Acoustic emission studies of electron beam surface modification of aluminum

Acoustic emission from carefully designed stationary pulsed electron beam heating experiments has been monitored in pure Al and a binary Al-4.5 wt pct Cu alloy to explore the use of this technique forin situ characterization of surface modification. A three-fold correlation was made among heat flow theory, acoustic emission, and post-solidification metallographic observations. By calibrating the acoustic emission system, it has been possible to deduce the dipole strength of the sources responsible for acoustic emission. Comparison with estimated values for candidate sources during surface modification indicates that only slip (in coarse grained material) and microfracture (in the alloy) are detectable. Their incidence during a thermal cycle reflects the evolution of thermal and solidification stresses accompanying surface modification. It has been found that cracking in Al-4.5 wt pct Cu alloys is a significant source of acoustic emission. The incidence of cracking has been found to depend upon the substrate properties. Soft, underaged material cracks significantly less than peak-aged material, suggesting that the contraction stresses responsible for cracking can be accommodated by adjacent matrix slip in underaged samples.     

Acoustic emission studies of electron beam surface modification of aluminum

Acoustic emission from carefully designed stationary pulsed electron beam heating experiments has been monitored in pure Al and a binary Al-4.5 wt pct Cu alloy to explore the use of this technique forin situ characterization of surface modification. A three-fold correlation was made among heat flow theory, acoustic emission, and post-solidification metallographic observations. By calibrating the acoustic emission system, it has been possible to deduce the dipole strength of the sources responsible for acoustic emission. Comparison with estimated values for candidate sources during surface modification indicates that only slip (in coarse grained material) and microfracture (in the alloy) are detectable. Their incidence during a thermal cycle reflects the evolution of thermal and solidification stresses accompanying surface modification. It has been found that cracking in Al-4.5 wt pct Cu alloys is a significant source of acoustic emission. The incidence of cracking has been found to depend upon the substrate properties. Soft, underaged material cracks significantly less than peak-aged material, suggesting that the contraction stresses responsible for cracking can be accommodated by adjacent matrix slip in underaged samples.     

Structure and properties of a sintered bronze-graphite antifriction material

Conclusions The results of this investigation show that tin, on dissolving in copper, increases its hardness; the carbon of graphite reduces copper oxides and inhibits grain growth; lead, being in the liquid state during sintering, promotes grain growth and increases porosity. Tin, on reacting with copper, lead, and graphite, cements them into a single, strong conglomerate satisfying the requirements for antifriction materials. By adding 24 vol.% of graphite and lead to copper and ensuring good contact between these additions and the matrix, an alloy has been produced possessing satisfactory frictional and wear properties.Translated from Poroshkovaya Metallurgiya, No. 6(222), pp. 48–53, June, 1981.     

Electron beam scanner and thoracic transplantation

To follow an heart transplantation, EBCT is more precise than ultrasonography and scintigraphy to calculate a stroke volume. In lung transplantation, it is important before surgery to know the value of right ventricule stroke volume in order to choice the surgical protocol. After lung transplantation SFE helps to follow the patient to look after complications, to drain a collection or to guide a biopsy. SFE contribution is discussed in rejection, infectious diseases, detection of immuno-induced carcinomas, in bronchiolitis obliterans and recurrence of the primitive disease.     

H型连铸坯表面温度评析

采用CIT-M型红外测温线性化传感器,测定马钢SS400异型坯在连铸过程中的表面温度;Gleeble-2000热力模拟试验机测定SS400的高温塑性.结果表明:SS400异型坯表面温度在二冷区和矫直时大部分处于低温脆性区760-880℃,铸坯的表面塑性较差;同时,由于二冷2段支撑辊间间隔喷水,铸坯表面温度回复大,远大于连铸二冷配水冶金规则所允许的最大幅度100℃·m^-1.     

Experience with the production of bronze-graphite strip by powder rolling

Conclusions The authors consider some problems involved in the forming of copper-tin-graphite powder mixtures by rolling, as well as the technological aspects of bronze-graphite strip production.Translated from Poroshkovaya Metallurgiya, No. 12, pp. 9–14, December, 1966.     

Electron microscopy of failure in a fibrous composite material based on a glass ceramic

A study is made on the features of failure in a fibrous composite material in relation to the volume proportion of reinforcement. Fractographic analysis shows that failure in such a material begins at the matrix-fiber interfaces and is independent of the volume proportion of reinforcing phase, being distinguished by fracture crack propagation occurring in concentric regions of tensile stresses and involving brittle failure in the glass-ceramic matrix. The failure rate at the matrix-fiber interfaces is related to the adhesive strength of the glass ceramic-stainless steel system and the cohesive strength and dissipativeness of the glass-ceramic matrix, and it alters substantially as the volume proportion of the reinforcement increases.Materials Science Institute, National Academy of Sciences of the Ukraine, Kiev. Translated from Poroshkovaya Metallurgiya, Nos. 1/2(383), pp. 86–92. January–February, 1996. Original article submitted January 25, 1994.     

双蓄热步进梁式加热炉的技术改造

介绍了福建三钢棒材厂蓄热式加热炉的改造方案及应用情况,采用两座双蓄热步进梁式加热炉解决了加热炉制约轧机能力提升瓶颈及冷热坯混装的问题,改造后取得了很好的经济效益。     

Prediction of effective elasticity moduli of porous composite materials

A method for calculating the effective elasticity moduli of porous composite materials is committed. Its distinctive feature is in calculating the elasticity moduli of the composite solid phase through the effective volume averaging of component deformations. Analytical dependences for calculating effective deformation volume averaging of the solid phase and its components are presented. The results of a calculation of the macroscopic Young modulus of porous composites agrees well with the experimental data.     

Methods of investigating porous filter materials by scanning electron beam

Translated from Poroshkovaya Metallurgiya, No. 2(314), pp. 52–56, February, 1989.