控轧控冷工艺对高强度X100管线钢组织的影响

对一种X100管线钢进行热模拟试验,研究了过冷奥氏体的相变规律,提出了一种得到以粒状贝氏体+板条贝氏体为主的混合组织的控轧控冷工艺制度,分析了精轧变形量、冷却速度及终冷温度对实验钢微观组织的影响。结果表明,随着变形量的增大实验钢的微观组织逐渐细化,高强度的板条贝氏体含量减少而粒状贝氏体含量增多;随着冷却速度的增加和终冷温度的降低实验钢组织中的板条贝氏体含量明显提高,组织也逐渐细化;组织中板条贝氏体含量较高时实验钢具有较高的强度,但过多的板条贝氏体和针状M/A岛对材料的韧性造成不利的影响。     

低碳贝氏体钢的研究现状与发展前景

综述了低碳贝氏体钢的国内外研究现状,指出低碳贝氏体钢性能优良且成本低廉.并结合低碳贝氏体钢的市场需求和邯钢品种钢的研发方向,展望了低碳贝氏体钢的发展前景,提出低碳贝氏体钢产品品种的开发及其控轧控冷工艺的研制是其研究方向.     

DEVELOPMENT OF CONTROLLED ROLLED BAINITIC STEELS

本文简要回顾了低碳贝氏体钢的发展。介绍了国外近年来在超低碳控轧贝氏体钢的研究现状对我国控轧贝氏体钢的开发提出了一些看法。     

控轧贝氏体钢的发展

本文简要回顾了低碳贝氏体钢的发展。介绍了国外近年来在超低碳控轧贝氏体钢的研究现状对我国控轧贝氏体钢的开发提出了一些看法。     

控轧控冷技术对42CrMoA钢组织性能的影响

该文研究了不同规格42CrMoA钢热轧、轧后控冷与控轧控冷不同工艺条件下钢的金相组织、平均晶粒度与力学性能。研究结果表明不同规格的42CrMoA钢经过控轧控冷后可以有效抑制贝氏体的产生。控制进控制进轧机(KOCKS)的温度为(820±10)℃、上冷床温度(720±10)℃,其晶粒尺寸小于热轧和轧后控温的样品。经过控轧控冷工艺控制后,所有样品的硬度均小于260HB,达到免退火要求。有效地提高和改善棒材的组织和性能。     

超高强度55SiMn2Mo贝氏体钢组织和性能的研究

通过对５５ＳｉＭｎ２Ｍｏ贝氏体钢显微组织和力学性能的研究发现：该钢空冷条件下得到Ｂ／Ｍ复合组织，其中Ｍ为板条马氏体和孪日马氏体的混合组织，Ｂ为变态下贝氏体。５５ＳｉＭｎ２Ｍｏ钢空冷后在２５０－３００℃范围内回火时，可获得超高强度及较好的塑韧性配合，当回火温度超过３００℃后则有回火脆性产生。     

3CrMnMoVS塑料模具钢的微观组织研究EI

本文采用金相和透射电子显微镜对３ＣｒＭｎＭｏＶＳ塑料模具钢的微观组织进行了分析，实验结果表明，经正火处理的３ＣｒＭｎＭｏＶＳ钢的微观组织为形状不规则的铁基体上分布着许多粒状的组织，并有条状或纺锤状的硫化物存在。而粒状组织由上贝氏体、下贝氏体及马氏体组成，在部分铁素体中还存在部分尺寸在０．０５～０．１５μｍ　的Ｐｅ＿３Ｃ相。     

显微组织对65Mn钢中氢扩散的影响

用电化学渗透法分别研究了６５Ｍｎ钢五种不同组织对氢扩散系数和陷阱能的影响，结果表明，珠光体，球化珠光体，回火索氏体，下贝氏体，回火马氏体的陷阱能分别为１６．７１、３０．３２、３１．３５、３１．０１、３５．６１（ＫＪ／ｍｏｌ）。     

正火40MnMoV钎钢的贝氏体组织

用ＴＥＭ研究了新型钎钢４０ＭｎＭｏＶ的正火组织，发现它与Ｓｉ－Ｍｎ－Ｍｏ系的另一种钎钢５５ＳｉＭｎＭｏ相似，由无碳化物上，下贝氏体Ｂｕ、Ｂｌ、以孪晶马氏体为主的“块状组织”和约１５％残余奥氏体Ａｒ组成，但４０ＭｎＭｏＶ的Ｂｕ，Ｂｌ较多，Ａｒ和Ｌ则较少；Ｂｕ板条较粗大，其间分布着不连续的Ａ小片条；Ｂｌ片中有渗碳体与粤氏体Ａ共存；Ｌ的尺寸较小，硬度较低，讨论了该钢正火时贝氏体（Ｂ）相变的原因及影响贝氏     

