变形条件和冷却速率对低碳含Nb钢的相变及纳米析出的影响

利用Gleeble 3800热模拟试验机,研究了奥氏体再结晶和未再结晶组织对低碳含Nb钢连续冷却转变行为的影响,并对不同变形温度及冷却速率下Nb(C, N)的纳米析出行为进行了研究。结果表明,未再结晶区奥氏体的变形能够为多边形铁素体提供更多的相变形核点,扩大铁素体相变区,并且能够细化铁素体晶粒;相比于再结晶区1050℃单道次变形,未再结晶区的第二道次变形能够促进Nb(C, N)的析出,其中910℃变形时Nb(C, N)的析出量最多,850℃次之;冷却速率的增大能够抑制Nb(C, N)在奥氏体中的析出,但能够促进其在铁素体中析出;对于本试验钢,10℃/s的冷却速率即可抑制Nb(C, N)的析出;Nb(C, N)的析出粒子平均粒径随着冷却速率的增加而减小。     

低成本Q500E低合金高强度厚钢板的开发

为开发低成本Q500E低合金高强度厚钢板,系统研究了未再结晶区变形量和变形后冷却速率对一种低合金钢奥氏体连续冷却相变(CCT)行为和组织变化规律的影响。通过系列TMCP试验,探讨了精轧温度对试验钢板显微组织和力学性能的影响。结果表明,未再结晶区变形量、变形后冷却速率和精轧温度均能显著影响试验钢的显微组织和力学性能。生产低成本Q500E厚钢板的TMCP工艺为:在奥氏体再结晶区和未再结晶区进行两阶段轧制,精轧温度800～850℃,精轧压下率75%,轧后以高于10℃/s的冷却速率冷却至450～500℃。     

高性能海底管线钢的铁素体相变规律

采用Gleeble-1500D型热模拟试验机研究了高性能海底管线用钢的铁素体相变组织演变特征,观察不同变形温度、变形量和开冷温度对铁素体相变规律的影响。结果表明,增加变形量和降低变形温度均会促进形变诱导铁素体相变,加快铁素体析出,细化铁素体晶粒;降低开冷温度,铁素体转变量增加,但开冷温度过低时,铁素体晶粒会明显长大。为了获得细小弥散的铁素体组织,试验钢奥氏体未再结晶区变形温度应控制在780℃左右,变形量≥50%,开冷温度控制在700~660℃之间。     

低碳含铌细晶双相钢的组织控制

利用热模拟压缩变形实验研究了低碳含铌钢基于过冷奥氏体动态相变细晶双相钢的组织控制.相变前的奥氏体状态(再结晶奥氏体或形变奥氏体组织)及Nb的存在状态对动态相变有较大的影响.结果表明,由于铌在再结晶奥氏体中主要以固溶状态存在,其固溶拖曳作用延迟了铁素体动态相变,要求在动态相变中施以大的应变量才能获得细小马氏体岛弥散分布于细晶铁素体中的双相组织;形变奥氏体中,大部分铌在奥氏体未再结晶区形变中应变诱导析出,动态相变中固溶铌拖曳作用的降低以及未再结晶区形变对奥氏体有效晶界面积(Sv)的提高均有利于铁素体在动态相变中快速形核,在小应变量下即可获得铁素体晶粒为1～2μm,马氏体岛＜1μm的超细晶双相组织.     

控轧控冷工艺对J55石油套管用钢带状组织影响

为消除或减轻J55石油套管用钢带状组织,通过热轧试验研究变形温度、终轧温度、奥氏体未再结晶区压下率、轧后至卷取温度前冷速以及卷取温度等,对J55石油套管用钢带状组织影响规律。研究结果表明,随着变形温度的提高,金相组织中带状组织呈逐渐减弱趋势,而且终轧温度较高可以减少带状组织的产生。采用奥氏体未再结晶区大压下制度,不仅可以明显减少带状组织的产生,还可以细化晶粒。适当加大终轧后冷却速度,可消除或减轻铁素体+珠光体的带状组织。卷取温度对带状组织的消除或减轻无显著影响,建议适当降低卷取温度,以保证层流冷却的加速冷却。     

奥氏体-铁素体区循环形变对X60管线钢力学性能的影响

通过调整奥氏体-铁素体区循环形变参数,研究了铁素体区变形温度、奥氏体区变形温度、变形速率、冷却速度对X60管线钢力学性能的影响规律。实验结果表明:采用该循环变形工艺所得到的X60管线钢的铁素体晶粒大小为3.7μm,抗拉强度为639MPa,断面收缩率为79%,与CSP工艺下的组织相比,更加均匀细化,抗拉强度提高了16%。     

