温热加工对TRIP型双相钢延伸凸缘性的影响

温热加工对ＴＲＩＰ型双相钢延伸凸缘性的影响［日］长坂明彦等１绪言在以提高轿车冲撞安全性及轻量化为目的而研制的高强度钢板中，有效地利用了残余奥氏体（γＲ）的相变诱发塑性（ＴＲＩＰ）的ＴＲＩＰ型双相钢板（ＴＤＰ钢板）具有特别优良的深冲性和延展性。现正在积...     

利用相变诱导塑性效果的下一代高强度薄钢板

概述了利用相变诱导塑性（ＴＲＩＰ）效果的下一代高强度薄钢板增加延伸率的机理，生产原理和实际生产线，生产的例子，成形性，焊接性和疲劳寿命，在实际生产线上试验了拉抗强度５９０～９８０Ｎ／ｍｍ＾２级的冷轧和热轧钢板，确认了超过过去开发钢的强度和延伸的组合，确认在了平面应平变附近显著优良的拉伸性，通过ＴＺＲ试验也说明了良好的深拉延性，深拉延性的改善是由于通过ＴＲＩＰ增加屈服点，因子冲孔肩部的变形是平面应变     

国外汽车用钢板开发新进展

综述了国外汽车板研究开发的新进展,重点介绍了板带热轧工艺中ＩＦ钢热轧卷取温度控制、铁素体区轧制、ＴＲＩＰ钢、ＢＨ钢、冷轧与退火工艺及钢板表面质量检测与控制等汽车板品种、质量研究开发的新成果。     

含残留奥氏体高强度钢板的使用特性

含残留奥氏体高强度钢板的使用特性［日］横井龙雄等１前言通过ＴＲＩＰ（高强度及高韧性）效应发现，含残留奥氏体钢板的加工性能明显地优于现有的组织强化钢和析出强化钢，其使用特性引起了人们的关注。人们迫切希望这种高强度钢板不仅能作为汽车轻量化用材，而且还能制...     

TRIP钢板的组织、性能与工艺控制

介绍了ＴＲＩＰ钢板的组织形成机理、影响因素、性能以及国内外近几年的研究、开发进展情况,为ＴＲＩＰ钢板的进一步研究、开发和应用提供依据     

汽车用薄钢板的开发

1　前　言对汽车燃料消耗更低、撞车保护更好的要求越来越强烈。为迎接挑战 ,日本汽车制造商正使用既有延性又有高强度的新一代薄钢板 ,例如诱导相变塑性钢 (ＴＲＩＰ)和双相钢 ,来开发超轻型车体。由于社会要求汽车燃料的效率更高、乘客的安全性更高且在汽车使用寿命结束时 ,能在对环境影响较低的情况下对汽车回收再利用 ,钢铁工业正通过不断研究性能更高的钢材及模拟技术来满足汽车工业的需求。这些材料和技术在调试阶段不需要高费用的模型机来检验 ,就能表明钢的性能。汽车用薄钢板主要有三个方面 ,即外板、内板和车架 ,另外还有发动机等…     

合钢3#高炉监控系统

介绍了合钢３＃高炉监控系统基于ＰＬＣ、ＳＩＮＥＣＬ２网ＩＰＣ的硬件结构和软件功能，阐述了控制策略，显示策略，网络联结的实现谅记叙运行可靠，对国内同类型高炉具有通用性。     

经形变热处理高强焊接钢的合金化和性能

经形变热处理高强焊接钢的合金化和性能ＡＬＬＯＹＩＮＧＡＮＤＰＲＯＰＥＲＴＩＥＳＯＦＨＩＧＨ—ＳＴＲＥＮＧＴＨＷＥＬＤＩＮＧＳＴＥＥＬＨＥＡＴ—ＴＲＥＡＴＥＤＦＯＲＦＯＲＭＩＮＧ当前，高强度的厚板焊接钢（屈服极限大于５９０Ｎ／ｍｍ２），主要是用包括热轧...     

