Mechanisms of nanostructure and metastable phase formations in the surface melted layers of a HCPEB-treated D2 steel

This work investigates the mechanism of surface modification associated with the high-current pulsed electron beam (HCPEB) treatment of a D2 steel with increasing numbers of pulses. The surface layers were melted and resolidified but the treated surfaces showed very different features. This variation is essentially due to the different levels of homogeneity and carbide dissolution. It is demonstrated that the presence of carbides served as nucleation sites for the surface eruption phenomenon that creates craters on the surface. After a sufficient number of pulses, most of the carbides in the surface layer were dissolved and an almost crater-free homogeneous melted layer consisting of a very stable nano-austenite structure was formed. The HCPEB technique is thus demonstrated to be a versatile technique for surface microstructure modification involving, in the case of steels, austenite stabilization and ultrafine grain formation.     

冷却方式对Zn-Cu包晶合金微观组织的影响

对采用不同冷却速度、不同散热条件的铸型得到的Zn-2.98Cu包晶合金的微观组织进行了研究.研究表明:在常规的砂型和金属型铸锭中,其微观组织为ε相 η相基体;在具有定向温度梯度的铸锭中,得到了定向的ε相枝晶 η相基体和定向的层片状(ε η)组织;并对层片状组织做了进一步分析,得到的Zn-Cu包晶合金层片间距平均值λ=4.06μm.     

升水、贴水(四)

四、品质升、贴水 除了前面介绍的现货与期货、两地之间以及合约之间的升、贴水关系,另外还有品质升、贴水的概念.尽管只有符合交割等级的商品才允许在期货交易所交割,但是在符合交割等级的商品中,由于产地、生产厂家以及技术条件等方面的不同,在交割商品的品质方面还是有一定的差异.因此根据期货交易所条例所允许的,对高于期货合约交割标准的商品所支付的额外费用为品质升水,反之为贴水.     

热连轧冶金过程组织性能预报技术

本文简要介绍了热连轧冶金过程中组织性能预报技术的研究内容和研究方法以及该技术在工业生产中的应用和作用.     

Analysis of deformation texture inhomogeneity and stability condition of shear components in f.c.c. metals

The texture of cold rolled aluminum sheet has been known to vary through the thickness due to inhomogeneous deformation during rolling. The copper texture is obtained in the center layer that is plane strain compressed while the shear texture in the surface layer, which is approximated by major 001 011 and minor 111 112 and 111 110 components. The stability condition of these components was calculated based on the full constraint Taylor-Bishop-Hill theory and could be described by a parameterdɛ₁₃/dɛ₁₁ with the suffixes 1 and 3 indicating the rolling and thickness directions, respectively.     

稀土Ce和Y在ZK60合金中的分布、演变及其对性能的影响

用熔铸法制备了两类8种镁-稀土合金，通过力学性能试验，X射线衍射（XRD）、扫描电子显微（SEM）分析确定了稀土元素Ce、Y在ZK60镁合金中的分布、演化规律及其不同状态时所发挥的作用。结果表明：ZK60-1．5Ce和ZK60-1．0Y分别在两类合金中具有最佳的力学性能；Ce和Y在铸态时都分布在晶界上，在基体镁中的分布极少，经挤压变形后，Ce和Y沿挤压方向分布：无论合金处于什么状态，Ce和Y都以化合物的形式存在为主。试验合金的力学性能都高于ZK60合金本身。     

电液振动台自适应Fuzzy-PI控制器的设计

在离心加速度和振动和振动复合环境中,用于结构振动试验的电液伺服系统是一个时变耦合的非稳定性系统。本文考虑了上述因素,提出了自适应Ｆｕｚｚｙ－ＰＩ控制方法,控制参数可由自适应Ｆｕｚｚｙ－ＰＩ构件进行动态调整,采用模糊法则及ＣＲＩ推理确定参数。本文介绍了控制器的设计方法,并给出了正弦振动加载试验的结果。结果表明控制器较高的稳态精度,动态特性好,自适应能力强。     

NUMERICAL SIMULATION OF CONTROLLING IN TITANIUM ALLOY SHEETS WELDING RESIDUAL STRESS BY TRAILING PEENING

It is a promising and new technology to apply welding with trailing peening to control welding stress and distortion of titanium alloy. Numerical simulation of conventional welding and welding with trailing peening of the titanium alloy sheet is carried out, using nonlinear finite element theory and the engineering analysis software MARC. The result shows that welding with trailing peening technology reduces longitudinal residual stress in welding joint effectively, and it is more effective to reduce residual stress to peen the weld than to peen the weld toe. It is a effective result that other technolooy and method used in welding can never achieved.     

Si纳米纤维的等离子体制备工艺

本文利用电弧等离子体蒸发制备了纳米Ｓｉ纤维，通过沉积温度场的调节，确定了纤维的最佳沉积温度约６００℃，同时表征了纤维的生长过程，在一定的温度下，Ｓｉ团聚体颗粒间的“颈连接”及颗粒表面的非晶层是导致团聚体自扩散和表面扩散一维生长的直接条件。     

时效对接触线用Cu-Ag-Cr合金性能的影响

分析了固溶温度、时效及时效前冷变形量对Cu - 0 1 %Ag - 0 1 %Cr接触线用合金性能的影响 ,结果表明 :经 870℃固溶、 40 %～ 5 0 %冷变形及 480℃× 1 5h时效处理后 ,合金可获得良好的综合性能。