Computer Simulation of the Process of Quenching Large-Size Parts in Water and Aqueous Solutions

DESPITE of the rapid development of computerfacilities and numerical methods of computing thestress-strain state of large-size parts,the accuracy ofcomputations is not sufficient because of the lack ofaccurate input data.For this reason,heat treatingengineers do not trust computations and are afraid ofquenching of large-size parts in water,in particular,when Bi—>°°.There are some causes of suchsituation:1)Because of inaccurate boundary conditions andincomplete information on mechanical p…     

Rheologic behaviors of A356 aluminum alloy billet produced by semisolid continuous casting process

The experiments for rheologic behaviors of semisolid continuous casting billets of A356 alloy in semisolid state had been carried out with a multifunctional rheometer. The results show that the deformation rate increases with loading time, the maximum strain reaches to 120％ (which is one time larger than that of traditional mold casting billet) and the strain can be rapidly eliminated to 10％ after unloading. Moreover, there is a critic stress for billet deformation even in semisolid state, which is named as critic shear stress. This stress increases with the decreasing of heating time. The theologic behaviors can be expressed by five elements mechanical model (H_2- [N_1|H_2]-[N_2|S]) and can be modified with the increasing of heating time.     

被加热零件在炉内的合理布局

对各种零件、金属型材、管材、金属粉末材料热处理的使用经验和炉子计算的结果表明,工件在炉膛内布局方法的选择,或小零件与金属粉末层厚度的选择,在很多情况下,都将对炉子的技术经济指标产生显著的影响。为了考察这种影响,对已知工作区宽度与长度(即可安置零件的面积)的连续式电炉进行了研究。此时,采用规定的工艺保温时间。众所周知,在装料时总存在着最好的方案。实践中,实际的装料方法常常与最好的方案有所差异,即还存在着使生产率提高的某些潜力。今用二个实例来说明可能的潜力之大小。例1:拖拉机轴在推杆式电炉中作淬火     

离耐磨性扩散的现状和将来

几年来,华沙精密机械研究所对用来形成高耐磨性扩散渗层的工艺过程作了研究,同时特别着重研究了渗层组织和耐磨性能之间的关系。表1中所列的是不同组织和性能(首先是硬度)的几种典型扩散层。工业上应用最普遍的是渗碳层(近来又应用碳氮共渗散层)。     

Preparation of ultrafine Sb_2O_5 composite powder

ＰＲＥＰＡＲＡＴＩＯＮＯＦＵＬＴＲＡＦＩＮＥＳｂ＿２Ｏ＿３－Ｓｂ＿２Ｏ＿５ＣＯＭＰＯＳＩＴＥＰＯＷＤＥＲＤｕａｎ，Ｘｕｅｃｈｅｎ；Ｚｈａｏ，Ｔｉａｎｃｏｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＮｏｎｆｅｒｅｒｒｏｕｓＭｅｔａｌｌｕｒｇｙ．ＣｅｎｔｒａｌＳｏｕｔ...     

挤压过程的分类

结合近年来理论研究的新进展和新领域实际应用的成就 ,就挤压分类法提出了更准确、更详细、更全面的并有所创新的分类法。     

Recent progress of CERN RD50 Collaboration

The objective of the CERN RD50 Collaboration is to develop radiation hard semiconductor detectors for very high luminosity colliders, in particular, for the upgrade of the large hadron collider （LHC） which itself is scheduled to be operational in 2007. The approach of the RD50 has two major research lines, material engineering and device engineering. These are further subdivided into projects covering defect characterization and engineering, new detector materials, detector characterization, new detector structures and full detector systems. Presently, 264 members from 53 institutes are actively participating in the RD50 Collaboration. Detectors made of defect engineered substrates, e.g. high resistivity magnetic Czochralski （MCz-Si）, epitaxial silicon （Epi-Si） on Czochralski silicon （Cz-Si） substrate, intentionally thermal donor （TD） compensated p-type MCz-Si and oxygen enriched （DOFZ） silicon, have been demonstrated by the RD50 Collaboration. An overview and highlights of the results of these defect engineering techniques were given in this report.     

镁合金新产品

国际镁协会估计西方国家1987年镁产量达到268000吨,为原镁生产能力的88%左右.尽管可能出现少量过剩,一些原镁生产厂认为总产量仍太少.有些生产厂宣布了扩充计划,到1992年,西方国家镁的生产能力将增加100000吨.新增加的产能大多数是在加拿大和美国.     

Fabrication and Characterisation of Rutile-TiO_2 Coatings on Metallic Alloy Substrates

RUTILE-TJO2is a versatile material possessing manyinteresting physical,chemical,optical and dielectricproperties[l].It is also a good tribological material thatcan offer low friction and low wear rate[2,3].However,the application of rutile in the tribological field hasbeen limited to titanium alloys only so far,for example,by thermal oxidation of titanium alloys[4,5].Very fewinvestigations have been directed to the tribologicalapplications of rutile films on substrates other thantitanium al…