共查询到20条相似文献,搜索用时 62 毫秒
1.
Transformation-induced plasticity-aided steel [TRIP steel (0. 4C-1. 5Si-1. 5Mn)] was rolled at room temperature to different thickness reductions (0, 4%, 10%, 20%, 40%, and 60%). The mechanical properties, microstructure and austenite fractions of the rolled samples were measured by tensile test, electron back scattered diffraction (EBSD) and X-ray diffraction (XRD) for each rolling. The deformation behavior was studied based on the analysis of the mechanical properties and microstructure of steel after tensile deformation, aiming at understanding the effects of cold rolling reduction on the decay behavior of the austenite and the change of mechanical properties of the TRIP steels. It was found that increasing rolling reduction increases the yield stress gradually but decreases the total elongation significantly. It is very interesting that after 10% rolling reduction the yield stress is about 1000 MPa but still with 20% total elongation, which gives an excellent combination of yield strength and ductility. Based on the XRD results, it was revealed that in both rolling and tension the austenite volume fraction monotonically decayed with the increase of rolling strain, but the decaying rate is faster in tension than in rolling, which may be ascribed to the higher temperature in rolled specimens than in the tensioned ones during deformation. Experimental results and theoretical reasoning indicate that the decreasing trend of austenite volume fraction with strain can be formulated by a unique equation. 相似文献
2.
3.
实现厚规格精冲带钢的顺利卷取是精冲钢冷连轧生产工艺成功应用的关键。利用4辊可逆冷轧机进行轧制试验,在MMS-200热模拟试验机上测定精冲钢的应力-应变曲线,建立精冲钢冷轧终态变形抗力模型。针对1750mm冷连轧机组配置的卡罗塞尔卷取机,进行精冲带钢卷取过程的机理分析和卷取状态的受力分析,为精冲钢冷连轧极限厚度卷取能力的分析和计算提供理论支撑。在此基础上,完成了不同摩擦条件下多规格精冲钢冷连轧生产卷取机的极限厚度计算,并给出相应的安全卷取厚度窗口。该研究适合于工业生产实践,对精冲钢冷连轧生产工艺研究具有重要意义。 相似文献
4.
The effects of Nb addition,individually and in combination with Ti,were evaluated over a range of coiling temperatures.Coiling temperature influences the ratio of soluble and precipitated Nb in the hot rolled steel containing 0.08 % C and 2.2 % Mn.Nb bearing precipitates can co-precipitate on TiN and impact the microstructure and mechanical properties of the steel after annealing treatment.Microstructure characterization revealed that recovery and recrystallization processes preceded austenite formation.The effects of Nb on austenite formation in cold rolled steels during heating and isothermal holding and on austenite decomposition during subsequent cooling were investigated using dilatometry.The addition of Nb retarded ferrite recrystallization starting temperature,but had no significant effect on the starting temperature of austenite formation during heating.The Nb addition also accelerated austenite formation once the transformation started,and was beneficial for the formation of a finer and homogeneous microstructure. 相似文献
5.
6.
7.
Tyson W. Brown John G. Speer David K. Matlock Dennis M. Haezebrouck 《Metallurgical and Materials Transactions A》2011,42(12):3611-3619
The effects of variations in free nitrogen content on the microstructure and room-temperature tensile properties of laboratory
processed dual-phase (DP) sheet steels with a base composition (wt pct) of 0.1C-2.0Mn-0.2Mo-0.2Cr were evaluated. Systematic
variations in aluminum and nitrogen content along with coiling temperature were used to create a range of interstitial nitrogen
contents and microstructure variations after hot rolling. Two cold rolling reductions of 40 and 70 pct were applied before
intercritical annealing. Tensile properties show increasing strength and decreasing total elongation with increasing nitrogen
content. Increasing the coiling temperature and adding Al diminished the N effects, while increased cold reduction increased
tensile strength in some instances. Microstructural observations indicate an increase in martensite fraction with increased
prior cold reduction, while increased coiling temperature decreased the fraction of martensite. 相似文献
8.
9.