轧制工艺对CSP生产低碳贝氏体高强钢组织和性能的影响

研究了CSP工艺生产低碳贝氏体高强钢的工艺控制与显微组织和力学性能的关系.通过比较不同终轧温度和卷取温度对低碳贝氏体高强钢组织性能的影响,得出钢板最终组织为不同比例的铁素体加贝氏体复相组织,且随着终轧温度和卷取温度尤其是卷取温度的降低,组织中贝氏体的体积分数增多,组织更加细小均匀,并且可以获得细小弥散的M-A组织和析出粒子,从而提高钢的屈服强度和韧性.     

变形制度对低碳锰钢组织性能的影响

为了获得细晶铁素体/贝氏体的复相组织,通过控轧控冷工艺研究了低碳锰钢在奥氏体区变形时变形量、终轧温度和卷取温度对组织演变和力学性能的影响规律.研究表明,增加变形量(对应道次间隔时间缩短)可以细化铁素体晶粒,但当终轧温度降低到800℃时,变形量的增加以及开冷温度的降低不利于贝氏体组织的获得.通过调整变形量、终轧温度、可开冷温度并适当降低卷取温度,可使实验钢获得晶粒尺寸约为5μm的铁素体和10%~20%的贝氏体组织,低碳锰钢强塑性能良好.     

高强度低屈强比铆螺钢轧制工艺的研究

为消除螺栓在热处理中产生的各种缺陷,缩短生产周期,使铆螺钢免热处理.采用热模拟试验机、实验室轧机和多工位冷镦机对铆螺钢轧制实验,铆螺钢原料和成品分别在拉力试验机和万能试验机上进行拉力试验,并对其组织进行了分析.结果表明,铆螺钢经过控轧控冷,获得具有多边形铁素体、细片状珠光体、粒状贝氏体、残余奥氏体和少量MA岛的多相组织.由于控轧控冷后的多相组织及TRIP效应,改善了螺栓的强韧性.铆螺钢因低的屈强比可以直接由热轧棒材冷镦成螺栓,螺栓无需最终热处理,产品的力学性能满足8.8级螺栓国家标准的相应要求.     

CSP流程生产低碳高强度汽车板组织性能的研究

研究了珠钢电炉CSP工艺生产低碳高强度钢板的热轧工艺与组织性能之间的关系,通过光学显微镜和力学性能试验等检测分析技术分析了控制轧制和冷却各阶段工艺参数对成品板显微组织和力学性能的影响.研究表明:降低终轧温度和卷取温度可有效细化晶粒,提高钢板的强度;采用适当的控轧控冷工艺制度,可以获得不同强度级别强韧性能良好的热轧低碳高强度汽车用钢板.     

Effect of controlled rolling/controlled cooling parameters on microstructure and mechanical properties of the novel pipeline steel

The study of controlled rolling/controlled cooling process parameters which affect the microstructure and mechanical properties of a novel pipeline steel has been optimized by the orthogonal experiment with four factors and three levels in this paper.However,the parameters of thermo-mechanical control process(TMCP)optimized by the Gleeble-3500 hot simulator could not satisfy performance requirements of the X100 pipeline steel.In order to improve the performance of this steel,the influence of finish cooling temperature(FCT) on the microstructure and property is studied in detail.It is found that,as this steel is thermo-mechanically treated by this set of parameters(the start heating temperature,finish rolling temperature(FRT),FCT and cooling rate of 1,180℃,810℃,350℃ and 35℃/s,respectively),the microstructures are mainly composed of granular bainite(GB)and acicular ferrite(AF).The effective grain sizes are below 20μm;the steel reaches the optimal balance between the strength and the toughness;the yield strength is 695 MPa;the tensile strength is 768 MPa;the elongation is 16.6%;the impact energy is 262 J at room temperature.All indexes could meet the requirements of X100 pipeline steel.     

Simulation of hot-rolled dual-phase weathering steel 09CuPCrNi

The continuous cooling transformation diagram of deformed austenite for steel 09CuPCrNi was constructed by means of a combined method of dilatometry and metallography. The diagram exhibits an elongated polygonal ferrite C-curve with a delayed pearlite start and a metastable austenite gap between the polygonal ferrite and pearlite regions and between the ferrite and bainite regions. For this experimental steel, it is possible to obtain a dual-phase microstructure directly by hot rolling and appropriate cooling. Based on the diagram, the technical process of a hot-rolled dual-phase treatment was established and simulated using a thermal simulation testing machine. Dual-phase microstructures were obtained that show some bainite phase and are characterized by an irregular distribution of island-shaped martensite in a matrix of equiaxed ferrite grains. The morphology of the martensite phase is essentially of the lath type, with small areas of micro-twins appearing.     

