高强度低合金钢焊缝金属的组织及其影响因素

HSLA钢焊缝金属组织主要是由先共析铁素体、侧板条铁素体和针状铁素体组成,针状铁素体具有良好的韧性和强度配比,是HSLA钢焊缝金属最希望得到的组织。从合金元素、焊接参数和夹杂物三个方面对针状铁素体组织的形成进行阐述,以期为HSLA钢的使用及配套焊丝的开发等相关研究提供一定的借鉴。     

HSLA钢冶金工艺技术的进展

20世纪90年代以来,薄板坯连铸连轧技术及中厚板坯炉卷轧制工艺,进入了低合金高强度钢(HSLA)的生产流程;并在该流程中对HSLA钢热机械控制轧制工艺(TMCP)取得了不少有益的经验。目前薄板坯连铸连轧CSP(Compact Strip Production)工艺所开发的钢种有:(1)ECC、UCC和IF软钢;(2)高强度多相DP和TRIP钢;(3)X80级管线钢。介绍了薄板坯连铸连轧和中厚板坯炉卷轧制工艺开发的HSLA钢品种的工艺特点和工艺优化。     

热连轧HSLA钢Q345B减量化生产实践

介绍了安钢1780 mm热连轧机组低合金高强度结构用钢(HSLA)Q345B的减量化生产,该减量化主要采用降低Mn含量,并添加适量的钛微合金元素、优化冶炼工艺、降低钢中N、S含量和优化轧制工艺等措施,降低生产成本,达到减量化生产的实践经验。     

不同碳含量对HSLA钢的缺口敏感性的影响

通过对不同含碳量的HSLA钢平板试样进行静拉伸实验宏观结果分析、组织观察及断口观察分析,研究了不同含碳量的HSLA钢的缺口敏感性及断裂机制。结果表明:HSLA钢随着含碳量升高,缺口敏感性显著升高。由应力集中系数Kt计算缺口处的最大应力(Rmax)远大于抗拉强度(R),产生了"缺口强化"。经调质后,HSLA钢的组织为回火托氏体。宏观断口分析:光滑试样为具有明显放射区和剪切区的韧性断裂,缺口试样为具有"人字形"解理断口。微观断口分析:光滑试样断口为韧窝,缺口试样为准解理和舌状花样断口。     

低合金钢在中国的发展现状与趋势

 在过去的几十年里,品种结构调整一直是中国钢铁工业的重要任务。伴随中国钢铁产量的快速增长,在高强度低合金钢（HSLA）技术领域取得了一系列研究成果,并在实际品种开发中获得了成功的应用,如细晶/超细晶粒钢技术、微合金钢的析出相控制技术等。“十二五”期间国内外装备制造业的发展为中国钢铁工业产品结构调整带来了机遇和挑战。通过使用性能更优、用量更少的HSLA钢,可大量节约钢材消耗,减轻对资源、能源、环境的压力。毫无疑问,积极推进HSLA钢的应用是实现中国钢铁工业可持续发展的必由之路。     

HSLA钢促进铌的需求增长

铌应用于生产高压气体管路、船舶、货车大梁及小汽车的HSLA钢(高强度低合金钢)以增加其强度,由于HSLA钢的生产继续上升,铌的需求在80年代中可望以每年平均增加10%的速率增长。     

文献简介

改善钢的强度和韧性主要是为了扩大结构钢的应用。然而强度和韧性彼此之间又是矛盾的。只有细化铁素体晶粒才对钢的强度和韧性二者均有贡献。热机械加工,特别是控轧和加速冷却而产生的细化铁素体晶粒对HSLA钢提供了强度和韧性二方面的效果。因此,控制轧制和加速冷却技术已被广泛地应用于HSLA钢的强化和韧化的工艺中。     

关于薄板坯连铸连轧产品开发问题的探讨

分析了国内外薄板坯连铸连轧产品开发现状及发展趋势,探讨了转炉薄板坯连铸连轧生产HSLC钢的优势,薄板坯连铸连轧HSLA钢微合金元素的控制,薄规格及超薄规格热带产品开发,薄板坯连铸连轧生产冷轧用钢板的技术分析,薄板坯连铸连轧生产高性能、高附加值产品的技术探讨以及薄板坯连铸连轧产品开发的关键工艺技术等.     

