VN微合金化超细晶高强钢的组织性能研究

基于电炉薄板坯连铸连轧流程氮高的特点,采用VN微合金化的成分设计,通过炼钢、连铸、均热、轧制和冷却各工艺过程的控制研究,开发了VN微合金超细晶高强钢板。钢板屈服强度达到了550MPa级,铁素体晶粒尺寸达到了3．0～4．0μm,具有良好的韧性、冷成形性能和焊接性能,满足汽车、工程机械制造等行业的要求。     

1000MPa级Ti微合金化超细晶冷轧双相钢及其制备工艺

专利号：CN201010034472．0专利权人：北京科技大学本发明是一种1000MPa级Ti微合金化超细晶冷轧双相钢及其制备工艺,属于冷轧超高强汽车用钢技术领域。钢的化学成分质量分数为：C：0．03％～0．20％,Si：0．20％～0．80％,Mn：1．2％～2．0％,Ti：0．0300～0．15％,S％O．015％,P％0．020％,Als：0．02％～0．15％,余量为Fe。本发明以C-Si—Mn—Ti为基本合金系,采用价格低廉的Ti而不添加Cr、Mo、Nb、V等合金元素,降低了生产成本,     

钒微合金化的低合金高强钢

发展钒合金化的低合金高强度热轧钢权，符合我国的资源和人有良好的推广应用前景。合理进行万分微调和控制热轧工艺是提高钢板质量的重要措施。     

含钒超细晶双相钢的细化机制

利用铁素体+马氏体+贝氏体的初始显微组织结合冷轧和连续退火的方法达到了细化晶粒的目的,通过这种方式制备的双相钢中有63.8%的铁素体晶粒尺寸分布于0.5～1μm,有53%的马氏体晶粒尺寸分布于0.5～1μm.针对该现象研究了基于铁素体+马氏体+贝氏体初始显微组织含钒超细晶双相钢的晶粒细化机制.分析认为,细化机制主要有三个方面:第一是形变对显微组织的细化,包括为了得到铁素体+马氏体+贝氏体的初始显微组织而进行的热轧和冷轧;第二是冷轧态显微组织的再结晶和快速奥氏体化;第三是钒的析出物阻碍奥氏体的长大.     

09CuPCrNiMoNb微合金化热轧耐候双相钢

测定了09CuPCrNi经Mo和Mo、Nb微合金化的两种热轧耐候双相钢0．11C-0．27Cu-0．60Cr-0．20Ni-0．41Mo和0．07C-0．29Cu-0．53Cr-0．22Ni-0．42Mo-0．03Nb的连续冷却转变动力学(CCT)曲线。Mo微合金化钢CCT曲线中铁素体转变区与贝氏体转变区之间有60—80℃宽的奥氏体亚稳区；MoNb微合金化钢CCT曲线没有奥氏体亚稳区。这两种钢通过控轧控冷工艺均可获得铁素体 马氏体双相组织。     

钛钒微合金化钢中碳氮化物的鉴定与分析

微量钛和钒加入C-Mn钢和C-Mn-Si钢中能大幅度提高钢材的强韧性。这种效应与钛钒析出物的细化晶粒和沉淀强化作用有关,而且这种效应的强弱主要取决于析出物的形态和数量,因而析出物形态的鉴定与分析对研究此类钢是非常重要的。     

低碳钢中超细铁素体的长大倾向

在热模拟单向压缩条件下考察了四个不同C,Mn含量的低碳钢中通过形变强化相变产生的超细铁素体在模拟卷取温度下的长大倾向.结果表明,不同C,Mn含量的四种钢中的超细铁素体在-500℃的保温0～10min过程中都很稳定,没有明显的长大过程,也未明显观察到铁素体的静态再结晶.超细铁素体稳定的主要原因是由于稳定的第二组织（珠光体或渗碳体颗粒）的有效钉扎,它既阻止了铁素体的明显长大,也抑制其静态再结晶的充分进行.但不同C,Mn含量的四种钢中的第二组织有不同的演变规律,保温过程中形变奥氏体内形成离异珠光体并缓慢粗化.另外,利用背散射电子衍射取向成像技术还测定了08钢保温过程中的取向（差）变化.     

