Effects of increased solar ultraviolet radiation on materials

Synthetic polymers such as plastics, as well as naturally occurring polymer materials such as wood, are extensively used in building construction and other outdoor applications where they are routinely exposed to sunlight. The UV-B content in sunlight is well known to affect adversely the mechanical properties of these materials, limiting their useful life. Presently their outdoor lifetimes depend on the use of photostabilizers in the case of plastics and on protective surface coatings in the case of wood. Any increase in the solar UV-B content due to a partial ozone depletion would therefore tend to decrease the outdoor service life of these materials. It is the synergistic effect of increased UV radiation with other factors such as the temperature that would determine the extent of such reduction in service life. The increased cost associated with such a change would be felt unevenly across the globe. Those developing countries that depend on plastics as a prime material of construction and experience high ambient temperatures are likely to be particularly affected in spite of the relatively small fractional decrease in ozone at those locations. Assessment of the damage to materials, associated with ozone depletion, requires a knowledge of the wavelength dependence as well as the dose-response characteristics of the polymer degradation processes of interest. While the recent literature includes some reliable spectral sensitivity data, little dose-response information has been reported, so it is difficult to make such assessments reliably at the present time. This is particularly true for the naturally occurring materials popularly used in construction applications. To maintain polymers at the same useful lifetime in spite of increased solar UV-B content, the amount of photostabilizers used in the formulations might be increased. This strategy assumes that conventional stabilizers will continue to be effective with the spectrally altered UV-B-enhanced solar radiation. While the present understanding of the degradation chemistry suggests the strategy to have merit, its effectiveness, in an altered solar radiation environment, has not been demonstrated for common polymers. The availability of these data is crucial for reliably estimating the cost of mitigating the increased damage to materials as a result of a possible partial depletion of the ozone layer using this approach.     

180 t转炉经济炉龄控制模式实践

通过对鞍钢180 t转炉经济炉龄的分析,得出转炉最佳经济炉龄约为4 500炉,同时得出相应的炉衬维护方案,依据分析结果进行了工业实践。结果表明,在保证耐材成本最低化的同时,实际炉龄达到了4 401炉,耐材成本指数降低14.5%,全炉役复吹比率从27.3%提高到97.4%,平均碳氧积从0.003 0降低到0.002 4。     

Fatigue and Compression Characteristics of Al 6061–B 4 c Composite Materials

Aluminum matrix composites reinforced with boron carbide are a kind of materials that are widely used because of high strength, low density, and improved tribological properties. In this study, mechanical properties of Al 6061–B4C composites reinforced with B4C of three different particle sizes were investigated. In the Al 6061–B4C composite materials, produced by the powder metallurgy methods (extrusion of billets obtained by sintering at temperature of 550°C under pressure of 450 MPa), the change of mechanical properties such as hardness, compressive strength, and fatigue life, related to B4C particle size and the applied heat treatment mode (aging at 180°C for 5 h), were investigated. The hardness of the materials is increased with B4C grain size and the heat treatment. After the heat treatment, the fatigue life of Al 6061–B4C (3 μm) material increases slightly, while that of the composite materials decreases with larger size of B4C reinforcement. The fatigue life of the composite materials reinforced with a larger grain size B4C is reduced by heat treatment. While the compression test data of untreated composite materials were similar to each other, the heat treatment increased these values in all samples. The highest increase in the compression strength was observed in the composite reinforced with 17 μm sized B4C. The addition of graphite reduces the deformation ability of the composites.     

提高竖炉使用寿命的生产实践

针对竖炉在生产过程中造成的耐火材料损耗,通过对竖炉炉体砌筑方式及顶部防撞铜块的改造,在不改变竖炉砌筑成本的前提下,增加了炉体的耐冲击性,延长了竖炉的使用寿命,同时具备了废铜模、溜槽铜等大块物料的处理能力,大量节约了耐火材料及大块物料的处理费用。     

250 t转炉烟罩加料溜槽寿命研究及其焊接工艺

针对转炉烟罩加料溜槽寿命过短的问题进行失效分析，发现堆焊层厚度不足，焊后热处理效果不佳，裂纹扩展，宽窄不均，呈现热疲劳特征，并可见碳化物和共晶组织脱落。根据加料溜槽底面及侧面工作状态的不同，底面改用堆焊层硬度稍高的焊条堆焊，使堆焊层耐磨性增加，侧面改用韧性较好、焊态硬度稍低的不锈钢堆焊焊条堆焊，既改进了溜槽性能，又降低了生产成本。     

电炉使用铁水冶炼不锈钢母液提高炉龄的工艺实践

分析了影响冶炼不锈钢的电炉炉龄的主要因素。通过选用高质量耐火材料,提高炉衬抗氧化和耐侵蚀性;采用约45%的铁水热装比优化配料模式,以及优化供电曲线以降低电能消耗;采用渣泡沫化技术改进造渣工艺等提高电炉炉龄综合控制技术,电炉炉龄明显提高。2008年平均炉龄为507炉,最高炉龄达到了790炉。电炉炉龄作为一项体现冶炼综合水平的指标,炉龄的提高表明电炉采用热装脱磷铁水冶炼不锈钢母液工艺日渐成熟。     