二次精设备对钢中气体的影响

１９８５年至今，宝钢引进ＲＨ，ＫＳＴ，ＣＡＳ和ＫＩＰ等钢水二次精炼设备都已相继投产，这对提高钢质，扩大品种发挥了重要作用。本文根据我们大量的取样分析，叙述３００ｔ转炉吹炼钢包钢水中气体状况，比较ＲＨ，ＫＳＴ，ＣＡＳ处理钢的气体变化规律及其主要影响因素。     

二次精炼设备对钢中气体的影响

１９８５年至今，宝钢引进的ＲＨ、ＫＳＴ、ＣＡＳ和ＫＩＰ等钢水二次精炼设备都已相继投产，这对提高钢质、扩大品种发挥了重要作用。本文根据我们大量的取样分析，叙述３００ｔ转炉吹炼钢包钢水中气体状况，比较ＲＨ、ＫＳＴ、ＣＡＳ处理钢的气体变化规律及其主要影响因素     

Effect of preforming on the formability of TRIP steel sheet forming processes

In this study,the formability of transformation-induced plasticity (TRIP) steel is studied during deep-drawing processes with preforming.The effects of preforming on theminimum thickness of can are investigated with a constitutive model accompanying strain-induced martensite transformation in prestrain condition.The constitutive model has been implemented into ABAQUS/UMAT for analysis of TRIP steel-forming processes.The results show that preforming slightly influences the thickness uniformity of TRIP steel in forming.     

Evaluation of the Static Stress‐Strain Behaviour of Phosphorus Alloyed and Titanium Micro‐alloyed TRIP Steels

A considerable research effort has been done in the field of cold rolled TRIP steels submitted to a two‐step annealing cycle. After annealing, these steels contain retained austenite, which offers them superior mechanical properties required for specific applications in automotive industry. In the present work, a physically based microstructural model has been applied to describe the static stress‐strain behaviour of phosphorus alloyed TRIP steel. The impact of the TiC precipitation on the static stress‐strain behaviour for a Ti micro‐alloyed TRIP steel was simulated. The model calculations were compared with experimental stress‐strain curves. An excellent agreement between simulation and experimental data was demonstrated.     

Study on the Corrosion Resistance of Multiphase TRIP Steels

Multiphase TRIP (Transformation Induced Plasticity) steels are known to combine higher strength with higher ductility.In this paper,the corrosion resistance of this steel has been has been investigated by accelerated corrosion tests,such as wet/dry cyclic corrosion and the weight loss in laboratory.The morphologies of their rust layers were observed by using scanning electron microscopy,and the corrosion performance of these steels was discussed by analyzing the protective mechanism.The results show that the corrosion rate of steel A is significantly greater than that of steels B and C in wet/dry cyclic corrosion and weight loss tests.The corrosion performance of conventional C-Mn-Si TRIP steel is deteriorated in both NaHSO 3 and 3.5 wt.% NaCl aqueous solutions.And superior corrosion performance is exhibited for TRIP steel with low alloying contents due to its high thermodynamic stability.The enhancement of corrosion performance of TRIP steel is attributed to the additions of alloying elements,such as Al,Cu,Cr,Mo,Ni,etc.The alloying elements increase the compactness of rust layers,so electrochemical characteristic of TRIP steel is improved.     

