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31.
以热轧板厂粗轧主传动滑块式万向接轴为例,分析了该接轴及接轴平衡机构的常见故障及其排除方法,提出了日常维护措施。 相似文献
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Daljit S. Khurana Kulwant S. Randhawa Krishan L. Bajaj 《Journal of the science of food and agriculture》1985,36(10):959-962
Post harvest application of Isopropyl-N (3-chlorophenyl) carbamate considerably reduced the degradation of starch when potato tubers were stored in an evaporative cooling chamber. The starch degraded at a faster rate when tubers were kept under refrigerated and room storage conditions. 相似文献
34.
M. E. Stevenson S. L. Lowrie R. D. Bowman B. A. Bennett 《Journal of Failure Analysis and Prevention》2002,2(4):55-60
Cold cracking of structural steel weldments is a well-characterized, well-documented, and well-understood failure mechanism.
Extensive effort has been put forth to recognize the welding and materials selection parameters that are conducive to cold
cracking; however, these engineering efforts have not fully eliminated the occurrence of such failures. This article describes
cold cracking failure specifically related to the construction industry. This particular failure was successfully identified
prior to final erection of the structural member, and the weld was successfully reworked. These actions potentially prevented
a serious catastrophic event that could have occurred have occurred either later in the construction process or possibly during
the use of the building. Individual welding parameters, such as electrode/wire selection, joint design, and pre/postheating,
played a role in the failure, and a number of human factors relating to the actual fabrication practices also contributed
to the failure process. 相似文献
35.
Ti-23Al-14Nb-3V合金氩弧焊接头的显微组织及其力学性能 总被引:6,自引:1,他引:5
研究了预热对Ti-23Al-14Nb-3V合金焊接性,特别是对消除氩弧焊冷裂纹的作用以及对接头显微组织和力学性能的影响。结果表明,焊前预热可有效降低该合金的冷裂倾向。经预热处理后,焊缝区的结晶层状线消失,热影响区的硬度峰得到缓和,整个焊缝的显微硬度分布趋于均匀,但焊缝区的枝晶发生粗化,热影响区有所扩大。焊件接头的拉伸试验表明,预热可使焊缝区的接头强度系数增加,但无论预热与否,接头强度均低于母材强度,且不显示宏观塑性。 相似文献
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Low carbon steel was oxidized over the temperature range 1000‐1250°C in O2‐CO2‐H2O‐N2, O2‐H2O‐N2, and O2‐CO2‐N2 gas mixtures. Oxidation times were 12‐120 min. and the scales were 50‐2000 μm thick. The variations of these parameters were chosen to elucidate the phase composition of oxide scales under conditions similar to those of reheating furnaces in hot strip mills, using either thin slab casting or conventional casting and rolling technology. Two types of scales have been observed which are influenced by the furnace atmosphere, oxidation time, and temperature. The first type is a crystalline scale with an irregular outer surface, composed mostly of wustite (FeO), and a negligible amount of magnetite (Fe3O4). The second type is the classical three‐layer scale, composed of wustite (FeO), magnetite (Fe3O4), and hematite (Fe2O3). In general, the experiments showed that an increase in oxidation time decreased the percentage of wustite while the percentages of magnetite and hematite increased. A rise in oxygen concentration in the gas mixture increased the percentages of magnetite and hematite, confirming earlier experimental findings. In water vapour‐free atmospheres O2‐CO2‐N2, the oxide scales had a low percentage of wustite, and high percentage of magnetite and hematite. Carbon dioxide showed a small influence at 1100°C, and a negligible one at 1250°C. 相似文献
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