晶体和多晶体金属塑性变形的非Schmid效应和双剪应力准则

本文将宏观双剪应力屈服准则推广到晶体及多晶体金属的塑性变形,提出了与之相应的晶体临界双剪应力准则,从力学理论上解释了晶体滑移的非Schmid效应。     

Microstructure Variation and Hardness Diminution During Low Cycle Fatigue of 55NiCrMoV7 Steel

 The influence of temperature and hardness level on the cyclic behavior of 55NiCrMoV7 steel, and the microstructure variation and hardness diminution during low cycle fatigue behavior were investigated. By means of SEM and XRD, the modality of carbides and the full width half maximum (FWHM) of martensite (211) [M(211)] of X ray diffraction spectrum in fatigue specimen were studied. The results showed that the cyclic stress response behavior generally showed an initial exponential softening for the first few cycles, followed by a gradual softening without cyclic softening saturation. The fatigue behavior of the steel is closely related to the hardness level. The hardness diminution and the variation of half width M(211) are remarkably influenced by the interaction between the cyclic plastic deformation and the thermal loading when the fatigue temperature exceeds the tempering temperature of the steel.     

A method of beam combination of high- power incoherent fiber laser

Diffraction efficiency of grating plays an important role in output power of incoherent fiber laser beam combination. Through theoretic analysis and numerical simulations it has been proved that the diffraction efficiency would increase with the decrease of grating frequency and wavelength bandwidth. On the condition that the width of a fiber array is fixed at W=10 cm, an optimum grating frequency were numerically simulated as f=230 mm-1. Also an unequal interval method was proposed to improve the system efficiency of diffraction into 0.4293, which is higher than 0.3824 under the equal interval condition.     

Electrorheological Particles Composed of Polyaniline Core and BaTiO3 Layer Shell

Composite particles consisting of polyaniline(Pan )core and barium titanate(BaTiO3) layer shell were synthesized. The PAn-BaTiO3 composites particles were characterized with TEM and XRD. The dielectric behavior of particles was tested and the electrorheological (ER) behavior of the suspensions of PAn/BaTiO3 parti-cles in chlorinated paraffin oil with a 20vol% was investigated under DC electric field.The results show that the ER effect of composite particle is far stronger than that of pure polyaniline and barium titanate which were synthe-sized by the same methed. PH and thickness of BaTiO3 have an important influence on the ER effects.     

ICP—AES法测定钢中全铝

本文采用ＩＣＰ－ＡＥＳ法测定钢中合铝，讨论了碱金属离子对ＩＣＰ光谱仪工作的影响及其人他各种光谱线干扰和化学干扰，通过实验确定仪器的最佳工作条件，取得较好的精度和重现性，此法测定范围为０．００２％～０．５％。     

Alloying Design for High WearResistant Cast HotForging Die Steels

The alloying design of cast hotforging die steels was analyzed. The relationship of the life of cast hotforging dies with the failure patterns was studied. The thermal wear resistance was believed to be the key property for the alloying design of cast hotforging die steels. The alloying design parameters were selected and optimized for the cast hotforging die steel with high wear resistance. The wear resistance of the optimized cast die steel was evaluated in comparison with commercial H13 steels and 3Cr2W8V steel. In the new cast hotforging die steel, VC is predominant carbide with Cr and Mo as the main solution elements in αFe. It is found that the cast die steel has significantly lower wear rate than normal H13 steel and 3Cr2W8V steel, almost the same as that of high purity H13 steel. The high wear resistance of the new cast hotforging die steel can be attributed to its reasonable alloying design and nonsensibility to the detrimental function of S and P.     

Fatigue Strength Improvement of Welded Joint by Ultrasonic Peening in Ultra-Fine Grain Steel

Thefatiguestrengthisthemostimportantser vicepropertyofaweldedjoint .Duetotheexistenceoftensileresidualstressesand geometricaldisconti nuityacrosstheweld ,thefailurenormallyoccursattheweldedjoint .Hence ,itiscommonforimportantstructurestoapplyastressrelievingheattreatmentafterwelding .Thisis ,however ,prohibitedforweldedjointsinultra finegrainsteels .Thegrainre finementistheonlystrengtheningmethodthaten hancesbothstrengthandtoughness .IntheNationalKeyFundamentalResearchDevelopmentProject“th…     

地下室超长剪力墙体裂缝成因分析与控制措施

本文结合工程实例,详细分析了地下室混凝土剪力墙体裂缝产生的原因,并在混凝土结构最大允许整浇长度计算分析的基础上,对避免出现地下室超长墙体温度变形裂缝的控制措施与施工养护进行了详细探讨,可为类似工程提供借鉴参考。