Some Problems of Recycling Industrial Materials

The industrial system should learn from the natural ecosystem. The resource utilization efficiency should be increased and the environmental load should be decreased, depending on the materials recycled in the system. The classification of industrial materials from the viewpoint of large-scale recycling was stated. Recycling of materials, on three different levels, was introduced in the industrial system. The metal flow diagram in the life cycle of products, in the case of no materials recycled, materials partially recycled, and materials completely recycled, was given. The natural resource conservation and the waste emission reduction were analyzed under the condition of materials completely recycled. The expressions for the relation between resource efficiency and material recycling rate, and the relation between eco-efficiency and material recycling rate were derived, and the curves describing the relationship between them were protracted. The diagram of iron flow in the life cycle of iron and steel products in China, in 2001, was given, and the iron resource efficiency, material recycling rate, and iron eco-efficiency were analyzed. The variation of iron resource efficiency with the material recycling rate was analyzed for two different production ratios.     

Small Punch Creep Studies for Optimization of Nitrogen Content in 316LN SS for Enhanced Creep Resistance

Small punch creep (SPC) studies have been carried out to evaluate the creep properties of 316LN stainless steel (SS) at 923 K (650 °C) at various stress levels. The results have been compared with uniaxial creep rupture data obtained from conventional creep tests. The minimum deflection rate was found to obey Norton power law. SPC rupture life was correlated with uniaxial creep rupture life. The influence of nitrogen content on the creep rupture properties of 316LN SS was investigated in the range of 0.07 to 0.14 wt pct. SPC rupture life increased and the minimum deflection rate decreased with the increase in nitrogen content. The trends were found to be in agreement with the results obtained from uniaxial creep rupture tests. These studies have established that SPC is a fast and reliable technique to screen creep properties of different experimental heats of materials for optimizing the chemical composition for developing creep-resistant materials.     

焦炉维修材料-磷酸料的改进及应用

介绍了薛城焦化厂焦炉热修补使用的不定型耐火材料及结合剂的种类、配比进行改进的情况。改进后减少了维修次数，延长了维修周期及焦炉使用寿命。     

Expansion of a pair of dissimilar metal shells in lined-pipe production

Globally, the working life of metallurgical products is being increased. To that end, a promising approach is the use of laminar composites. In particular, experience shows that the working life may be greatly increased by using bimetallic and lined pipe instead of monometallic pipe. Lined pipe is bimetallic pipe produced by the expansion of coaxial shells made from different materials. Little attention has been paid to lined pipe in the literature on the production of composite and bimetallic pipe. The shaping methods used in the manufacturing of lined pipe differ from those for other bimetallic pipe. These differences must be taken into account in the development of lining technologies. The lack of information regarding the shaping of the shells in lining complicates the machining of lined pipe. Therefore, the present research is devoted to the deformation and shaping of paired coaxial shells and the nonuniform strain distribution between the inner and outer shells in the lining process, as well as the influence of these factors on the ratio of strength properties of the materials in the lined pipe produced.     

武钢CSP加热炉内衬的优化设计

武钢CSP加热炉炉衬较薄,使用全纤维模块砌筑,其隔热性能好,但使用寿命较短。在保证炉衬厚度不增加、隔热效果不降低的前提下,通过传热计算对炉衬材料进行了优化设计。耐火层选用浇注料延长使用寿命,分析了隔热层分别采用纤维毡、纳米隔热板、超级憎水隔热板等不同隔热材料对外表温度与散热量的影响,确定了合理的材料组成,达到了既能延长使用寿命,又能降低成本的目的。     

钢纤维混凝土在南钢大道工程中的应用

钢纤维混凝土是一种性能优良的新型复合材料，与普通混凝土相比，其抗拉、抗弯、抗裂及耐磨、耐冲击、耐疲劳等性能都有显著提高，它不仅可使路面厚度减薄，工程缝间距加大，改善路面的使用性能，延长路面使用寿命，而且还可节省工程造价，缩短施工工期。文中结合南钢大道路面工程实际，主要介绍了钢纤维混凝土的施工及质量控制要点。     

The effect of matrix microstructure on cyclic response and fatigue behavior of particle- reinforced 2219 aluminum: Part I. room temperature behavior