In order to investigate the effect of coiling temperature and alloying of phosphorus (P) on the formation of precipitates and recrystallization behaviour, initial samples of P‐free and P‐alloyed IF‐steels were prepared by coiling at 580 and 720°C. Variations of precipitates and textures after coiling, cold rolling and recrystallization annealing were studied by means of small angle neutron scattering (SANS), neutron texture measurements and TEM observations. Hardness measurements and microstructure observations disclose that both coiling temperature and alloying of P affect softening of cold rolled samples. Coiling at a lower temperature increases the number of fine precipitates smaller than 10 nm in the hot band. Upon recrystallization annealing, precipitates ranging in size from 10 to 50 nm increase at the expense of fine particles smaller than 10 nm. Recrystallization behaviours in cold rolled IF‐steel samples were discussed by tackling the distribution of precipitates and the amount of solute P atoms in solution. 相似文献
10.
介绍了热轧TRIP钢TMP(形变热处理)的精轧阶段(奥氏体未再结晶区变形)、输送台冷却(γ-α两相区的相变)和卷取阶段(贝氏体转变)热轧TRIP钢组织演变的影响因素;冷轧TRIP钢临界区(γ-α区)退火和贝氏体转变区等温处理时的组织演变及其演变过程中TRIP钢残余奥氏体中碳的富集的研究进展。 相似文献
11.
12.
13.
选取IF软钢为研究对象,考虑热轧边部温降的影响,对其热轧卷取温度进行调整试验,并对热轧基料与冷轧成品卷分别进行力学性能、金相组织的分析,研究热轧卷取温度对冷轧成品组织性能的影响。结果表明,卷取温度对IF钢屈服强度、抗拉强度无显著影响,伸长率随温度升高先升高后降低,r值在卷取温度为750 ℃时最高;卷取温度升高时,热轧基料边部出现混晶及组织不均匀现象,冷轧退火会加剧组织不均匀,造成IF钢边部混晶。研究结果对于揭示IF钢板生产工艺与性能之间的内在联系有重要意义,也对指导企业制定低耗高效的轧制工艺参数以获得性能优异的产品具有积极作用。 相似文献
14.
The ultrafine grained duplex steels were fabricated by austenite reverted transformation annealing of the medium manganese steels after quenching or cold rolling. The microstructures were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and X‐ray diffraction (XRD). The mechanical properties were determined by uniaxial tensile test. It was demonstrated that both the quenched and cold rolled structures were transformed into ultrafine grained duplex structures with large fractioned austenite by ART‐annealing. Long time annealing is essential to obtain the large fractioned austenite in quenched steel, but only short time annealing is needed to get large fractioned austenite in the cold rolled sheet. The mechanical examinations indicated that ART‐annealing results in the superhigh tensile elongation (>40%) and superhigh strength (1000 MPa) in quenched steels after long time annealing but in cold rolled steels after short time annealing. Based on the analysis on the work hardening behaviors of these ART‐annealed steels, the abnormal work hardening rate was presented and analyzed. The substantially enhanced ductility was attributed to the Lüders band propagation of the ferrite matrix and/or the TRIP effects of the large fractioned austenite. At last the dynamic phase natures of both fraction and stress was proposed to interpret the abnormal hardening behaviors and the “S” shaped stress–strain curves. 相似文献
15.
The increased recycling of scrap leads in conventional steels to an increased content of undesirable trace elements. When scrap is used for steel production, the influence of precipitate‐forming or solid solution hardening trace elements in particular on the process and use properties has to be taken into account. The influence exerted by the elements niobium, titanium, chromium and molybdenum has been studied on the example of unalloyed deep drawing steels which are mainly used for the manufacture of automobiles. The production process – beginning with continuous casting, through hot rolling, cold rolling down to annealing – was simulated experimentally in laboratory equipment, and in parallel with a continuous casting simulator, forming dilatometer and high temperature conductimeter. Light‐optical microscopy and the EBSP measurements were used to characterise the pertaining microstructures. The mechanical final characteristics were determined in tensile tests. The results relating to continuous casting illustrate the influence of trace elements on precipitation, cracking, hot ductility and the phase transition from austenite in ferrite. The work softening during the hot rolling depends on the nature and the precipitation state of the foreign elements. The interplay of coiling temperature, precipitation and annealing temperature influences the softening during the annealing after the cold rolling. It could be shown that a large part of this takes place during the recovery. The analysed trace elements influence the final characteristics via hardening and grain sizes. 相似文献
16.