轧制与冷却工艺对高强度管线用宽厚钢板组织与性能的影响

利用工业试验和热模拟试验研究了未再结晶区轧制温度、弛豫时间、终冷温度对X80级管线用宽厚钢板微观组织和性能的影响。结果表明:在770～880℃的温度范围内,随着未再结晶区轧制温度的降低,钢中位错密度和形核位置增加,奥氏体向铁素体转变温度升高,铁素体体积分数增大,试验钢的屈服强度升高、韧性改善;终轧温度为790℃时,奥氏体晶界附近形成了细小连续的铁素体;弛豫过程通过对位错、溶质原子、析出相、微观组织等多方面的影响来引起性能的变化;终冷温度的降低会促进贝氏体铁素体(BF)的形成,并抑制Nb(CN)析出,使钢板获得良好的韧性和更小的屈强比。     

形变热处理工艺（TMTP）对T91钢显微组织的影响

在Gleeble1500热模拟实验机上采用热压缩实验方法，研究了形变热处理工艺即在奥氏体未再结晶区变形后直接淬火对T91铁素体耐热钢微观组织的影响。结果表明：形变热处理工艺明显优化了T91钢的组织结构，使T91钢的马氏体板条趋于细化，并且能生成更多纳米级碳氮化物颗粒来进一步进行组织强化，从而论述了采用形变热处理工艺来提高铁素体耐热钢耐热温度的可行性。     

奥氏体-铁素体区循环形变对X60管线钢力学性能的影响

通过调整奥氏体-铁素体区循环形变参数,研究了铁素体区变形温度、奥氏体区变形温度、变形速率、冷却速度对X60管线钢力学性能的影响规律.实验结果表明：采用该循环变形工艺所得到的X60管线钢的铁素体晶粒大小为3.7μm,抗拉强度为639MPa,断面收缩率为79%,与CSP工艺下的组织相比,更加均匀细化,抗拉强度提高了16%.     

热轧和加速冷却对C—Mn—Ti钢再结晶,相变和沉淀的影响

1.前言欲使钢材具有高的强度和良好的低温韧性,主要应使铁素体晶粒细化。而铁素体晶粒的细化主要取决于奥氏体再结晶温度下的奥氏体形变和奥氏体形变后在铁素体转变温度范围内的加速冷却。因此,研究在生产条件下未再结晶奥氏体区的温度范围十分重要。此外,应变诱导相变及沉淀的研究也将     

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 利用Gleeble 3800热模拟试验机，通过研究X70管线钢相变组织形成规律和再结晶规律，进行了两阶段多道次控轧控冷工艺模拟试验，了解优化精轧的开轧温度、终轧温度、穿水后冷却速率和弛豫时间等工艺参数对X70管线钢的微观组织结构的影响。结果表明，在优化后的控轧控冷工艺参数下，X70管线钢得到以针状铁素体为主的均匀细化的理想组织。     

A study of the microstructure of niobium-microalloyed pipe steel after different modes of controlled rolling with accelerated cooling

The phase composition and mechanical properties of rolled thick sheets from pipe steel 05G1MB produced by different modes of controlled rolling with accelerated cooling are studied. The effects of the temperature and deformation regime, of the final rolling temperature, and of the temperature of the start of accelerated cooling on the phase composition of the rolled sheets are considered. The temperature range in which intense reduction during rolling should be avoided in order to keep niobium in the solid solution of the γ-phase and to ensure subsequent segregation of fine niobium carbides in ferrite is determined.     

低Si-Mn含Nb、Ti热轧双相钢的工艺与性能研究

通过实验室热轧试验,研究了工艺参数(终轧温度、层冷开始温度、卷取温度)对低Si低Mn含Nb、Ti热轧双相钢的组织性能的影响。通过合理的工艺控制得到了含有80%～90%的多边形铁素体及10%～20%的岛状马氏体,强度级别为550～600MPa的双相钢。     

非调质钢F40MnV三辊楔横轧的实验研究

针对非调质钢F40MnV空心轴类件楔横轧成形问题,为获得最佳轧制与冷却工艺制度,在三辊楔横轧机上开展了轧制与冷却实验研究。利用正交法制定实验过程工艺参数,并将带有热电偶的试件进行轧制。轧后采用水冷,水冷加空冷,风冷,空冷4种方式进行冷却,得到相应的温度变化曲线。基于实验结果,采用金相分析和性能实验手段研究了温度、断面减缩率和冷却介质对F40MnV钢轧后冷态力学性能的影响。结果表明采用水冷加空冷、断面减缩率35%、轧制温度为950℃时的成形工艺可得到较为优良的力学性能。     

Effects of processing parameters on the bond strength of Cu/Cu roll-bonded strips

Roll bonding, widely used in manufacturing large layered composite sheets, is a solid phase method for bonding similar or dissimilar metals by rolling. In this study, the effects of process parameters such as rolling reduction, rolling temperature, rolling speed, initial thickness of strip, and surface roughness on the bond strength between two-layer strips of Cu/Cu were investigated. The strips were subjected to chemical and mechanical cleaning prior to rolling, and after rolling, bond strengths were measured using the peeling test. It was observed that increased reduction, rolling temperature, strip width, and surface roughness led to an increase in peeling strength while increased rolling speed and initial thickness of strips caused peeling strength to decrease. Results also showed that increasing the initial thickness of strips would increase threshold deformation.     

