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101.
利用金相试验和差热分析方法,系统地研究了用镍基钎料钎焊1Cr18Ni9Ti时钎缝的重熔温度随钎焊工艺变化的规律。研究结果表明,熔化钎料与母材间的相互扩散是影响钎缝重熔温度的主要因素。当通过扩散使钎缝组织变成纯固溶体时,钎缝的重熔温度将大幅度提高。BNi1a、BNi2和BNi5钎缝的重熔温度可分别提高到1235℃,1230℃和1397℃。BNi7钎缝的重熔温度提高幅度较小,在试验条件下仅提高到945℃  相似文献   
102.
奥氏体不锈钢钻削变形系数的实验研究   总被引:1,自引:0,他引:1  
以奥氏体不锈钢1Cr18Ni9Ti为工件材料,应用最新研制的涂层钻头进行大量切削实验,研究钻削参数对变形系数的影响以及变形系数与轴向力、转矩和钻削温度之间的关系.结果表明,不锈钢钻削变形系数反应了轴向力的变化趋势.实验还揭示了奥氏体不锈钢钻削加工中切削速度和进给量的变化对变形系数的影响规律.研究结果为奥氏体不锈钢钻削刀具选择及其参数的优化提供了依据.  相似文献   
103.
大型水轮机叶片马氏体不锈钢的多相流损伤行为   总被引:2,自引:1,他引:1  
对水轮机用0Cr13Ni5Mo不锈钢及其精炼合金在蒸馏水和模拟长江水中进行了旋转圆盘仪空蚀和冲蚀以及二者组合的多相流损伤实验,并与普通13-4不锈钢进行对比分析·结果表明,精炼工艺改进后的0Cr13Ni5Mo不锈钢晶粒内部的铁素体组织得到了细化,抗冲蚀和多相流损伤能力明显高于原合金和13-4不锈钢·3种不锈钢的冲蚀、空蚀与冲蚀联合作用损伤累积失重-时间曲线均呈直线关系,空蚀和冲蚀联合作用对材料造成的损伤明显高于空蚀和冲蚀单独作用·  相似文献   
104.
UNS S32205 duplex stainless steel plates were welded to AISI 316L stainless steel using the pulsed gas tungsten arc welding process with three different filler metals: ER2594, ER312, and ER385. The microstructures of the welds were characterized using optical and scanning electron microscopy, and all of the specimens were evaluated by ferrite measurements. The mechanical properties were studied through hardness, tensile, and impact tests. In addition, the pitting resistance equivalent number was calculated and cyclic polarization tests were performed to evaluate the corrosion resistance of the weld metal. The results showed that chromium nitride was formed in the heat-affected zone of the duplex side, whereas no sigma phase was detected in any of the specimens. The ferrite number increased from the root pass to the final pass. The absorbed energies of the impact test decreased with increasing ferrite number, whereas the tensile strength was enhanced. The fully austenitic microstructure of the specimen welded with ER385 exhibited the highest resistance to pitting corrosion at 25°C, and the super-duplex weld metal presented superior corrosion resistance at 50°C.  相似文献   
105.
采用非真空热轧方法制备304不锈钢/Q235碳钢复合板材,利用OM、SEM、EDS等研究了不同压下率和轧后冷却方式下复合界面夹杂物、界面组织及力学行为的演变,并分析了C扩散对复合板界面组织形成及结合强度的影响。结果表明,随着轧制压下率的增加,界面夹杂物由块状向线型、连续点状乃至弥散点状分布变化。当压下率较低(28%)时,复合板剪切断裂位于结合界面处,随着压下率增加至47%及以上,复合板断裂位置为脱碳铁素体区。另外,热轧复合板经水冷工艺处理后,由于冷却速率较快,要抑制碳钢侧C元素的扩散,避免复合界面处脱碳区域的形成,从而提高了复合界面的结合强度。  相似文献   
106.
