A study on tensile and fatigue properties of aged NAS 254N stainless steel at elevated temperatures

The effects of aging on tensile properties and fatigue crack growth behaviors of NAS 254N stainless steel was studied. Yield strength and ultimate tensile strength of the aged specimens were almost the same as the as-received (as-rec.). The fracture strain, however, was decreased significantly by the aging, and the fracture surface of the aged at room temperature (RT) test was intergranular. As test temperature increased, yield strength, ultimate tensile strength and elongation decreased. And a type of serration was observed at 550-650°C As strain rate decreased, yield strength and ultimate tensile strength decreased, but elongation increased. It was observed that tensile strength and strain had a sudden change at one point. And this critical temperatureT _cr was 550°C. The effect of aging time on the tensile strength and strain was also investigated. Tensile strength and strain decreased significantly beyond 100hrs. Fatigue crack growth rate at RT was enhanced by the aging at high stress intensity factor range. This is due to the occurrence of the intergranular fracture in the aged specimen. At 650°C, the fatigue crack growth behavior was almost the same without intergranular fracture.     

羧甲基纤维素接枝AM/DMDAAC共聚物作为泥浆处理剂的性能

考察了羧甲纤维素枝丙烯酰胺／二甲基二烯丙基氯化铵共聚物作为聚合物钻井液处理剂抑制粘土水化膨胀性能,配浆性能以及可生物降解性能,着得研究了ＣＡＤ分子结构对其性能的影响,同时探索了ＣＡＤ控制粘土水化与提高低固相泥浆粘度的作用机理。     

疏水缔合水溶性聚合物的溶液性质

疏水缔合水溶性聚合物是一种在亲水性大分子链上含有少量疏水基团的水溶性聚合物,具有独特的溶液性质,本文就该种聚合物的结构和组成,分子量,温度,剪切速率,溶液离子强度,表面活性剂和离子基团对聚合物在水溶液中流体力学行为的影响进行了综述。     

AM/MEDMDA阳离子型疏水缔合水溶性聚合物的合成与表征

采用自由基水溶液共聚法制备了水溶性的丙烯酰胺／（２－甲基丙烯酰基）氧乙基二甲基十二烷基溴化铵（ＡＭ／ＭＥＤＭＤＡ）共聚物。用元素分析、ＩＲ等方法对其结构进行了表征。疏水单体具有表面活性特征,所以在制备共聚物时不需要再加入表面活性剂。     

两种微交联羧甲基纤维素的结构和性能研究

在制备羧甲基纤维素（ＣＭＣ）过程中加入适量四硼酸钠或Ｎ－羟甲基丙烯酰胺（ＨＭＡＭ）使ＣＭＣ分子间发生微交联。阐述了有关的交联机理,研究了交联剂量对ＣＭＣ溶液性质的影响。结果表明,微交联工艺使ＣＭＣ溶液粘度、抗盐性和取代基分布均一性明显提高。与未交联ＣＭＣ比较,四硼酸钠用量３％—９％时,２％水溶液粘度提高２０％—６０％,盐粘比提高２３％—４９％,造浆率和滤失性也得到改进。用ＸＲＤ和ＩＲ对微交联ＣＭＣ结构进行了表征。     

A comparative study of catalytic behaviors of Mn,Fe, Co,Ni, Cu and Zn–Based catalysts in steam reforming of methanol,acetic acid and acetone

This study investigated the distinct catalytic behaviors of mono Mn, Fe, Co, Ni, Cu and Zn catalysts in the reforming of the small organics including methanol, acetic acid and acetone. The results showed that Mn, Fe or Zn-based catalysts showed almost no activity for steam reforming of either methanol, acetic acid or acetone, due to their low capacity to break the chemical bonds of the organics or to activate steam. Co and Cu-based catalysts were generally active for steam reforming of methanol. Nevertheless, Co-based catalysts promoted methanol decomposition to form a substantial amount of CO. Alumina as a support remarkably influenced catalytic stability of the catalyst. The unsupported Cu catalyst showed a much lower stability than Cu/Al₂O₃. Nevertheless, the unsupported Ni was more stable than Ni/Al₂O₃ catalyst, due to its high resistivity towards coking. The unsupported Co, however, was prone to coking. The C/H ratios in the coke formed over the unsupported and alumina-supported Ni or Co catalysts were distinct, indicating the involvement of alumina in the coking process. In addition, Ni and Co catalysts behaved differently. Ni/Al₂O₃ showed a superior stability than Co/Al₂O₃ in steam reforming of acetone. The coke formed on Ni/Al₂O₃ was more aromatic than that over Co/Al₂O₃ catalysts while morphologies of coke (nanotubes over Ni/Al₂O₃ versus fibrous coke over Co/Al₂O₃) were also different.     

HAT循环中关键部件_饱和器实验台的研制

本文指出了研究ＨＡＴ循环中的饱和器性能的必要性。并初步建立了饱和器性能实验台,为掌握饱和器性能深入研究ＨＡＴ循环作好了实验准备。     

国产X65卷板及钢管在库鄯管道的应用

通过对宝钢产Ｘ６５高强度,高韧性卷板的化学成分和力学性能的检验,证明其产品化学成分及机械性能稳定,波动范围不,具有良好的低温冲击性和低温抗动态撕裂能力,且各项理化检验指标均满足“库鄯输管道工程补充订货热轧卷板技术的要求”,制管后在线使用情况良好。     

钛对铝铜合金铸件力学性能的影响

通过试验研究钛的含量对ＡｌＣｕＭ ｎ 合金力学性能的影响,并从理论上进行了探讨,指出适量的钛对抗拉强度影响较大,对伸长率与硬度几乎没有影响。     

原始组织对等淬球铁组织与性能的影响

研究了原始基体组织分别为铁素体和珠光体的球铁等淬后显微组织与性能的差别,结果表明：原始组织为珠光体基体的球铁,等淬后其显微组织中的白亮区较多,硬度值较高,而冲击韧度略低。