介质流速对在线焊接管道极限压力的影响

运用有限元法对不同介质流速下在线焊接时的温度场进行了数值模拟,内部介质流动对焊接温度场的影响通过确定介质与管壁的换热系数来考虑;根据温度计算结果,获得管道的剩余强度因子,进而判定管壁是否烧穿。研究表明,随着流速的增大,焊缝位置处外壁上的峰值温度无明显变化,而内壁上的峰值温度随之下降;在线焊接管道的剩余强度因子及所能承受的极限压力呈上升趋势,且在一定范围内增大明显,故应充分利用该流速变化范围的特点以确定最佳施工条件。     

大功率半导体激光熔覆高速钢研究

使用2kW半导体激光在工具钢表面熔覆高速钢粉末。在同轴送粉的粉末汇聚点与激光的聚焦点可获得无裂纹的熔覆层。随着激光功率的增加,熔覆层厚度和粉末利用率增加,同时基体对熔覆层的稀释率下降。获得的熔覆层的硬度达到800Hv0.3,基体硬度200Hv0.3,表明大功率半导体激光在表面熔覆领域具有很好的应用前景。     

珠光体球化的分形研究

珠光体球化反映到金相上，是一种不规则图像的变化，并且具有分形的特征，可望用分形几何的方法来进行描述。以Cr-Mo钢的珠光体球化为例，用分形维数来描述珠光体球化程度；用小岛法对15CrMo钢的珠光体球化图谱进行了测量。实验表明，珠光体球化从1级到6级，其相应的分形维数范围为1.3156-1.9282。从电厂运行了10^5h的15CrMo钢管上取样，实测了该试样的珠光体球化等级，结果表明，以分形维数表示的球化程度与按图谱评定的球化等级完全吻合。     

热作模具钢表面激光堆焊耐磨合金层的研究

本文主要通过在H13钢上用大功率CO_2激光束进行堆焊,阐述了激光堆焊工艺变化对堆焊组织和性能的影响,在本试验条件下,得到了高密度弥散金属化合物组织的激光堆焊层,平均硬度为HV800,与基体呈冶金结合,耐磨性比H13模具钢提高149%。     

Process monitoring using auto-associative,feed-forward artificial neural networks

The potential of using artificially simulated neural networks as intelligent, adaptive process-monitoring devices is discussed. The investigation is considered as a method for automatic, intelligent exception reporting for quality control applications. The technique is also compared with the conventional statistical approaches of principal component analysis and Kohonen's feature map. The applications of the technique in aerospace and manufacturing environments are presented and a possible extension of the method to incorporate a diagnostic function is discussed.Seconded from Cheltenham and Gloucester College of Higher Education as a Royal Society/SERC Research Fellow at Smith's Industries Aerospace and Defence Systems, Bishop's Cleeve, Cheltenham, UK.     

浅谈无缝钢管的壁厚偏差

通过探讨、分析无缝钢管壁厚偏差产生的原因，提出了改善钢管壁厚偏差的一些措施，并结合实际生产，得出了比较满意的结果。     

粗粒土渗透变形机制浅析

对砂卵砾石的渗透变形的形成条件进行了简要分析，在此基础上对渗透变形的形式进行了简要评价，并提出了渗透变形临界坡降的计算方法。     

Quantitative feedback theory with applications in welding

Two different control systems were developed using quantitative feedback theory for weld quality improvement. The first application to be discussed was designed for the resistance pinch welding process and uses electrode displacement and force as feedback parameters. A correlation between weld quality and electrode displacement is established for constant electrode force. The system is capable of producing repeatable welds of consistent quality, with wide variations in weld parameters. This is the first time feedback control has been successfully applied to pinch welding. The second example presented in this paper was developed for penetration control of the gas-tungsten-arc welding process. The feedback signal is obtained by measuring the amount of light emitted from the back side of the weld. Welds of constant penetration have been demonstrated in tests with travel speeds varying from 1.5 to 6 inches per minute and with 200 per cent changes in part thickness.     

18Ni（350）马氏体时效钢的磁滞特性

采用双时效处理工艺研究了热轧１８Ｎｉ（３５０）马氏体时效钢的磁滞特性。结果表明，８２０℃·　ｈＡＣ＋（５９－６１０）·。ｈＡＣ＋５１０℃·。ｈＡＣ和８２０℃·　ｈＡＣ＋（６９０－７１０℃）·３ｈＡＣ＋１５０℃·３ｈＡＣ处理具有较高的磁滞性能，在对大量数据进行二元线性回归的基础上得出了１８Ｎｉ（３５０）马氏体时效钢磁滞特性的分段关系式。