Finite Element Simulation of Mechanical Behavior of TRIP800 Steel Under Different Loading Conditions Using an Advanced Microstructure-Based Model

The mechanical behavior of a low alloy multiphase TRIP steel has been predicted by an advanced microstructure-based finite element method. A representative volume element chosen based on the actual microstructure has been utilized for simulating the mechanical behavior of the studied steel. The parameters describing the martensitic transformation kinetics have been estimated using both crystallographic and thermodynamic theories of martensitic transformation. The mechanical behavior of each of the constituent phases required for the prediction of mechanical behavior of the studied material has been extracted from those reported in the literature. Comparison of the predicted mechanical behavior of the investigated TRIP800 steel with those reported in the literature shows that there is good agreement between simulated and experimental results. Therefore, it can be said that, the utilized microstructure-based model can be used for the prediction of both mechanical and transformation behaviors of the TRIP800 steels. It is worth noting that all of the parameters used in the model, except the sensitivity of the martensitic transformation to the stress state, can be estimated theoretically; thus, the number of parameters obtained by correlating the simulated and experimental results reduces to one. This is the unique characteristic of the utilized model, which makes the application of the model for simulation of the mechanical behavior of TRIP steels simpler than that of the similar ones.

     

Effect of Bake‐Hardening on the Structure‐Property Relationship of Multiphase Steels for the Automotive Industry

The effect of a bake‐hardening (BH) treatment on the microstructure and mechanical properties has been studied in C‐Mn‐Si TRansformation Induced Plasticity (TRIP) and Dual Phase (DP) steels after: (i) thermomechanical processing (TMP) and (ii) intercritical annealing (IA). The steels were characterized using X‐ray diffraction, transmission electron microscopy (TEM) and three‐dimensional atom probe tomography (APT). All steels showed high BH response. However, the DP and TRIP steels after IA/BH showed the appearance of upper and lower yield points, while the stress‐strain behavior of the TRIP steel after TMP/BH was still continuous. This was due to the higher volume fraction of bainite and more stable retained austenite in the TMP/BH steel, the formation of plastic deformation zones with high dislocation density around the “as‐quenched” martensite and “TRIP” martensite in the IA/BH DP steel and IA/BH TRIP steel, respectively.     

Properties and application of TRIP‐steel in sheet metal forming

A further development of dual‐phase‐steels are represented by TRIP (transformation induced plasticity) ‐steels. TRIP‐steels contain austenite, which is metastable at room temperature. It transforms to martensite during straining (TRIP effect). This process improves the strength‐ductility balance of these steels. Two types of TRIP‐steels, low alloyed (L‐TRIP) and high alloyed (H‐TRIP), can be applied in sheet forming processes and exhibit different forming characteristics. Basing on results of uniaxial tensile tests and the evaluation of Young's modulus the forming limits in deep drawing processes and the component properties of deep drawn parts are discussed. The Young's modulus decreases significantly with increasing pre‐strain, especially demonstrated for the L‐TRIP material TRIP700. Forming limit curves determined at different forming temperatures indicate its influence on the forming limits. Martensite transformation is suppressed at a temperature of approximately T = 200 °C and therefore the major strain ?₁ decreases significantly. For the investigated stainless steel AISI304 (H‐TRIP) different lubricant types in comparison to chlorinated paraffins have been tested. Lubricants consisting of sulphur additives led to good forming conditions in forming processes, even better than lubricants based on chlorinated paraffins. The evaluation of component properties, compared between L‐TRIP and H‐TRIP, was done based on the analysis of springback and dent resistance. The L‐TRIP material TRIP700 shows higher springback angles than AISI304 resulting from higher yield strength and decreased Young's modulus, resulting from the forming process. The dent resistance of TRIP‐steel was exemplarily demonstrated for AISI304. Uniaxial pre‐strained sheet specimen were analysed to show the dent resistance depending on dent depth. During elastic denting pre‐strain has no influence on dent resistance. Further increasing dent depth lead to increased dent forces for pre‐strained specimens.     