轧制工艺对双辊铸轧AZ61镁合金组织性能的影响

研究了利用双辊铸轧镁合金铸轧坯直接进行热轧的生产工艺,研究了不同热轧工艺过程对产品品质的影响.研究表明,在400℃热轧时,随着压下量增加,铸轧镁合金显微组织的再结晶程度提高,晶粒细化;随着轧制温度的提高,显微组织中孪晶减少,再结晶程度提高,晶粒变得均匀且细小;在400℃下连续热轧到1.5 mm,得到的板材力学性能最优.     

SiC颗粒增强Al-8.5Fe-1.3V-1.7Si的轧制工艺

研究了喷射沉积SiC颗粒增强Al-8．5Fe-1．3V-1．7Si板材的轧制工艺。探索了板材轧制过程中材料的密度变化规律及室温力学性能，通过金相、扫描电镜和透射电镜观察了其微观组织。研究表明，材料的致密化程度、轧制温度、轧制过程中道次压下量对材料的轧制性能有着重要影响。通过优化轧制工艺最终获得了良好的室温力学性能：490℃热轧材料的抗拉强度为535MPa，断后伸长率为7％。     

Optimization of Cold Rolling and Subsequent Annealing Treatment on Mechanical Properties of TWIP Steel

This research work studied the effect of cold rolling reduction and subsequent annealing temperature on the microstructural evolution and the mechanical properties of Fe-32Mn-4Si-2Al twinning-induced plasticity steel plates. For this, uniaxial tensile tests were carried out for three cold rolling reductions (50, 65 and 80%) and subsequent annealing treatment at 550-750 °C for 1.8 ks. The results were discussed in terms of the yield strength, ultimate tensile strength and total elongation and its dependence on the introduced microstructure. Regression analysis was used to develop the mathematical models of the mechanical properties. Moreover, analysis of variance was employed to verify the precision of the mathematical models. Finally, desirability function was used as an effective optimization approach for multi-objective optimization of the cold rolling reduction and annealing temperature. It is considerable that there is no research attempting to find optimum mechanical properties of the steels using this approach. The results indicated that applying large cold rolling reduction (upper than 75%) and subsequent annealing treatment in the recovery region and also the application of large cold rolling reduction and the subsequent annealing treatment in the lower limit of partial recrystallization region were effective methods to obtain an excellent combination of mechanical properties.     

变形参数对AZ31镁合金板材织构的影响

利用X射线衍射(XRD)方法测量了不同轧制状态,即不同变形温度和变形量条件下AZ31镁合金板材织构的变化特征。结果表明,经过轧制之后的AZ31镁合金板材形成强烈的基面织构;在250℃~400℃范围内,变形温度的升高、变形量的增大都会促进镁合金板材棱柱面、锥面等非基面滑移系的启动,从而影响各织构组分的锋锐程度和板材各向异性的强弱。随着变形温度的升高,镁合金板材的各向异性减弱;变形量的增大,镁合金板材的各向异性增强。     

Simultaneously Improving Mechanical Properties and Stress Corrosion Cracking Resistance of High-Strength Low-Alloy Steel via Finish Rolling within Non-recrystallization Temperature

The effect of hot rolling process on microstructure evolution,mechanical properties and stress corrosion cracking (SCC) resistance of high-strength low-alloy (HSLA) steels was investigated by varying the finish rolling temperature (FRT) and total rolling reduction.The results revealed granular bainite with large equiaxed grains was obtained by a total rolling reduction of 60％ with the FRT of 950 ℃ (within recrystallization temperature Tr).The larger grain size and much less grain boundaries should account for the relatively lower strength and SCC resistance.A larger rolling reduction of 80％ under the same FRT resulted in the formation of massive martensite-austenite (M/A) constituents and resultant low ductility and SCC resistance.In contrast,a good combination of strength,ductility and SCC resistance was obtained via 80％ rolling reduction with the FRT of 860 ℃ (within non-recrystallization temperature Tnr),probably because of the fine grain size and M/A constituents,as well as a high density of grain boundary network.