Modern Microalloyed Steels

The addition of microalloying elements (MAE) to low C-Mn-Si HSLA steels has led to many benefits to the producers,fabricators and end-users.Microstructural improvements such as microstructural refinement,higher dislocation and sub-grain boundary densities and finer M-A-C distributions have led to higher strength,improved toughness and better formability.These improvements can often be traced to the MA addition.In steels for load-bearing applications,the combination of MAE with hardenability additions (Cr,Mo,B,etc.) and lower transformation temperatures has led to much higher strength levels than what were available a few years ago.The resulting nonpolygonal,bainitic and martensitic ferrite microstructures have not only higher strengths but also adequate levels of improved ductility and toughness.Hot strip,plate and pipe applications have benefitted from these developments.Similar improvements have been found in the microalloyed forging steels,where the change from pearlite-ferrite to bainitic ferrite microstructures has led to higher strengths and improved high-cycle fatigue resistance,with little penalty in ductility and toughness.In the cold rolled gauges,both the so-called Advanced High Strength Steels (DP,TRIP and Complex Phase Steels) and the martensitic direct-quenched and press-quenched steels,along with the Interstitial-Free steels,have benefited from MAE additions,especially in the very popular zinc-coated sheet form.This paper will briefly review each of these topic areas,and the underlying physical metallurgy will be discussed.     

热轧双相钢DP600组织性能的研究

选择添加铬、钼合金元素的碳、锰、硅系的高强双相钢DP600为研究对象,选择Gleeble-3800热模拟试验机为研究方法测定了DP600动态CCT曲线,并模拟DP600双相钢热轧过程。采用金相组织观察、织构分析及力学性能测试等手段分析了不同工艺制度下双相钢组织及织构变化规律以及对性能的影响,从中获得最佳组织配比及优化的热轧工艺参数。根据优化的中试结果,进行了热轧双相钢DP600的工业试制。结果表明,试制样品的显微组织为铁素体及马氏体;屈强比均小于0.65,抗拉强度均在600 MPa以上;伸长率在24%以上;其拉伸曲线均为连续曲线,无屈服点伸长,具有典型的双相钢特征。     

Microstructure and Tensile Properties in Dual Phase and Trip Steels

Advanced high‐strength steels, like dual phase and TRIP steels, have gained much interest for automotive application. The complex microstructures in dual phase steels, and even more critical, the metastable microstructure in TRIP steels, do not follow the well‐established traditional microstructure‐property relationships for deep drawing steels. The volume fraction of the different phases, the phase distribution, and the stability of metastable phases influence significantly the forming potential. This paper discusses the correlation between different microstructural features and the mechanical properties. The tensile test properties of dual phase steels are governed by the martensite volume fraction, the martensite hardness and to a much smaller extent the martensite island diameter. Both in dual phase and more pronounced in TRIP steels the retained austenite content plays a vital role in determining the formability. The stability of the retained austenite can be described by different methods, it needs to be adjusted according to the forming temperature and the type and amount of strain. In general, multiphase steels require a very strict microstructure control in order to develop predictable forming behaviour.     

双相钢的巴克好森效应

本文总结了铁素体-马氏体双相钢在磁化过程中由于巴克好森跳跃所产生的巴克好森噪音和磁声发射信号的特征,以及材料的组织结构、应力、应变对信号的影响,探讨了巴克好森信号产生的机制以及与材料变形的内在联系。     

本钢超细晶粒钢的开发研制

介绍了本钢生产的几种超细晶钢的研制开发情况。在普碳钢成分的基础上开发出CX400和CX500高性能超细晶钢;在09CuPTiRE和SPA-H两种耐候钢的基础上开发出Cu-P-Ti-RE系和Cu-P-Cr-Ni系超细晶耐候钢。生产实践表明,几种超细晶钢的化学成分设计合理、热连轧生产工艺可行,晶粒明显细化,综合性能良好。产品成功应用于汽车结构件、铁道车辆和集装箱的制造。     

Influence of Martensite Distribution on the Mechanical Properties of Dual Phase Steels: Experiments and Simulation

The application of multiphase steels in the automotive industry has been rapidly increased according to economic, environmental and safety reasons. To determine an optimal combination of high strength and good formability of multiphase steels by using the FE modelling, their complex microstructures have to be considered. Two‐dimensional Representative Volume Elements (RVEs) were currently developed based on real microstructures for dual phase (DP) steels. In general, the microstructure of DP steels contains hard martensite particles and a soft ferritic matrix. The strain hardening behaviour of the individual phases was described in the model taking the microstructural constituents and the carbon partitioning during intercritical annealing into account. Two dual phase microstructures with same martensitecontent but different martensite distributions were investigated in experiment as well as in FEM simulation by means of the RVE. The resulting mechanical properties of these steels are strongly influenced by the phase distribution and interaction. As validation, calculated flow curves were compared with the experimental results from quasi‐static tensile tests. In addition, the local stress and strain partitioning between both phases depending on the spatial phase distribution and morphology is discussed.     

超细晶粒钢的生产工艺及发展概况

简要论述了超细晶粒钢的几种主要生产工艺以及国内外超细晶粒钢研究的发展情况。通过对各工艺的优缺点进行分析比较,认为将奥氏体晶粒超细化和后期相变控制有效结合起来的超细晶生产工艺具有良好效果。