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双辊薄带连续铸轧熔池内金属流动及传热特性的研究 总被引:3,自引:0,他引:3
本文建立了双辊式薄带连续铸轧熔池内二维传热流动数学模型,使用有限元计算方法实现了控制方程及边界条件的数值求解,计算结果揭示了熔池内的流场、凝固温度场的特点和规律。 相似文献
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研究了铸轧AZ31镁合金的高温拉伸性能和变形机制.在300~450℃条件下,分别以恒定拉伸速率10-3 s-1和10-2 s-1进行拉伸至失效试验,在真实应变率为2×10-4~2×10-2 s-1的范围内进行变应变率拉伸试验.当拉伸速率为10-2s-1时,试样在400℃和450℃的延伸率均超过100%;当拉伸速率为10-3 s-1时,试样在400℃和450℃的延伸率均超过200%,该条件下的应力指数n≈3,蠕变激活能Q=148.77 kJ·mol-1,变形机制为溶质牵制位错蠕变和晶界滑移的协调机制.通过光学金相显微镜和扫描电子显微镜观察显示试样断口处存在由于发生动态再结晶和晶粒长大而形成的粗大晶粒,断裂形式为空洞长大并连接导致的韧性断裂. 相似文献
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化学成分和生产工艺对09CuPCrNi耐候钢性能的影响 总被引:1,自引:0,他引:1
介绍了09CuPCrNi耐候钢优良的综合性能。通过剖析Cr、P等合金元素在不同生产工艺条件下在钢中存在的形态,提示其对钢中耐候性影响规律和机理,提出降低铬的碳化物析出量是提高耐大气腐蚀性的有效措施,发现磷作为一种很强的上坡扩散元素有极明显的表面富集疚。富集可以通过热处理工艺增加,以便进一步提高耐大气腐蚀性能作用。 相似文献
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M2高速钢铸带组织特征及其后续处理 总被引:1,自引:1,他引:1
研究了M2高速钢在不同制备条件下的凝固组织特征以及工业铸带中碳化物在高温热处理、热变形作用下的变化,测量了在不同制备条件下高速钢的凝固速度和共晶碳化物网的厚度,采用透射电镜研究了后续高温热处理、热变形对工业铸带中碳化物相的影响,采用定量金相法分析了制备条件和后续处理工艺对铸带组织的影响.研究结果表明,双辊薄带连铸工艺可以细化高速钢凝固组织的枝晶和共晶碳化物网的厚度,改善碳化物的分布,后续高温热处理和热变形可以进一步优化工业铸带中的碳化物组织.建议在工业铸带的后续处理中同时采用高温热处理和热变形工艺以改善铸带组织. 相似文献
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The mechanical properties, corrosion resistance and microstructures of high performance steel (HPS) was investigated by tensile testing machine, Charpy V-Notch (CVN) testing machine, cyclic immersion corrosion tester, XRD, optical microscopy (OM), scanning electron microscopy (SEM), and electron probe micro-analyzer (EPMA). The results showed that significant differences existed in the tensile strength, yield strength and impact toughness between HPS and PCS. After 72 h cyclic immersion accelerated corrosion test, the inner rust layer on HPS was composed of α-FeOOH phase and denser than that on PCS that was a mixture of α-FeOOH and Fe3O4. The rust formed on HPS provides better protection and HPS has lower corrosion rates than PCS. Copper and chromium in HPS enrich in the rust layer and enhance the compactness of the rust layer. Based on the results of the accelerated corrosion tests and rust layer analysis, the roles of Cu and Cr against corrosion are discussed, providing HPS with chemical specification which has been industrially successful to produce weathering steel for bridge structure. 相似文献
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Effect of Heat Treatment on Structure and Wear Re- sistance of High Chromium Cast Steel ContainingBoron 总被引:1,自引:0,他引:1
The microstructure, mechanical properties and wear resistance of high chromium cast steel containing boron after different heat treatments were studied by means of the optical microscopy (OM), the scanning electron microscopy (SEM), X-ray diffraction (XRD), hardness, impact toughness, tensile and pin-on-disc abrasion tests. The results show that as cast microstructures of boron-free high chromium steel consist of martensite and a few (Cr, Fe)_7C_3 carbide, and the macro-hardness of boron-free high chromium steel is 55-57 HRC. After 0.5 mass% B was added into high chromium cast steel, as-cast structure transforms into eutectic (Fe, Cr)2B, (Cr, Fe)7 (C, B)a and martensite, and the macro-hardness reaches 58-60 HRC. High temperature quenching leads to the disconnection and isolated distribution of boride, and there are many (Cr,Fe)_23 (C,B)_6 precipitated phases in the quenching structure. Quenching from 1050 ℃, high chromium steel obtained the highest hardness, and the hardness of high chromium cast steel containing boron is higher than that of boron-free high chromium steel. The change of quenching temperature has no obvious effect on impact toughness of high chromium steel, and the increase of quenching temperature leads to tensile strength having an increasing tendency. At the same quenching temperature, the wear resistance of high chromium cast steel containing boron is more excellent than that of boron-free high chromium steel. High chromium cast steel guide containing boron has good performance while using in steel bar mill. 相似文献
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通过合适的成分设计和控轧控冷工艺开发出一种综合力学性能优异的Nb-V微合金化含Cu高强度耐候钢(/%:≤0.12C,≤0.40Si,≤1.40Mn,≤0.020P,≤0.010S,0.40~0.45Cr,0.25~0.35Cu, ≥0.020Al,0.02~0.03Nb,0.02~0.03V),并对其耐蚀性能进行了研究。该高强耐候钢组织由铁素体、珠光体和贝氏体组成,抗拉强度高达697 MPa,屈强比为0.73,断后伸长率为24.6%, -40℃纵向冲击功为70.6 J。盐雾及周期浸润试验结果表明,该钢耐蚀性能显著优于Q345B,其锈层主要由Fe3O4、α-FeO(OH)和γ-FeO(OH)构成,且随着时间增加,Fe3O4相对含量增加,α-FeO(OH)变化较小,γ-FeO(OH)减少。 相似文献
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Kelvin Y. Xie Sachin L. Shrestha Peter J. Felfer Julie M. Cairney Chris R. Killmore Kristin R. Carpenter Harold R. Kaul Simon P. Ringer 《Metallurgical and Materials Transactions A》2013,44(2):848-855
The current study investigates the strengthening of an Nb-microallyed CASTRIP® steel at 798 K (525 °C) by nitriding in a KNO3 salt bath. Nitriding up to 1 hour dramatically increased the yield strength of the steel by ~35 pct (from 475 to 645 MPa) with no sacrifice of ductility (~16 pct). Further nitriding led to brittle fracture. Hardness profiles of the nitrided steels through the thickness reveal hard surfaces and a relatively softer core. The hardening of the shell in the nitrided steels is thought to be the combined effect of solid solution strengthening from nitrogen and dispersion strengthening from clusters and precipitates. The retained ductility is attributed to the hard-shell–soft-core structure through nitriding. 相似文献