Influence of Hot Deformation and Subsequent Austempering on the Mechanical Properties of Hot Rolled Multiphase Steel

Influence of hot deformation and subsequent austempering on the mechanical properties of hot rolled multiphase steel was investigated. Thermo-mechanical control processing （TMCP） was conducted by using a laboratory hot rolling mill, where three different kinds of finishing rolling reduction, and austemperings with various isothermal holding duration were applied. The results have shown that a multiphase microstructure consisting of polygonal ferrite, granular bainite and larger amount of stabilized retained austenite can be obtained by controlled rolling processes. Mechanical properties increase with increasing the amount of deformation because of the stabilization of retained austenite. Ultimate tensile strength （σb）, total elongation （σ） and the product of ultimate tensile strength and total elongation （σb-σ） reach the maximum values （791 MPa, 36% and 28476 MPa%, respectively） at optimal processes.     

具有合理硬度梯度和组织分布的渗碳钢23CrNi3Mo的热处理冷却行为

利用Gleeble-1500热模拟机、光学显微镜(OM)、扫描电镜(SEM)以及透射电镜(TEM)对渗碳钢23CrNi3Mo的连续冷却相变规律以及等温转变规律进行了研究,并基于此,设计了一种新的热处理冷却工艺。研究结果表明,渗碳后试样以0.05℃/s和0.1℃/s的冷速连续冷却时,表面渗碳层为高碳马氏体组织,过渡区为高碳马氏体+下贝氏体的混合组织,基体为下贝氏体组织;渗碳试样外表面在高温段以较低的冷速(0.05~3℃/s)连续冷却时,碳化物沿晶界析出形成网状碳化物;无渗碳的实验钢的贝氏体等温转变温度范围为375~450℃。新的热处理冷却工艺为:试样在880℃保温完成后,采用快速冷却工艺,以冷速大于等于5℃/s进入贝氏体转变温度区,直接入450℃的盐浴炉,入炉后均温5~10min,在低温转变区即贝氏体转变温度区间,采用慢速冷却工艺,冷速小于等于0.1℃/s。获得的试样渗碳层深度为1.4mm,国外的阿特拉斯钎头渗碳层深度为1.2mm,两者基本相同,但前者硬度分布更加平缓;两者表面显微组织均为高碳马氏体组织,过渡区均为马氏体加下贝氏体组织,基体均为贝氏体组织。通过设计新的热处理冷却工艺,获得了与国外钎头相同水平的试样。     

3Cr2Mo塑料模具钢连续冷却相变行为

为了调节塑料模具钢3Cr2Mo的组织,以实现在线预硬化,使用Gleeble1500热模拟试验机、光学显微镜以及透射电子显微镜等研究3Cr2Mo钢变形及未变形奥氏体的连续冷却相变行为及相变组织.实验结果表明,3Cr2Mo钢奥氏体稳定性较高,在所研究的实验条件下,连续冷却过程中没有出现先共析铁素体和珠光体,而是发生贝氏体和马氏体相变.热变形使奥氏体发生了机械稳定化,贝氏体相变推迟到较低温度下才完成.随着冷却速度的降低,贝氏体的形态由常规板条状变成粒状,最终可获得粒状贝氏体组织.     

Effect of austenite microstructure and cooling rate on transformation characteristics in a low carbon Nb-V microalloyed steel

Deformation dilatometry has been used to simulate controlled hot rolling followed by cooling of a Nb-V low carbon steel, looking for conditions corresponding to wide austenite grain size distributions prior to transformation. Recrystallization and non-recrystallization deformation schedules were applied, followed by controlled cooling at rates from 0.1 °C/s to about 200 °C/s, and the corresponding continuous cooling transformation (CCT) diagrams were constructed. The resultant microstructures ranged from polygonal ferrite (PF) and pearlite (P) at slow cooling rates to bainitic ferrite (BF) accompanied by martensite (M) for fast cooling rates. Plastic deformation of the parent austenite accelerated both ferrite and bainite transformations, displacing the CCT curve to higher temperatures and shorter times. However, it was found that the accelerating effect of strain on bainite transformation weakened as the cooling rate diminished and the polygonal ferrite formation was enhanced. Moreover, it was found that plastic deformation had different effects on the refinement of the microstructure, depending on the cooling rate. An analysis of the microstructural heterogeneities that can impair toughness behavior has been done.