65Mn锯片用钢硬度不均原因分析

采用硬度计、光学显微镜、SEM扫描电镜及EDS能谱分析,对65Mn锯片用钢生产中出现的硬度不均的成因及其影响因素进行分析研究。结果表明:引起65Mn锯片用热轧带钢硬度不均的主要原因是热轧钢板内珠光体片层间距不均匀、带状组织及脱碳层的存在;其中以珠光体片层间距不均为主,其特征为钢板内珠光体片间距大小不一,差别较大,珠光体组织的平直度较差。通过优化终轧后冷却工艺、炼钢及连铸工艺、加热制度等措施,有效改善了65Mn热轧钢板表面硬度均匀性。     

65Mn钢板淬火后硬度不均原因分析

针对65Mn钢圆锯片淬火后硬度不均现象进行了研究。对锯片的化学成分、原始组织及淬火后的组织和硬度进行了分析,结果表明,钢板化学成分满足标准要求,但存在明显的带状偏析,分析认为带状偏析是造成65Mn锯片淬火硬度不均匀的主要原因,同时提出了相应的改进措施。     

The Role of Internal Oxides on the Liquid Metal Embrittlement Cracking During Resistance Spot Welding of the Dual Phase Steel

Metallurgical and Materials Transactions A - One of the most effective ways to improve reactive wetting of dual phase (DP) steels during galvanizing process is annealing under relatively high...     

Dual Phase Heat Treatment of Low-Alloy Steel

Many researches on dual phase steel have beencarried out inthe past decades due to excellent prop-erties such as high work-hardening rate,highstrength and good ductility.Dual phase steels main-ly include three types of phase structure,ferrite-matensite,ma…     

低碳贝氏体复相钢相鉴别技术

普通金相侵蚀方法观察材料的显微组织虽然简洁快速,但往往只能显示晶界和相界,并且难以有效地区分多于两相的显微组织。特别是低碳贝氏体复相钢组织比较复杂,普通金相侵蚀方法很难满足需要,通过分析普通显微技术,彩色金相技术和电子背散射衍射技术,在各相定量分析方面进行了一些尝试和探索,并取得了一系列成果和进展。     

塔塔钢公司热轧双相钢的开发

采用低碳钢(C0.08%、Mn1.40%、Si0.50%和Nb0.022%)已开发出两种双相钢.采用Gleeble1500模拟器对其相变行为进行了研究.根据Gleeble的研究结果,选择了热轧参数.热轧带钢的性能符合DP350/600和DP400/700钢种的要求.DP400/700在YS/TS约为0.6时为铁素体 马氏体钢,而DP350/600在YS/TS＞0.8时为铁素体 贝氏体钢.应用透射电子显微技术确定了在铁素体 马氏体钢种中有马氏体存在.     

FB双相钢延伸凸缘性能与组织的关系

通过对比观察不同扩孔率双相钢的显微组织,研究了铁素体贝氏体双相钢的延伸凸缘性能与组织之间的关系。试验结果表明,当显微组织由多边形铁素体和粒状贝氏体组成时,FB双相钢能达到优异的延伸凸缘性。多边形铁素体有利于扩孔率的提高而下贝氏体和板条马氏体则有害;M-A的尺寸对延伸凸缘性影响很大,随着M-A岛尺寸的减小,扩孔率逐渐增大,当M-A岛的宽度为0.7μm时,FB双相钢的扩孔率能达到120%。     

Bake Hardening of Laser Welded Dual Phase Steel

The influence of bake hardening on the mechanical properties of laser welded dual phase steel was investigated. A remarkalbe increase of the hardness in the zone influenced by laser welding was observed. The fusion zone had a low carbon lath martensite microstructure. The laser weld region had a higher interstitial carbon content than the base material. The dual phase steel exhibited a clear bake hardening effect in both the as‐received and the laser‐welded conditions. The bake hardening effect is more pronounced in the prestrained laser welded condition. A pronounced decrease of the ductility was observed for prestrained laser welded DP steel.     

Improvement of Quench Factor Analysis in Phase and Hardness Prediction of a Quenched Steel

The accurate prediction of alloys’ properties introduced by heat treatment has been considered by many researchers. The advantages of such predictions are reduction of test trails and materials’ consumption as well as time and energy saving. One of the most important methods to predict hardness in quenched steel parts is Quench Factor Analysis (QFA). Classical QFA is based on the Johnson–Mehl–Avrami-Kolmogorov (JMAK) equation. In this study, a modified form of the QFA based on the work by Rometsch et al. is compared with the classical QFA, and they are applied to prediction of hardness of steels. For this purpose, samples of CK60 steel were utilized as raw material. They were austenitized at 1103 K (830 °C). After quenching in different environments, they were cut and their hardness was determined. In addition, the hardness values of the samples were fitted using the classical and modified equations for the quench factor analysis and the results were compared. Results showed a significant improvement in fitted values of the hardness and proved the higher efficiency of the new method.     

