Effect of shot peening on hydrogen embrittlement of high strength steel

The effect of shot peening (SP) on hydrogen embrittlement of high strength steel was investigated by electrochemical hydrogen charging, slow strain rate tensile tests, and hydrogen permeation tests. Microstructure observation, microhardness, and X-ray diffraction residual stress studies were also conducted on the steel. The results show that the shot peening specimens exhibit a higher resistance to hydrogen embrittlement in comparison with the no shot peening (NSP) specimens under the same hydrogen-charging current density. In addition, SP treatment sharply decreases the apparent hydrogen diffusivity and increases the subsurface hydrogen concentration. These findings are attributed to the changes in microstructure and compressive residual stress in the surface layer by SP. Scanning electron microscope fractographs reveal that the fracture surface of the NSP specimen exhibits the intergranular and quasi-cleavage mixed fracture modes, whereas the SP specimen shows only the quasi-cleavage fractures under the same hydrogen charging conditions, implying that the SP treatment delays the onset of intergranular fracture.     

Effects of stress ratio on the temperature-dependent high-cycle fatigue properties of alloy steels

This paper addresses the effects of stress ratio on the temperature-dependent high-cycle fatigue (HCF) properties of alloy steels 2CrMo and 9CrCo, which suffer from substantial vibrational loading at small stress amplitude, high stress ratio, and high frequency in the high-temperature environments in which they function as blade and rotor spindle materials in advanced gas or steam turbine engines. Fatigue tests were performed on alloy steels 2CrMo and 9CrCo subjected to constant-amplitude loading at four stress ratios and at four and three temperatures, respectively, to determine their temperature-dependent HCF properties. The interaction mechanisms between high temperature and stress ratio were deduced and compared with each other on the basis of the results of fractographic analysis. A phenomenological model was developed to evaluate the effects of stress ratio on the temperature-dependent HCF properties of alloy steels 2CrMo and 9CrCo. Good correlation was achieved between the predictions and actual experiments, demonstrating the practical and effective use of the proposed method.     

外加纳米粒子强化钢铁材料研究的新进展

基于钢中二相粒子对钢的强化作用理论,向钢液中直接加入纳米氧化物粒子强化钢铁材料成为研究热点。目前国内的研究主要集中于粒子的添加方法、种类、影响等方面,但都回避了纳米粒子在钢中能否均匀分散的问题,也未见工业化应用的报道。国际上,研究主要集中于纳米粒子的制备及处理方法等方面,定性分析了粒子的分散性问题。为了使粒子能够均匀分散,粒子的制备和添加方法依然是难点,有关纳米粒子在钢液中的运动行为,热力学稳定性等问题还有待于进一步深入研究。     

跨中集中荷载作用的简支梁受拉翼缘受均布侧向约束的

摘要：本文运用编制的有限元程序对跨中集中荷载作用下等截面焊接工字形和轧制H型钢简支梁受拉翼缘受到连续侧向刚性约束的情况进行计算模拟分析,绘出稳定承载力提高系数ξ与扭转参数K的拟合公式曲线,进而得出了ξ—K曲线拟合公式,以此对该情况下梁的整体稳定系数 进行修正。     

钢衬钢筋混凝土蜗壳结构非线性分析

利用有限元法原理,考虑水工结构的特点,编制了钢针钢筋混凝土结构二维非线性有限元程序,并用已有的试验成果对非线性有限元分析进行了验证,最后利用该程序对某一高水头抽水蓄能电站蜗壳联合承载结构进行了计算分析。     

流程工业中模糊控制和故障诊断的建模及网络综合集成

研究流程工业中模糊控制和故障诊断的建模和网络综合集成．通过局域网集成系统实现各控制单元传感数据的共享以及流程生产过程的监控和报警,从而提高了制造系统的效率．提出了基于人工神经网和遗传算法的模糊控制建模方法,以及基于综合模型（人工神经网、案例、规则、对象模型）的故障诊断的建模和推理．     

成组技术应用模式的研究

在调查研究的基础上,系统地分析了我国近年来在成组技术（ＧＴ）应用中存在的若干误区。探讨了ＧＴ与ＣＡＤ／ＣＡＰＰ、ＧＴ与数控加工技术、ＧＴ与计算机集成制造（ＣＩＭ）等先进制造技术;ＧＴ与计算机技术、信息技术和网络技术,ＧＴ与ＭＲＰＩ等管理技术相结合应用的多种模式。为成组技术在企业产品设计、工艺设计、产品制造等的不同环节不同方面的应用或综合应用提供了相应的模式。     

碱性化学着色过程中不锈钢电势的测定

着重介绍了不同温度时碱性着色过程中不锈钢电势与着色时间的关系,并讨论了温度和添加剂亚硫酸钠对碱性着色过程的影响．     

Nb-Ti微合金钢高温变形软化行为力学分析及析出物电镜分析

研究了Nb-Ti微合金钢高温变形时的软化行为和微合金钢动态和静态析出物的电镜分析.通过双道次恒应变速率压缩实验,从流变应力曲线用卸载法求出了不同热变形条件下的软化分数,并建立了静态再结晶、亚动态再结晶动力学模型,计算出静态再结晶、亚动态再结晶的表观激活能.同时,还对静态和动态析出行为进行了探讨,讨论了析出对软化行为的影响,并通过透射电子显微镜对析出物的形貌、大小、分布进行了观察,用衍射图谱进一步确定了析出物的成份.     

猕猴桃果汁饮料生产相关工艺研究

介绍了猕猴桃果汁饮料的生产工艺 ,比较了不同榨汁方法的出汁率与提汁速度 ,探讨了提高猕猴桃果汁饮料稳定性 ,保护Vc和色泽和工艺和方法