针对钠冷快中子增殖反应堆(简称快堆) 燃料元件包壳材料316 以及15-15Ti 奥氏体不锈钢, 讨论了通过晶界工程(grain boundary engineering, GBE) 技术进一步提高材料抗辐照肿胀以及抗蠕变性能的可行性. 通过GBE 技术能够大幅增加材料中与孪晶相关的低 重合位置点阵(coincidence site lattice, CSL) 晶界比例. 快堆燃料元件包壳在固溶退火处理后还要经过20% 左右的冷加工变形, 目的是在显微组织中引入大量位错, 吸收由辐照产生的点缺陷, 并增加吸收裂变产物的陷阱. 如果在这样的冷加工变形前大幅提高材料的低∑CSL 晶界比例, 使冷加工变形时的位错滑移在具有特殊取向关系的晶粒间的传播以及位错在特殊结构晶界处的堆积排列发生变化, 那么就有可能使冷加工后位错的分布状态有利于吸收更多的由辐照产生的点缺陷, 提高材料抗辐照肿胀的能力.  相似文献   
107.
The effect of thermal aging on the fatigue crack growth (FCG) behavior of Z3CN20-09M cast duplex stainless steel with low ferrite content was investigated in this study. The crack surfaces and crack growth paths were analyzed to clarify the FCG mechanisms. The microstructure and micromechanical properties before and after thermal aging were also studied. Spinodal decomposition in the aged ferrite phase led to an increase in the hardness and a decrease in the plastic deformation capacity, whereas the hardness and plastic deformation capacity of the austenite phase were almost unchanged after thermal aging. The aged material exhibited a better FCG resistance than the unaged material in the near-threshold regime because of the increased roughness-induced crack closure associated with the tortuous crack path and rougher fracture surface; however, the tendency was reversed in the Paris regime because of the cleavage fracture in the aged ferrite phases.  相似文献   
108.
This article reports the effects of Sn on the inclusions as well as the mechanical properties and hot workability of ferritic stainless steel. Precipitation phases and inclusions in Sn-bearing ferritic stainless steel were observed, and the relationship between the workability and the microstructure of the steel was established. Energy-dispersive X-ray spectroscopic analysis of the steel reveals that an almost pure Sn phase forms and MnS-Sn compound inclusions appear in the steel with a higher Sn content. Little Sn segregation was observed in grain boundaries and in the areas around sulfide inclusions; however, the presence of Sn does not adversely affect the workability of the steel containing 0.4wt% Sn. When the Sn content is 0.1wt%-0.4wt%, Sn improves the tensile strength and the plastic strain ratio and also improves the plasticity with increasing temperature. A mechanism of improving the workability of ferritic stainless steel induced by Sn addition was discussed:the presence of Sn lowers the defect concentration in the ultra-pure ferritic lattice and the good distribution of tin in the lattice overcomes the problem of hot brittleness that occurs in low-carbon steel as a result of Sn segregation.  相似文献   
109.
Microstructure observations and drop-weight tear test were performed to study the microstructures and mechanical properties of two kinds of industrial X70 and two kinds of industrial X80 grade pipeline steels. The effective grain size and the fraction of high angle grain boundaries in the pipeline steels were investigated by electron backscatter diffraction analysis. It is found that the low temperature toughness of the pipeline steels depends not only on the effective grain size, but also on other microstructural factors such as martensite-austenite (MA) constituents and precipitates. The morphology and size of MA constituents significantly affect the mechanical properties of the pipeline steels. Nubby MA constituents with large size have significant negative effects on the toughness, while smaller granular MA constituents have less harmful effects. Similarly, larger Ti-rich nitrides with sharp corners have a strongly negative effect on the toughness, while fine, spherical Nb-rich carbides have a less deleterious effect. The low temperature toughness of the steels is independent of the fraction of high angle grain boundaries.  相似文献   
110.
This study analyzes acoustic emission (AE) signals during the intergranular corrosion (IGC) process of 316L stainless steel welded joints under different welding currents in boiling nitric acid. IGC generates several AE signals with high AE activity. The AE technique could hardly distinguish IGC in stainless steel welded joints with different welding heat inputs. However, AE signals can effectively distinguish IGC characteristics in different corrosion stages. The IGC resistance of a heat-affected zone is lower than that of a weld zone. The initiation and rapid corrosion stages can be distinguished using AE results and microstructural analysis. Moreover, energy count rate and amplitude are considered to be ideal parameters for characterizing different IGC processes. Two types of signals are detected in the rapid corrosion stage. It can be concluded that grain boundary corrosion and grain separation are the AE sources of type 1 and type 2, respectively.  相似文献   
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