连续退火的无Si TRIP钢的组织和力学性能

在实验室用Gleeble3500热模拟试验机制备了一种无Si TRIP钢.利用拉伸试验机、扫描电镜、透射电镜、X射线衍射以及热膨胀仪对其力学性能、微观组织和相变规律进行研究,在此基础上分析了贝氏体相变温度和时间对力学性能和残余奥氏体的影响.无Si TRIP钢呈现出良好的整体力学性能,抗拉强度分布在740~810 MPa,延伸率均在25%以上,最高可达32%以上;贝氏体等温温度为420℃时能获得最佳的综合力学性能,抗拉强度随贝氏体相变时间增加而下降,延伸率随之上升,而屈服强度没有显著变化.无Si TRIP制的铁素体晶粒大小约为3~4μm,比含Si TRIP钢铁素体晶粒细小;残余奥氏体的体积分数在8%~10%,比含Si TRIP钢低约3%;420℃保温300 s后贝氏体相变基本结束,而碳的扩散仍然在进行;无Si TRIP钢贝氏体相变速率比含Si TRIP钢快,贝氏体相变总量也更多.      

合金元素和工艺参数对热轧TRIP钢动态相变的影响

利用Gleeble热模拟试验机进行单轴压缩试验,研究了C-Mn-Si TRIP钢和C-Mn-Al-Si TRIP钢过冷奥氏体形变过程的组织演变,分析了合金元素和工艺参数对过冷奥氏体动态相变的影响.与等温相变相比,C-Mn-Si钢和C-MnAl-Si钢动态相变动力学明显加快.与C-Mn-Si钢相比,用质量分数约1%的Al替代Si后,C-Mn-Al-Si钢的A₃温度明显提高,在相同变形工艺条件下C-Mn-Al-Si钢过冷奥氏体动态相变较易发生,而C-Mn-Si钢动态相变得到的铁素体晶粒比较细小.减小动态相变前奥氏体晶粒尺寸,有利于过冷奥氏体动态相变的进行.提高过冷奥氏体形变时的变形温度或应变速率均对动态相变产生一定的阻碍作用,但影响不显著.      

Stress-assisted isothermal martensitic transformation: Application to TRIP steels

Low-temperature plastic flow in TRIP steels has been found to be controlled by stress-assisted isothermal martensitic transformation. For these conditions, the thermodynamics and kinetic theory of martensitic transformations leads directly to constitutive relations predicting the dependence of flow stress on temperature, strain, strain-rate, and stress-state, consistent with the observed behavior of TRIP steels. Guidelines are obtained for the control of temperature sensitivity, σ -ɛ curve shape, and stress-state effects to achieve novel mechanical properties.     

Sheet metal forming behaviour and mechanical properties of TRIP steels

Recently various kinds of high-strength sheet steels have been developed to meet the requirements of the automotive industry such as passive safety, weight reduction and saving energy. Usually the main problem of high-strength steels is their inferior ductility. Multiphase steels however show a very good combination of strength and formability so that the applicable region of high-strength steels has been widely enlarged. Multiphase steels have been developed for various purposes because of their ability to tailor properties by adjusting the type, the amount, and the distribution of different phases. Especially new developed triple-phase steels which make use of the TRIP effect (transformation induced plasticity) can further improve formability as well as strength due to the transformation of retained austenite to martensite during the deformation. In this work the transformation behaviour and the mechanical properties of low alloyed TRIP steels were investigated. The influence of the annealing parameters on transformation behaviour and on the amount of retained austenite were determined. In addition the temperature dependence of the mechanical properties and the effect of testing speed on the formability were studied. The investigation was carried out on seven different TRIP steels with different chemical compositions, especially the influence of the microalloying element niobium was considered. For reasons of comparison various mild and high-strength steels were tested parallel to the TRIP steels. It was found that the investigated TRIP steels offer very attractive combinations of elongation and strength values. An interesting temperature dependence of the mechanical properties can be observed, in such a way that the elongation values of the TRIP steels possess a maximum between +50 and +100°C. Due to its effect on grain size and on precipitation behaviour the addition of niobium leads to higher strength values without a strong decrease in ductility. In general, the mechanical properties are strongly affected by the type and the distribution of the different phases. The most important parameters, however, to influence the mechanical behaviour are the amount and the stability of the retained austenite, which are mainly controlled by the heat treatment and the chemical composition.