热处理工艺对12Cr1MoV钢显微组织和力学性能的影响

通过热模拟试验对12Cr1MoV钢进行了不同工艺的正火+回火热处理,研究了热处理工艺对该钢显微组织及力学性能的影响。结果表明:12Cr1MoV钢正火+回火后的正常显微组织为回火贝氏体+铁素体或回火贝氏体+铁素体+珠光体或铁素体+珠光体;如果回火温度过高或正火冷却速率不足,则分别会导致钢中出现两相区组织黄块马氏体和钒的碳化物沿晶界及晶内聚集长大的情况,显著降低钢的力学性能。     

回火温度对600 MPa级薄钢板显微组织和强韧性的影响

为了分析回火温度对薄钢板显微组织和力学性能的影响,对6mm厚的钢板进行了淬火和回火的热处理。实验结果表明,淬火后薄钢板抗拉强度达到600 MPa以上,显微组织为马氏体和贝氏体,中部与边部无明显差异。回火温度对钢板表面硬度影响甚微,延长回火后保温时间有利于提升钢板韧性。淬火加低温回火后的拉伸断口呈现韧性断裂特征。采用实验所用的淬火及热处理工艺,可以提升钢板的力学性能和表面硬度,以及改善钢板组织和性能的均匀性。     

热处理工艺对Q245R钢板组织和性能的影响

通过进行显微组织观察和拉伸、冲击、硬度等力学性能试验,研究了不同加热温度、保温时间、冷却方式的热处理工艺对Q245R钢板组织和性能的影响。结果表明:加热温度与冷却方式对Q245R钢板性能影响较大,加热到Ac1以上保温后空冷可适当降低钢板硬度和强度、提高钢板韧性,并且随着保温时间的延长,可使钢板强度和硬度下降;加热到Ac1以上保温后水冷,加热温度越高,水冷后获得钢板的强度、硬度也越高,韧性则越低。     

590MPa高强度船用钢板调质工艺的优化

为提高590 MPa船用钢板的综合力学性能,对40 mm厚船用HQ60T钢板进行了调质工艺的研究.采用不同的正火工艺获得了不同的组织结构,进行了不同淬火和回火温度的热处理试验,对不同试样进行了金相分析和力学性能的试验,详细观察了各种热处理状态下试验钢的微观组织,讨论了组织演变规律及其对性能的影响.试验表明:相同调质处理条件下,随着正火温度的提高,钢板强度下降,韧性提高;在580℃回火的条件下,韧性指标随淬火温度的升高,先升高后降低,在920℃时出现峰值;回火温度高于580℃,钢板韧性下降,强度下降加快.研究表明,在920℃时水淬,然后580℃回火时钢板综合力学性能最好.     

低焊接裂纹敏感性钢回火组织及力学性能研究

为优高强度低焊接裂纹敏感性钢的力学性能,对其热轧态钢板进行了不同温度的回火实验.通过光学显微镜、扫描电镜和透射电镜观察了回火显微组织的演变特征,并结合相应的力学性能检测手段分析了不同回火温度下显微组织与力学性能的关系.结果表明,550℃回火后屈服强度和抗拉强度较热轧态强度分别提高了115和30 MPa,平均冲击功提高了...     

热处理保温时间对25Mn2钢力学性能和显微组织的影响

对25Mn2钢进行了不同工艺的热处理,研究了淬火保温时间和回火保温时间对其力学性能和显微组织的影响,以探讨优化其热处理工艺的可能性。结果表明：回火保温时问对力学性能的影响是显著的,而淬火保温时间对力学性能的影响并不显著;在淬火温度为900℃,回火温度为615℃的条件下,回火保温20min是必要且足够的;经优化后工艺热处理25Mn2钢的力学性能能较好地满足API5CT标准要求。     

CSP流程生产低碳高强度汽车板组织性能的研究

研究了珠钢电炉CSP工艺生产低碳高强度钢板的热轧工艺与组织性能之间的关系,通过光学显微镜和力学性能试验等检测分析技术分析了控制轧制和冷却各阶段工艺参数对成品板显微组织和力学性能的影响.研究表明:降低终轧温度和卷取温度可有效细化晶粒,提高钢板的强度;采用适当的控轧控冷工艺制度,可以获得不同强度级别强韧性能良好的热轧低碳高强度汽车用钢板.     

低碳微合金石油储罐钢回火工艺研究

以含0.012Ti大型石油储罐用钢为研究对象,分析了不同回火温度对淬火后的石油储罐用钢性能和组织的影响.结果表明回火时间相同,随回火温度的升高,钢板力学性能变化趋势并非单调性,硬度和强度先升高后降低,韧性和塑性先降低后升高.在605～635℃窄区间回火温度对金相组织演变的差异较小,没有出现本质上的不同.原轧态淬火钢经回火后的显微组织由板条贝氏体+马氏体组织逐渐转变为粒状贝氏体、板条贝氏体及回火马氏体混合组织,板条边界依然清晰可见,说明回火过程只发生回复并没有再结晶.     