舰船用钢向高强度化方向发展

<正>为了满足大型水面舰船和大潜深潜艇的需求,舰船用钢需向高强度化方向发展。美国航母大量采用690MPa级高强钢作为航母甲板用钢,新近又研发了强度级别785MPa级的HSLA115钢,并已在最新航母福特号上试用。为满足大潜深潜艇(500~600m)的建造要求,俄、     

热装板坯中微合金元素析出行为研究

正低合金高强度(HSLA)钢用途广泛,涵盖建筑结构、汽车和管线行业。它们由于加入少量合金元素如铌、钒和钛而称为HSLA钢,典型碳含量小于0.1%。合金加入量通常不到0.1%,从而被称作微合金化。微合金化元素通过碳化物、氮化物和碳氮化物的析出,改善HSLA钢的力学性能。析出物尺寸、分布、析出分数及析出物类型都是决定钢的使用性能的重要因素。析出物延迟和/或阻止奥氏体再结晶并在最终基体中产生析出强化,在热轧过程中,     

HSLA钢板控轧控冷生产中组织性能的预测模型

建立了ＨＳＬＡ钢板在控制轧制和控制冷却生产中,组织演变和力学性能的预测模型。模型包括再结晶,析出,相变和力学性能四个子模型,分别考虑了发生在控轧控冷过程中的各种冶金学现象。模型的计算结果与两种Ｎｂ－Ｔｉ－Ｖ钢的控轧控冷实验所测得的结果比较一致。     

冷却速度对高强度低合金钢组织和性能的影响

采用热模拟试验机、拉伸试验机以及光学显微镜等设备,根据CCT曲线和拉伸实验的结果,研究了冷却速度对700MPa级超级钢组织和性能的影响。在实验室热轧实验的基础上,比较了500MPa和700MPa两个强度级别HSLA钢的组织和性能随冷却速度的变化情况。结果表明,冷却速度对两种钢的影响不同：冷却速度增大时,500MPa级钢的晶粒明显变细,而700MPa级钢的晶粒尺寸变化不大。     

Microstructural model for hot strip rolling of high-strength low-alloy steels

The microstructural evolution during hot-strip rolling has been investigated in four commercial high-strength low-alloy (HSLA) steels and compared to that of a plain, low-carbon steel. The recrystallization rates decrease as the Nb microalloying content increases, leading to an increased potential to accumulate retained strain during the final rolling passes. The final microstructure and properties of the hot band primarily depend on the austenite decomposition and precipitation during run-out table cooling and coiling. A combined transformation-ferrite-grain-size model, which was developed for plain, low-carbon steels, can be applied to HSLA steels with some minor modifications. The effect of rolling under no-recrystallization conditions (controlled rolling) on the transformation kinetics and ferrite grain refinement has been evaluated for the Nb-containing steels. Precipitation of carbides, nitrides, and/or carbonitrides takes place primarily during coiling, and particle coarsening controls the associated strengthening effect. The microstructural model has been verified by comparison to structures produced in industrial coil samples.     

Precipitation hardening of HSLA steels

A process model to describe the strength contribution from precipitation hardening during coiling after hot rolling has been developed for V and Nb HSLA steels. Experimental measurements of ageing behaviour on the V steel were conducted on coil material which was received in an underaged condition. The size and composition of precipitates was examined on replicas using scanning transmission electron microscopy. The precipitates were observed to be V rich and a substantial increase in precipitate size occurred as a function of ageing time. The modelling approach developed by Shercliff and Ashby for aluminium alloys was extended to microalloyed steels. The model assumes particle coarsening is the rate controlling process and that the precipitates are initially sheared by dislocations with a transition to non-shearable precipitates at peak strength. After calibration of the model, good agreement was observed between the model predictions and experimental data. A model for ageing in a Nb HSLA steel was also developed using literature values for the ageing behaviour.     

