性能，讨论了超细晶粒钢的未来发展和前景。     

微米级超细晶粒钢细化工艺的研究进展

超细晶粒钢是近年来钢铁材料研究的热点,本文综述了微米级超细晶粒钢细化技术的主要研究成果,探讨了微米级超细晶技术的理论依据,并且介绍了它的工业生产情况。     

超细晶粒钢及其焊接性

介绍了超细晶粒钢的特点,针对这些特点,讨论了超细晶粒钢的焊接性,其中包括HAZ性能、焊缝性能、HAZ和焊缝的裂纹倾向等。     

超细晶粒钢的制备原理及技术

 介绍了国内外超细晶粒钢的发展情况;阐述了晶粒细化对钢铁材料综合性能的影响,从微合金化、形变诱导相变、热处理和新型机械控制轧制技术及磁场或电场处理等方面介绍了获得细化晶粒钢的关键技术,最后从实际应用角度出发,提出了超细晶粒钢生产及应用中存在的问题。     

超细晶粒钢的显微组织

分析了以普碳钢成分生产的超细晶粒钢的显微组织。结果表明：工业生产的超细晶粒钢的显微组织由铁素体和珠光体组成,铁素体的晶粒尺寸为4—5μm,组织中珠光体所占体积分数较低。珠光体中渗碳体以短棒状或颗粒状存在,细小的铁素体晶粒使晶粒内的位错塞积密度减少,有利于提高钢的强度和韧性。     

攀钢首次研制超细晶粒钢

由攀钢和钢铁研究总院承担的国家 973项目“新一代钢铁材料重大基础研究”所属课题“厚规格热连轧超细晶粒钢生产技术研究” ,最近在攀钢钢研院进行了第一轮实验室试验。试验初步研究了变形诱导铁素体相变对形成超细晶粒组织的影响 ,制取了晶粒细化的普碳钢和低合金钢 ,为下一轮试验和最终确定最佳的化学成分及轧制工艺制度 ,开阔了思路 ,积累了经验。超细晶粒 (～ 1μｍ)钢具有极高的强度和极高的韧性 ,是一个全球性的研究大课题 ,目前国内外尚处于实验室试验阶段。大量的研究表明 ,采用变形诱导相变是获得超细晶粒钢的主要工艺路线之一 ,…     

超细晶粒高强度钢的延迟断裂行为

惠卫军等从降低应力集中和夹杂元素晶界偏聚等角度对超细晶粒高强度钢的延迟断裂行为进行了探讨。对于微合金化处理的42CrMoVNb钢，通过快速循环热处理的方法获得最小2μm的超细奥氏体晶粒，     

Fabrication of Nano/Ultra-Fine Grained IF Steel via SPD Processes: a Review

The grain size of polycrystalline materials plays a major role in dictating many critical properties including the strength and resistance to plastic flow. Nano/ultra-fine grained steels have the potential to exhibit outstanding physical, mechanical and chemical properties, which could, in principle, lead to new applications and novel technologies. Interstitial free (IF) steels in the coarse-grained condition possesses high ductility but low yield strength due to the decrease in the solid solution hardening effect of the interstitial atoms. Enhancing the strength with adequate ductility may increase the potential applications of IF steel sheets in new applications like those in aviation or defense industries. In fact, the overall trend in the development of IF steels are towards the high strength variety that will allow weight saving through down gauging. Considering the monophase microstructure of IF steel, strengthening methods to enhance its mechanical properties are limited and grain refinement seems to be the most feasible method. The most attractive method for the production of nano/ultra-fine grained IF steel is severe plastic deformation (SPD) processes. Therefore, this review is concerned with the production of nano/ultra-fine IF steel by using SPD methods such as accumulative roll bonding and equal channel angular pressing processes.     

轧制压下量对低碳超细晶粒钢Q235B组织及性能的影响

低碳钢Q235B奥氏体化后淬火得到马氏体组织,然后在室温下进行多道次轧制,总压下量分别为50%与70%,随后在500～650℃退火2 min制备低碳超细晶粒钢,研究轧制压下量对超细晶粒钢组织及性能的影响。采用光学显微镜和扫描电子显微镜观察显微组织演变,用能谱仪分析析出物颗粒化学成分,在Instron-5969拉伸试验机上进行拉伸实验。结果表明,冷轧+退火马氏体起始组织可以制备超细晶钢,强度相比原始钢强度提高近一倍。此外,随着压下量的增加,再结晶温度降低,渗碳体颗粒易长大,不利于超细晶钢机械性能的提高。相同退火工艺下,压下量增加,铁素体晶粒及渗碳体尺寸长大,其综合机械性能降低。     

细晶粒低碳钢的轧制工艺对显微组织的影响

 细晶粒低碳钢生产的关键技术在于控轧控冷。前人虽对轧制温度、压下制度、冷却速度等对组织的影响的一般规律做了研究总结,但在生产实际中,需对成本、能耗、板形及轧机负荷能力等进行综合考虑,因此需要优化工艺参数。利用热模拟机对超细晶粒钢板的生产过程进行了模拟,工艺参数尽量贴近生产实际。对试样的微观组织进行了观察,总结了冷却速度、压下量分配制度、终轧温度等工艺参数对组织的影响规律,为在线轧制工艺的制定提供了帮助。     

Tensile Properties of Medium Mn Steel with a Bimodal UFG α + γ and Coarse δ-Ferrite Microstructure