桥梁用钢板14MnNbq的试制开发

介绍了桥梁用钢板14MnNbq的试制开发情况,进行了控轧及热处理试验,并分析了钢的化学成分、轧制及冷却工艺对钢板性能的影响作用,最终得出14MnNbq钢板的生产工艺.     

热处理温度对IF钢板第二相粒子和力学性能的影响

对退火态IF钢板进行了不同温度的热处理,研究了热处理温度对IF钢板显微组织和力学性能的影响。结果表明:IF钢板中弥散分布着含碳第二相粒子;随着热处理温度的升高,显微组织中的含碳第二相粒子减少,IF钢板屈服强度和抗拉强度逐渐增加,塑性应变比r值和拉伸应变硬化指数n值则逐渐减小,即钢板深冲压性能降低。     

Effect of interfacial compounds on mechanical properties of titanium–steel vacuum roll-cladding plates

The titanium–steel clad plates were prepared by vacuum roll cladding. Ti–Fe compounds and TiC were observed at different cooling rates after rolling. Optical microscopy, electron microprobe analyser, X-ray diffraction and shear test studies were carried out to study the effect of Ti–Fe compounds and TiC on the ultimate microstructure and mechanical properties of titanium–steel clad plates. At a cooling rate of 6.2°C/min, TiC and Ti–Fe compounds seriously impacted the mechanical properties of the clad plate. At a cooling rate of 1.8°C/min, the thickness of the TiC layer was optimal much that the maximum shear strength of 296?MPa was obtained. At a cooling rate of 0.6°C/min, the thickness of the TiC layer was relatively thick, which affected the mechanical properties of clad plates.     

Studies on influence of reheating temperature and cooling rate on structure–property behaviour of lean chemistry HSLA-100 steel

Abstract

Simulation studies on the influence of reheating temperature on austenite grain coarsening in lean chemistry high strength low alloy (HSLA)-100 steel were carried out to establish optimum soaking temperature before hot rolling. Experiments carried out in ‘Gleeble-3500’ dynamic thermomechanical simulator revealed that prior austenite grain sizes varied between 26 and 98 and 34 and 126 μm after soaking at 1150, 1200 and 1250°C for 1 and 5 min respectively; a soaking temperature of 1200°C was found to be optimum. Simulation experiments on the influence of cooling rate on microstructural changes and dilatometric studies indicated lowering of transformation temperature with faster cooling. Microstructural examination of dilatometric samples confirmed martensitic transformation at faster cooling rate. The martensite structure is desirable to achieve better strength and toughness. The findings of simulation studies were subsequently used for standardising thermomechanical treatments of Nb–Cu bearing lean chemistry HSLA-100 steels. One laboratory heat of Cu bearing HSLA steel containing 0·028%Nb was made. This heat was hot rolled into 12·5 mm thick plate by varying finish rolling temperature in the range of 800–1000°C. The soaking temperature was maintained at 1200°C. The rolled plates were heat treated by both conventional reheat quenching and tempering (RQT) as well as direct quenching and tempering (DQT) techniques. Evaluation of mechanical properties revealed that plates processed through DQT route were superior to those processed through RQT route. Transmission electron microscopy revealed that martensite structure and finer interlath spacing in DQT plates resulted in superior strength and impact toughness properties as compared to RQT steels.     

Prevention of surface hot shortness,development of banded structure,and mechanical properties of hot rolled Cu-bearing steel

The development of microstructural banding and surface hot shortness during hot rolling in a 1.4 wt% Cu-bearing steel was studied. Different hot rolled states were produced by cross rolling, air cooling, and furnace cooling to investigate the effect of initial microstructure on the mechanical properties. It was revealed that to insure the hot workability of Cu-bearing steel against liquid metal embrittlement and prevention of the failure, a good practice is conducting hot working operations at temperatures below the melting point of copper to suppress the formation of liquid Cu-enriched phase that penetrates into grain boundaries. Cross rolling was found to be a promising approach to decrease the anisotropy of the rolled sheets resulted from the presence of the banded structure. Moreover, air-cooling yielded maximum strength due to its resultant fine and complex microstructure. These results can find application in processing and optimization of mechanical properties of steel sheets.     