In the so‐called ferritic rolling the finishing is shifted down into the temperature region of ferrite, which enables a production of thinner hot strips (compared to the conventional hot rolling in austenite) with a changed texture development. The present study is focused on the effect of the process parameters of such initial warm rolled hot strips on the texture formation and hence on the deep‐drawing quality of the final cold strips. A special attention is given to the transmission of the hot strip texture to the cold strip. The investigation was carried out on commercial IF‐ and ELC‐steels by a laboratory simulation with the hot deformation simulator Wumsi (rolling simulated by the plane strain compression test). It was possible to optimize cold rolling and subsequent annealing by means of the measurements of the texture development during the ferritic (warm) deformation as well as the parameters of the processing route of such special production of cold strips by means of the calculation of r‐values. If compared with the conventional processing route, a considerable improvement of deep‐drawability with a diminished earing is achievable especially with the IF‐steel. 相似文献
17.
研究304奥氏体不锈钢薄板的硬度随冷轧变形量的变化规律,为奥氏体不锈钢薄板工业生产提供指导。同时,采用金相显微镜、维氏硬度测量、X-射线衍射仪和透射电镜研究了不同变形量冷轧对304不锈钢显微组织和机械性能的影响。在室温对0.5mm厚退火板材进行冷轧,使冷轧变形量从10%增加到52%。结果表明,形变诱发马氏体相变是导致304不锈钢冷轧时产生加工硬化的主要原因,冷轧可以显著提高钢的强度和硬度。当冷轧变形至40%时,304不锈钢的维氏硬度是未变形时的2.2倍,屈服强度、抗拉强度分别增大到未变形时的4.2倍(880MPa)和1.8倍(1312MPa)。 相似文献
18.
TRIP‐assisted multiphase steels have been thoroughly studied in the cold‐rolled and annealed state. The effects of hot‐rolling conditions on these steels are much less studied even though these are of major importance for industrial practice. This study was carried out in order to understand the effect of the hot deformation of austenite on the tensile properties of TRIP‐assisted multiphase steels. Two different compositions and microstructures are investigated. The first one is a low‐carbon steel (mass content of 0.15 %) with a microstructure consisting of an intercritical ferritic matrix, bainite and retained austenite. The second one is a medium‐carbon steel (mass content of 0.4 %) that consists of bainite and retained austenite. Both steels were deformed to various strain levels below the non‐recrystallisation temperature of austenite. The medium carbon steel was deformed in the fully austenitic temperature range whereas the low‐carbon steel was deformed in the intercritical temperature range. In both cases, the prior hot deformation of austenite brings about a large enhancement of the work‐hardening capabilities. In the case of the medium‐carbon steel, this effect can be attributed to a much larger TRIP effect taking place during straining. In the case of the low‐carbon steel, the improvement of the work‐hardening behaviour was attributed to an Interaction between the martensitic transformation and the dislocations already present within the surrounding ferrite matrix. 相似文献
19.
通过成分工艺优化,在传统冷轧铁素体和马氏体双相钢DP780的显微组织上引入了一定体积分数的残余奥氏体,研究了冷轧退火工艺参数对双相钢DP780的显微组织和力学性能的影响。通过调整连续退火工艺来控制显微组织中一次铁素体、二次铁素体、马氏体、残余奥氏体的比例、尺寸、形貌、分布,同时获得了连退工艺参数-显微组织-力学性能的本质关系。结果表明,通过在传统冷轧铁素体和马氏体双相钢的组织上引入了体积分数为5%~7%的残余奥氏体,不仅可以获得[ReL/Rm≤0.5]的超低屈强比型冷轧DP780,也改善了成型性能。 相似文献