While the tensile strength and elongation obtained for medium Mn steel would appear to make it a candidate material in applications which require formable ultra-high strength materials, many secondary aspects of the microstructure–properties relationships have not yet been given enough attention. In this contribution, the microstructural and tensile properties of medium Mn steel with a bimodal microstructure consisting of an ultra-fine grained ferrite + austenite constituent and coarse-grained delta-ferrite are therefore reviewed in detail. The tensile properties of ultra-fine-grained intercritically annealed medium Mn steel reveal a complex dependence on the intercritical annealing temperature. This dependence is related to the influence of the intercritical annealing temperature on the activation of the plasticity-enhancing mechanisms in the microstructure. The kinetics of deformation twinning and strain-induced transformation in the ultra-fine grained austenite play a prominent role in determining the strain hardening of medium Mn steel. While excellent strength–ductility combinations are obtained when deformation twinning and strain-induced transformation occur gradually and in sequence, large elongations are also observed when strain-induced transformation plasticity is not activated. In addition, the localization of plastic flow is observed to occur in samples after intercritical annealing at intermediate temperatures, suggesting that both strain hardening and strain rate sensitivity are influenced by the properties of the ultra-fine-grained austenite.     

普通C-Mn钢超细晶中厚板的带状组织

采用Gleeble2000热模拟试验机研究了普通C-Mn钢的再结晶规律，在实验室轧机上进行了C-Mn钢超细晶中板的轧制，并且在首钢中厚板厂工业轧机上进行了超细晶中厚板的工业试制，研究了工艺条件对中厚板带状组织的影响，分析了带状组织产生的机理。研究结果表明，在靠近静态相变温度Ar3附近的未再结晶区进行大变形量轧制(形变诱导相变)，不仅可以使板材的铁素体晶粒细化甚至获得超细晶组织，而且普通C-Mn钢中厚板中的带状组织减轻1～2级；降低精轧开轧温度有利于减轻板材的带状组织；在未再结晶区控轧有利于减轻板材的带状组织；随着未再结晶区形变量增加，板材的带状组织减弱。     

超细晶钨及其复合材料的研究现状

综述了自上而下和自下而上两种方法制备超细晶钨块体材料的研究现状.详尽概述了强塑性变形工艺、特殊烧结工艺制备超细晶钨的基本原理和特点.分析讨论了在强塑性变形加工及其粉末冶金法制备超细晶钨的影响因素及晶粒细化机制,指出了合理地采用弥散强化相,结合特殊烧结工艺和后期热变形加工工艺将是制备超细晶钨发展的主要方向.     

变形速率对普碳钢中形变诱导铁素体相变的影响

针对普通碳素钢(Q235类型),研究在Ae3～Ar3温度区间内采用形变诱导铁素体机制获得超细晶铁素体的数量与变形速率的相互关系。实验在Gleeble 1500热模拟实验机上进行。实验方案为：1000℃保温2min,以10℃／s的速度冷却到变形温度[Ae3(840℃)至Ar3(780℃)],变形量为30％～50％,变形后立即水淬。结果表明,在840℃变形时,随着变形速率的增大,形变诱导铁素体量增多;在780℃变形时,随着变形速率的增大,形变诱导铁素体量减少;而在840-780℃之间变形时,变形速率存在最佳值,在该值下诱导生成的铁素体量最大。     

安钢微合金化钢生产技术进展

本文简要回顾了近20年来安钢产品创新的4个阶段和取得的显著成果.自1994年安钢开始开发微合金化钢,已广泛应用于建筑、机械、容器、桥梁和造船等行业;并相继研究开发了铌钒微合金化技术、电炉流程微合金钢铸坯质量控制、细晶粒钢生产和控轧控冷等新技术.论文总结了安钢微合金化钢的系统研发情况,分析了产品技术创新成果和品种生产进展;提出了实施精品生产战略的技术措施.     

Austenite Grain Refinement and Isothermal Growth Behavior in a Low Carbon Vanadium Microalloyed Steel

The austenite grain refinement through control of the grain growth during reheating process after thermomechanical controlled process(TMCP)in a vanadium microalloyed steel was achieved.The formation of ultra-fine grained austenite was attributed to the high density of austenite nucleation at the ferrite/martensite structure and to the inhibition of austenite growth by(Ti,V)C particles at the relatively low reheating temperature.Corresponding with the precipitation behavior of(Ti,V)C with temperature,the growth behavior of austenite in the vanadium microalloyed steel could be divided into two regions.At lower reheating temperature,austenite grains grew slowly,and ultra-fine grained austenite smaller than 5μm was successfully obtained.By contrast,the austenite grains grew rapidly at high temperature due to the dissolution of(Ti,V)C particles.According to the measured and predicted results of austenite growth kinetics,two models were developed to describe the growth behavior of austenite grains in two different temperature regions,and the apparent activation energy Qappfor grain growth was estimated to be about 115 and 195kJ/mol,respectively.     

SS400超细晶粒钢及其焊接接头的疲劳裂纹扩展速率

SS400钢是一种细晶强化的新一代钢铁材料．焊接对其疲劳性能的影响是人们关注的问题。笔者参照美国材料试验学会标准ASTME647—83的规定．采用紧凑拉伸CT试件对SS400钢及其焊接接头CT试件的疲劳裂纹扩展速率进行了测试。发现：母材的疲劳裂纹扩展存在两个不同速率的阶段,焊缝及热影响区的疲劳裂纹扩展速率均低于母材;热影响区的疲劳裂纹扩展速率介于焊缝与母材之间;焊接接头组织和性能的变化并未导致SS400钢疲劳性能的降低。