低碳微合金双相钢沉淀相粒子的分析

采用萃取复型技术研究了实验室Φ450轧机控轧控冷后铁素体-马氏体双相钢(%:0.08C、0.22Si、1.02Mn、0.02Nb、0.013Ti、0.034Al)中沉淀相粒子。结果表明,该钢在1200℃时就存在尺寸为几十纳米的(Nb,Ti) (CN),经X-射线能谱分析得出,小颗粒中Nb含量大于Ti含量,形状不规则,大颗粒沉淀相主要含Ti,Nb含量较少,呈长方形;经控轧控冷后(Nb,Ti)(CN)为间隙析出,且主要在晶界处析出。     

高强度热镀锌双相钢的可镀性问题研究

 高强度热镀锌双相钢的可镀性问题是当前热镀锌技术的主要热点之一。生产高强热镀锌双相钢的主要难点在于得到理想的组织与可镀性之间的矛盾。国内外研究机构深入研究了高强度双相钢中的合金元素的选择性氧化行为、氧化物的生长规律,以及在退火炉气氛下气相-金属反应。在工业实践上应用这些基本的理论与规律,开发出了多种可提高高强度热镀锌双相钢可镀性的工艺,包括预氧化-还原法、反应退火法、闪镀法等。     

Temper-Aging of Continuously Annealed Low Carbon Dual Phase Steel

The temper-aging response of a 0.05 pct C plain carbon dual phase steel was studied in order to understand the metallurgical aspects of the overaging cycle of a continuous annealing process. Four regimes can be distinguished during the isochronal temper-aging depending upon the temperature. Below 225 °C (regime I), the yield strength and yield point elongation(YPE) increase with temperature while the tensile strength changes insignificantly. In regime II (~225 to 350 °C), both the yield and tensile strength decrease rapidly with temperature whileYPE remains constant. In regime III (~350 to 535 °C), the tensile strength continually decreases with temperature but yield strength shows either a plateau or peak. TheYPE rises again with temperature in this stage. Above 535 °C (regime IV), the yield and tensile strength andYPE all drop again with temperature. The isothermal temper-aging behavior was also studied and it is found that at room temperature both yield and tensile strength increase with time. At higher temperatures, however, the tensile strength decreases with time but yield strength increases initially then drops with time. The change of properties during the isochronal and isothermal temper-aging is explained in terms of the microstructural changes in ferrite and martensite.     

高强度船板在两相区的正火

高强度船板第一次正火后力学性能不合格，又在两相区加热进行不完全奥氏体化正火试验，产生了细粒状贝茵体组织，使高强度船板力学性能满足了标准的要求。     

Fe-C-Mn双相钢奥氏体形成动力学

本文采用OM及SEM金相定量研究了亚临界(低于A_C1)退火对冷轧态Fe-c-Mn双相钢临界区(A_C1~A_C3)奥氏体形成动力学的影响,采用STEM能谱分析及SEM波谱分析测定了在亚临界退火过程中碳化物中锰浓度的变化及在临界区形成的奥氏体的锰浓度。实验结果表明,亚临界退火过程发生锰向碳化物中的平衡偏聚,从而使临界区形成的奥氏体具有较高的锰含量,提高奥氏体的淬透性。这对于周期退火双相钢板的生产具有重要意义。     

Effect of Strengthening Phase on Deformation Behaviour during Uniaxial Tension of Hot-rolled Dual Phase Steel

Two kinds of C-Si-Mn-Cr series tested steels were designed to obtain dual phase microstructures of ferrite （F） ＋martcnsite （M） or ferrite （F）-bainite （B） with different mechanical properties. Effects of strengthening phase on yielding and fracture behaviours during uniaxial tension of dual phase steel were discussed. Compared with hot-rolled martensite dual phase steel, ferrite-bainite dual phase steel has high ratio of yield strength to tensile strength （YS/TS） and low elongation. During necking process of uniaxial tension, microvoids of ferrite-martensite steel are generated by fracture of ferrite/martensite boundary or martensite islands with irregular shape. But ferrite matrix elongated remarkably along deformation direction, and strengthening phase also coordinated with ferrite matrix. Compatible de formation between ferrite and bainite is distinct. Ferrite-bainite dual phase steel has fine and less microvoid, and phase boundary of ferrite and bainite is beneficial for restraining generation and extending of microvoid.     

关键退火参数对590MPa级热镀锌双相钢力学性能的影响

 采用多功能退火模拟器,按照首钢1号CGL(连续镀锌生产线)配置研究了带速、加热温度及快冷终止温度对590MPa级热镀锌双相钢力学性能的影响。研究结果表明,提高带速可以提高冷却速度和减少带钢在均衡段停留时间,有利于保证双相钢的性能。要获得良好性能的双相钢,大于90m/min的带速是必要的。加热温度过低会导致双相钢强度不足,过高则会导致伸长率和硬化指数降低。800℃的加热温度可以获得较好的双相钢综合力学性能。快冷终止温度升高,双相钢的抗拉强度和加工硬化指数都显著降低。在均衡段电加热有能力保证镀锌温度的情况下,降低快冷终止温度有利于获得良好的双相钢力学性能。     

感应热处理双相钢的微观组织

采用感应热处理两次淬火工艺对硅锰系低碳钢进行双相热处理,得到具有感应热处理双相组织特征的双相钢。研究表明,感应热处理两次淬火的双相组织中铁素体晶粒细化,马氏体呈细层片状分布,使双相钢的强韧化水平明显提高。证明感应热处理两次淬火是一种制取高性能双相钢的新型工艺。     

冷轧双相钢DP800生产工艺及性能研究

探讨了800 MPa级冷轧双相钢的成分体系、冷却处理工艺、组织及性能;研究了退火温度、冷却速率对双相钢性能的影响,分析了双相钢的强化机理,并且优化了退火工艺参数。结果表明,冶炼过程采用C-Si-Mn-Cr-V成分体系,轧制过程采用650℃±20℃的中温卷取,连续退火过程中快冷段投入高氢(H2含量20%)冷却,冷速达到42~50℃/s,能够得到由铁素体和马氏体组成的冷轧双相钢DP800,综合力学性能优良。