Recent Development and Applications of V Microalloying Technology in China

This paper reviews recent developments of V microalloying technology and its applications in HSLA steels.Enhanced-nitrogen in V-containing steel promotes precipitation of fine V(C,N) particles,and improves markedly precipitation strengthening effectiveness of vanadium,therefore,there is a significant saving of V addition in the same strength requirement.Vanadium can be used effectively for ferrite grain refinement by the nucleation of intragranular ferrite promoted by VN precipitates in Austenite.The combination of intragranular ferrite (IGF) on VN particles and the recrystallization controlled rolling (RCR) technology realize the grain refinement in V-containing steel.V-N process is a cost-effective way for high strength rebars,forging steels and thin slab direct rolling strips.     

Recrystallization controlled rolling and accelerated cooling for high strength and toughness in V-Ti-N steels

Optimum thermomechanically controlled process parameters have been established for the production of Ti-V-N microalloyed high-strength low-alloy (HSLA) steels. On the basis of laboratory simulation and full-scale processing, it has been shown that nitrogen is an essential alloying element addition and full appreciation of its effects leads to the ability to utilize high nitrogen steel in connection with hot rolling in a high-temperature regime to produce HSLA products with very favorable combinations of yield strength and toughness. The effects of reheating temperature, rolling reduction, cooling rate, and finish-cooling temperature (FCT) on the ferrite grain size and mechanical properties have been examined. It has been shown that the potential for precipitation strengthening is dependent on vanadium, nitrogen, and cooling parameters. Accelerated cooling (ACC) prevents precipitation of vanadium nitrides in austenite and enhances both grain refinement and precipitation strengthening. By adjusting nitrogen content and processing parameters, a yield strength of 500 MPa and impact transition temperature (ITT) below -60 ‡C can be obtained in the as-hot-rolled condition in Ti-V-N steels, using high finish-temperature hot rolling and accelerated cooling.     

钒微合金化钢的技术进展与应用

摘要：介绍了钒微合金化技术的最新进展以及钒钢的开发与应用情况。氮是含钒钢中有效的合金元素,含钒钢中增氮,优化了钒在钢中的析出,显著提高沉淀强化效果。采用钒氮微合金化设计,配合适当的轧制工艺,促进V(C,N)在奥氏体中析出,起到了晶内铁素体形核核心作用,实现了含钒钢的晶粒细化。最新的研究成果表明钒微合金化可以提高双相钢、贝氏体钢、相变诱导塑性钢、孪晶诱导塑性钢、热成型马氏体钢等汽车用先进高强度钢的强度并改善使用性能,显示出良好的应用前景。钒氮微合金化技术在中国高强度钢筋、高强度型钢、非调质钢、薄板坯连铸连轧高强度带钢等产品中获得广泛应用,大大促进了中国钒微合金化钢的发展。     

Strain-aging of vanadium, niobium or titanium-strengthened high-strength low-alloy steels

Four commercially available high-strength low-alloy (HSLA) steels were evaluated in this study. It was determined that all four steels were susceptible to strain-aging by interstitial solutes. The increase in strength due to strain-aging was similar to that observed in a low carbon steel studied for comparison. At high levels of prestrain, the percent loss in ductility in the HSLA steels was comparable to that observed in the low-carbon steel in specimens prestrained to the same fraction of the total elongation of the as-received metal. However, when considered on an absolute basis, the residual ductility in the HSLA steels was 25 to 50 pct of that observed in the low-carbon steel. The kinetics of strain-aging were briefly examined. Indications are that the kinetics are slower in the HSLA steels than they are in the low-carbon steel.     

连铸坯热送热装生产工艺的实践

叙述了低合金高强度钢在中国钢铁工业继续发展中的作用，介绍了国外低合金高强度钢在产品、合金化和工艺设计方面的发展。