The low-cycle and high-cycle fatigue behavior and cyclic response of naturally aged and overaged 2219/TiC/15p and unreinforced 2219 Al were investigated using plastic strain-controlled and stress-controlled testing. In addition, the influence of grain size on the particle-reinforced materials was examined. In both reinforced and unreinforced materials, the naturally aged conditions were cyclically unstable, exhibiting an initial hardening behavior followed by an extended region of cyclic stability and ultimately a softening region. The overaged reinforced material was cyclically stable for the plastic strains examined, while the overaged unreinforced material exhibited cyclic hardening at plastic strains greater than 2.5 × 10⁻⁴. Decreasing grain size of particle-reinforced materials modestly increased the cyclic flow stress of both naturally aged and overaged materials. Reinforced and unreinforced materials exhibited similar fatigue life behaviors; however, the reinforced and unreinforced naturally aged materials had superior fatigue lives in comparison to the overaged materials. Grain size had no effect on the fatigue life behavior of the particle-reinforced materials. The fatigue lives were strongly influenced by the presence of clusters of TiC particles and exogenous Al₃Ti intermetallics. formerly Research Assistant with the Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI 48109 This article is based on a presentation made in the symposium entitled “Creep and Fatigue in Metal Matrix Composites” at the 1994 TMS/ASM Spring meeting, held February 28–March 3, 1994 in San Francisco, California, under the auspices of the Joint TMS-SMD/ASM-MSD Composite Materials Committee.     

大型高炉出铁沟用耐火材料的研究与应用

对大型高炉出铁沟用浇注料、捣打料、喷补料的性能进行了研究，分析了材料的性能、施工工艺与使用寿命的关系，认为适当的维护对于降低成本、提高寿命是有益的，铁厂需要合理的考虑使用寿命与材料的价格因素。     

降低150t转炉半钢炼钢留渣操作实践

承钢150 t转炉半钢冶炼采用留渣操作,通过终点成分分析和开吹前炉底铺加石灰、白云石等措施,取得了良好的脱硫脱磷效果,同时保护了炉衬、节约了原辅料、降低了生产成本,转炉炉龄提高到7 000炉,没有发生喷溅等安全事故。     

挤压法制取银-石墨纤维型触头材料

本文介绍了一种新型的银-石墨纤维型触头材料。叙述了它的挤压、切片、脱碳等工艺。与常规工艺制取的材料相比,该材料不但物理性能、电寿命大为提高,而且保持了抗熔焊性好的优点。对于既要求有可靠的抗熔焊性又要求有较长电寿命的自动开关。是较为理想的触头材料。由于电寿命提高和触头尺寸减小,节银效果明显。     

基于磁特性的铁磁材料疲劳寿命的预测

研究了铁磁材料在疲劳过程中磁导率的变化与疲劳寿命间的对应关系，建立了预测疲劳寿命的人工神经网络模型，它可用于估算材料的疲劳损伤程度，预测材料的疲劳寿命。     

精密金属铰链材料所用异型模具的研究

介绍了眼镜行业用金属异型材料生产中所用挤压模和拉拔模在不改变模具材料的情况下,对其结构及制模工艺进行改进的一些措施。通过实践证明提高了产品成材率,延长了模具寿命,对异型模具设计具有现实意义。     

Intimate justice: confronting issues of accountability, respect, and freedom in treatment for abuse and violence

Comparisons of nationally representative survey data of the population ages 18-54 years in 1971 (N = 2252) and 1992 (N = 1718) from Finland show that sexual satisfaction has greatly increased particularly among women. Some predictors of sexual satisfaction of men and women are examined on the basis of the 1992 survey data on people ages 18-74 years (N = 2250). Correlations between social background factors, sexual ideas and assertiveness, optional relationships, sexual practices, organism, and satisfaction with sexual intercourse were calculated. To control the simultaneous effect of the variables explaining satisfaction, path analyses were conducted. Results show that young age, a sexually unreserved and a nonreligious childhood home, early start of sexual life, high education, sexual assertiveness, considering sexuality important in life, reciprocal feeling of love, use of sex materials, frequent intercourse, many-sided (versatile) sexual techniques, and frequent orgasm correlate with finding sexual intercourse pleasurable. There were some gender differences in the connections between the independent factors and satisfaction with coitus. The importance of sexuality in life, love, and the use of sexual materials were connected directly to physical sexual satisfaction among men but only indirectly among women. For women, but not for men, young age and early start of sexual life correlated with enjoyment of intercourse. The greater sexual dissatisfaction of women compared to men, which still prevails, may be due to their late start of sexual life, conservative sexual attitudes, unimportance of sexuality in life, lack of sexual assertiveness, and use of restricted sexual techniques. The emancipation of women may change these ideas and practices of women. This might lessen the gender gap in physical sexual satisfaction.     

含铝冷镦钢塞棒侵蚀原因分析与改进

 针对含铝冷镦钢在浇铸过程中的塞棒异常侵蚀问题,通过塞棒基体成分分析、塞棒侵蚀层的元素分布观察以及热力学计算,探究了含铝冷镦钢生产过程中塞棒侵蚀的成因,并提出相应的改善措施。结果表明,钢中高质量分数的钙与耐火材料中的Al2O3、SiO2、C发生反应,生成低熔点钙铝酸盐或硅铝酸盐以及Al2O3-C质塞棒本身材质中C＋SiC的质量分数过高是造成含铝冷镦钢浇铸过程中塞棒严重侵蚀的主要原因,通过规范钙处理工艺、更换镁碳质塞棒等措施,能够显著改善塞棒的异常侵蚀问题,塞棒的使用寿命由286～824 min提升至460～1 020 min,平均使用寿命由原来的495 min上升至802 min。