样品取向对轧制钢板拉伸性能的影响

分别对不同厚度、不同取向(α=0°,45°,90°)的SPCC冷轧钢板、SPHC热轧钢板、SUS304冷轧不锈钢板和SUS304热轧不锈钢板进行了拉伸试验,研究了取向因素对轧制钢板拉伸性能的影响,并分别探讨了钢板厚度、轧制状态和钢板材料等因素引起的拉伸性能各向异性程度的差异。结果表明:样品取向对轧制钢板的拉伸性能有明显影响,轧制方向的抗拉强度和断后伸长率较高,而屈服强度的变化规律则较为复杂;钢板厚度、轧制状态、钢板材料等因素对轧制钢板拉伸性能的各向异性都有不同程度的影响。     

Influence of the annealing cooling rate on the microstructure evolution and deformation behaviours in the cold ring rolling of medium steel

Pre-heat treatment is a necessary step of cold ring rolling that leads to different microstructure evolution processes and different macroscopic deformation behaviours of rings in the cold ring rolling process. In this paper, the cold ring rolling process of 1045 steel with different annealing cooling rates is studied because the annealing cooling rate is the factor with the greatest influence on the result of the pre-heat treatment. By subjecting 1045 steel to different annealing cooling rates, it is found that, within the experimental range, the grain size of the rings becomes smaller and the lamellar spacing of pearlite decreases as the annealing cooling rate increases, resulting in a stronger and tougher material. The ABAQUS finite element (FE) software was employed to simulate the cold ring rolling process. The simulations indicated that increasing the annealing cooling rate causes the stress in the rolled rings to increase, the strain to decrease and the cementite lamellae to become more fractured.     

热加工对管线用低碳钢性能的影响

通过热模拟实验,研究了一种管线钢相变组织的形成规律,在此基础上,进行两阶段多道次控轧和在适度冷却速度下控冷的控制热加工实验,分析了工艺参数对钢的组织结构和力学性能的影响。结果表明,开轧温度、终轧温度、终冷温度和冷却速度对管线钢的力学性能有强烈的影响。通过优化工艺,获得了以针状铁素体为主的混合组织,针状铁素体的含量越多,材料的力学性能越好。     

工艺参数对20MnSi热轧棒材力学性能的影响

通过研究规格为φ14mm的20MnSi热轧棒材工艺参数,指出在终轧温度为850℃左右时,以0．5～2．0℃／s的速度冷却至650℃,得到的20MnSi热轧成品棒材组织晶粒更细小,力学性能更高。与常规轧制相比,对20MnSi热轧棒材参数进行控制,抗拉强度提高60MPa,晶粒直径平均缩小2．2μm。     

Evolution of texture at the initial stages of continuous annealing of cold rolled dual-phase steel: Effect of heating rate

The performance of cold rolled dual-phase (DP) steels depends on their microstructure, which results from the thermomechanical processing conditions, involving hot rolling, cold rolling and continuous annealing. In the present work, the effects of intercritical annealing parameters i.e. heating rate, soaking temperature and time and the cooling rate on the texture and microstructure of a cold rolled DP steel (0.08%C–1.91%Mn) were investigated after simulating through Gleeble thermomechanical simulator. The soaking temperature was chosen in a way that all the ferrite has recrystallized before the temperature was reached. The three different heating rates allowed the samples to get recrystallized in three different ways: below Ac₁, just around Ac₁ and above Ac₁. {3 3 2} fiber texture along with {1 1 2} 1 1 1 texture component were observed after heating to the soaking temperature as well as after slow cooling. The overall intensity of the texture as well as textural component was observed to be nearly independent of the heating rate as well as cooling rate. The textural evolution was correlated with the volume fractions and morphology of carbides, which depend on the annealing processing parameters.     

Metallurgical investigation into the causes of premature failure of high-carbon steel wire rods during hot rolling

Wire rods of high-carbon steel, in sizes ranging between 5.5 and 14 mm, are normally produced from continuously cast billets by hot rolling in a wire rod mill. These wire rods are usually supplied to wire drawing plants in either the hot rolled or the controlled-cooled condition. The microstructure of the hot rolled wire rods is a coarse lamellar pearlite and is unsuitable for large reductions by cold drawing. In contrast, the microstructure of controlled-cooled wire rods is a relatively fine pearlite, developed as a consequence of in-line water and forced-air cooling, and is suitable for large reductions by cold drawing. Although wire rod breakages in modern-day mills are comparatively rare, they nonetheless may take place due to a variety of factors. The failure of wire rods, hot rolled or controlled cooled, may occur as a result of improper rolling schedule, cobbles, sudden mill stoppages and/or accelerations, and processing inadequacies that lead to the formation of inappropriate microstructures. A comprehensive metallurgical investigation may therefore be necessary to discover the genesis of wire rod breakages during rolling and/or finish cooling operations. This paper focuses on the microstructural causes of breakage of controlled-cooled high-carbon steel wire rods during hot rolling and attributes most failures to the formation of hard martensite layers that facilitated crack generation.