X70钢在酸性土壤模拟溶液中的应力腐蚀行为

在不同的阴极保护电位下,采用慢应变速率拉伸实验、动电位极化方法以及SEM研究了X70钢在酸性土壤模拟溶液中的应力腐蚀行为.结果表明: X70钢发生穿晶应力腐蚀裂纹;应力腐蚀开裂(SCC)萌生与外加保护电位有关,完全受阳极过程控制时X70钢的SCC敏感性较低,但会发生点蚀和严重的均匀腐蚀;受混合电极过程控制和全受阴极过程控制时均能发生SCC;受混合电极过程控制时,SCC二次裂纹与点蚀伴生,裂纹形核密度大;而完全受阴极过程控制时,SCC裂纹附近未见点蚀坑,裂纹形核密度低;混合电极过程控制时比完全阴极电极过程控制下更容易发生SCC裂纹.     

T615KJ落地镗床的电气改造

T615KJ落地镗床机械结构主要是仿前苏联2A系列的落地镗床.进给部分主要包括主镗杆、立柱、主轴箱和径向刀架共四个部分.经过近三十年的使用,其电气部分已经严重老化,本文是对电气部分实施改造的小结.     

大直径厚壁X70级钢管与绝缘接头基材P460NH管段的焊接

分析了X70级管线钢和P460NH正火钢的焊接性及其相互焊接应注意的问题。提出了大直径厚壁X70钢级钢管与绝缘接头基材P460NH管段在水平固定位置对接焊时,为获得背面成形好、致密性高、含氢量低、综合力学性能较好、接头熔合区无脆硬组织的焊接接头可采用的焊接工艺及相应技术措施。     

Hundredhands

Directed by Sunitha Kondur and Bijoy Ramachandran, Hundredhands is a multidisciplinary design studio whose work draws on a keen sense of the urban. In their projects, often represented in patiently executed analytical drawings, the architects have redirected their focus on the urban context by returning to questions of scale, character, spatial and visual impact, and remaking the public domain, all of which is so vital to the tempestuous urbanism of Indian cities. Copyright © 2007 John Wiley & Sons, Ltd.     

空冷弛豫对X70级抗大变形管线钢组织性能的影响

用显微组织分析,力学性能检测以及SUPPA55场发射扫描电镜,研究轧后空冷弛豫对X70级抗大变形管线钢综合性能的影响。结果表明,在相同的轧制工艺下,试验钢随着空冷弛豫时间延长,入水温度降低,先共析铁素体的量和析出物的量都逐渐增多,前者的软化效果与后者的析出强化共同作用,使强度和塑性变化复杂化。试验钢存在最佳的一个入水温度区间,获得先共析铁素体+贝氏体的双相组织,两者呈层状交叠分布,在软化和强化效果的综合作用下得到了抗大变形管线钢X70级所要求的强度塑性最佳匹配。     

HTP X70级热轧卷板的研究开发与应用

介绍了化学成分、轧制工艺对HTP X70级热轧卷板的性能影响,以及HTP X70级钢的应用情况。研究表明:低C－Mn－高Nb的HTP钢,随着Nb含量的增加,屈服强度、抗拉强度增加;在低C－Mn－高Nb的HTP钢成分的基础上,加入Mo或以Cr代Mo、以Cr部分替代Mo均可以提高钢的强度,但韧性下降;单独添加Mo,钢的韧性下降最少,其次为以Cr部分代替Mo的钢。随着终轧温度的降低,HTP X70级钢的强度、断裂韧性升高,与低Nb X70级钢相比,HTP X70级钢具有更高的冲击功。随着卷取温度的升高,强度升高,在600 ℃达到最高值;但是随着卷取温度的升高,断裂韧性下降。武钢已批量生产189 832 t HTP X70级钢,批量生产稳定。HTP X70级钢包辛格效应、冷变形导致管体屈服强度下降35 MPa,屈强比下降0.033,韧性下降近18 J,塑性下降3.5%;HTP X70级钢管管体性能、焊缝、热影响区的低温韧性优良。     

ACI集束氧枪和BSE炉门碳-氧枪复合吹炼技术在70 t电弧炉上的 应用和改进

在70t DE EAF加铁水25%～45%的情况下,通过合理的供氧模式,根据钢中留碳量和磷含量的要求确定炉渣碱度等工艺措施,采用复合吹炼技术有效地实现脱磷和留碳操作,杜绝了大沸腾事故,铁耗、氧耗、煤气消耗和冶炼周期分别从工艺改进前的1075 kg/t、37 m³/t、8.1 m³/t和54 min降低至1072 kg/t、33 m³/t、7.7 m³/t和52 min。仅电耗从338 kWh/t增至344 kWh/t。     

Risk assessment of Hydrogen fueling stations for 70 MPa FCVs

People are placing their hopes on the future of fuel-cell vehicles (FCVs) to replace today's gasoline-fueled vehicles. To encourage the widespread use of FCVs, however, these vehicles must be able to drive a distance of at least 500 km, mileage comparable to today's gasoline-fueled vehicles. To achieve this distance, automobile manufacturers are focusing their efforts on developing new hydrogen fuel tanks that will raise pressure to 70 MPa from the current 35 MPa. At the same time, hydrogen stations will also have to be able to provide 70 MPa compressed hydrogen gas to service these improved FCVs. Regulations for hydrogen fueling stations where pressure is no higher than 40 MPa were established in 2005 in Japan but it goes without saying that these regulations are inadequate for hydrogen fueling stations of 70 MPa.     

6RA70直流调速系统的优化

主要介绍了6RA70直流调速系统的优化方法和相关注意事项,以实例的方式展示了一些关键参数的设置以及操作流程.     

Covalent incorporation of [70]fullerene into poly(p-methylstyrene) by anionic copolymerization

A soluble non-crosslinked C₇₀-p-methylstyrene (C₇₀-PMS) copolymer was prepared in sodium naphthalene-initiated anionic polymerization reaction. This copolymer exhibits the lower intrinsic viscosity and higher absolute molecular weight compared with linear polystyrene at equal retention time, suggesting that the copolymer possess star-shaped structure. The covalent graftings of multiple poly(p-methylstyrene) (PPMS) chains onto the C₇₀ core result in the marked enhancement of the absorption degree at longer wavelengths, and in the increase of glass transition temperature. Like pure PPMS, C₇₀-PMS copolymer also exhibits the higher solvency in common solvents.