Cr-W-Mo-V中合金钢的淬火硬度计算及其回火硬度特性

研究了4种不同成分的Cr-W-Mo-V中合金钢的淬火硬度、回火硬度变化和组织结构转变。在淬火基体成分计算的基础上提出了该钢淬火硬度与某一淬火温度下奥氏体基体化学成分关系的近似计算公式。此类钢均具有较高的抗回火性,随着Cr、W、Mo、V含量的增加,不同类型碳化物的沉淀强化可使回火硬度出现低温二次硬化区或平台区,甚至高温二次硬化区。讨论表明,上述淬火硬度计算公式隐含着洛氏硬度测定和马氏体强化机理的对应关系,对其它钢种也适用。

不同味夸克产生的喷注硬度特性的比较研究

用蒙特卡洛模拟方法研究了e+e-对撞Z0强子衰变事件中胶子喷注和夸克喷注的硬度特性.发现夸克喷注和胶子喷注的硬度特性存在较大的差异;不同味的夸克喷注的平均多重数、平均横动量和平均快度随硬度的分布特性也存在明显的差异,而不同味的夸克发射的胶子产生的喷注的硬度特性是一致的;胶子喷注与夸克喷注的平均横动量、平均多重数与硬度之间存在较强的正关联,而平均快度与硬度之间存在较强的负关联.

塑料硬度特性和塑料洛氏硬度的正确应用

一、概述随着塑料工业和新型复合材料生产的发展,以塑代木,以塑代金属,已成为当前各种工业的发展趋向。我国正在试制全塑飞机和全塑汽车,对降低成本,节约触源有着深远的战略意义。硬度是材料试验中最简单、迅速和较易实施的方法。

统计过程控制在大型生产线上的应用

针对汽车安全件物料初加工生产过程中,物料硬度质量监控存在的只关注结果而忽视过程的问题,应用统计过程控制(SPC)技术工具,分析物料硬度过程能力指数等过程稳定性内容。结果表明:物料硬度特性得到明显改善,过程稳定性得到很大提高,说明SPC技术工具对于监控、测量、识别、分析、判断、改善生产过程的质量特性波动和问题趋势,具有一定的实用价值,值得推广和应用。

基于微处理器和PWM的船用大功率直流电机起动与调速研究

采用PWM脉宽调制改变直流电压的控制方式，具有效率高、电压连续可调等优点，已广泛应用于大功率直流电机的调速中。本文对直流电动机调速驱动方式中存在的问题进行了分析，应用微处理器对驱动模块进行适时检测与自动切换，保证驱动系统的工作连续性和安全稳定性；对操作人员非正常操作或误动作产生的错误指令给以合理的修正，提高系统的操作客错与智能型控制能力；同时根据电机有效负载曲线对直流电机的启动、调速实施节能运行管理等。以实现在不改变电动机原有机械特性的条件下达到高效、安全、节能、环保的运行目的。

Weld Characteristics and NC Bending Formability of QSTE340 Welded Tube

The mechanical characteristics of the weld joint were investigated by tensile test, microstructure test, and microhardness test. The welded tube NC bending tests were carried out to evaluate the weld on the formability of the QSTE340 welded tube. The results show that the wall thinning degree, cross-sectional deformation and springback angle increase significantly as the weld line is located on the outside of the bend compared with that located on the middle and inside, and the welded tubes produce nearly identical performance as the weld line is located on the middle and inside. The wall thickening degree decreases much as the weld line is located on the inside of the bend. So the welded tube can acquire good bending formability as the weld line is located in the region away from the outside of the bend.

The Effect of Netting Solidity Ratio and Inclined Angle on the Hydrodynamic Characteristics of Knotless Polyethylene Netting

Knotless polyethylene(PE) netting has been widely used in aquaculture cages and fishing gears, especially in Japan. In this study, the hydrodynamic coefficient of six knotless PE netting panels with different solidity ratios were assessed in a flume tank under various attack angles of netting from 0?(parallel to flow) to 90?(perpendicular to flow) and current speeds from 40 cm s^(-1) to 130 cm s^(-1). It was found that the drag coefficient was related to Reynolds number, solidity ratio and attack angle of netting. The solidity ratio was positively related with drag coefficient for netting panel perpendicular to flow, whereas when setting the netting panel parallel to the flow the opposite result was obtained. For netting panels placed at an angle to the flow, the lift coefficient reached the maximum at an attack angle of 50? and then decreased as the attack angle further increased. The solidity ratio had a dual influence on drag coefficient of inclined netting panels. Compared to result in the literature, the normal drag coefficient of knotless PE netting measured in this study is larger than that of nylon netting or Dyneema netting.

复配亲水胶对低脂白羽鸡肉丸硬度和感官品质的影响

利用魔芋精粉、黄原胶和卡拉胶等亲水胶体改善低脂鸡肉丸的硬度和感官品质,采用单因素筛选和正交试验设计,筛选复配亲水胶的最适添加量和复配比例.结果表明,魔芋精粉、黄原胶、卡拉胶三种亲水胶复配能够有效改善低脂白羽鸡肉丸产品的硬度和感官品质,其中魔芋精粉、黄原胶、卡拉胶的添加量分别为0.3%、0.3%、0.3%,添加比例为1∶1∶1时效果最佳.

Research on the Relationship between Molecular Activity of Additives and Lubricating Performance of Aluminum Rolling Oil

In this paper,an ab initio,local density functional(LDF)method was used to explore the relationship between the molecular properties of additives and the lubricating performance of aluminum rolling oil.The structural properties of butyl stearate,dodecanol,docosanol,and methyl dodecanoate were studied according to the density functional theory.The calculated data showed that the atoms in or around the functional groups might be likely the reacting sites.Because of the different functional groups and structure of ester and alcohol,two types of complex additives,dodecanol and butyl stearate,methyl dodecanoate and butyl stearate,respectively,were chosen for studying their tribological properties and performing aluminum cold rolling experiments.The test results agreed with the calculated results very well.The complex ester,viz.methyl dodecanoate and butyl stearate,had the best lubricating performance with a friction coefficient of 0.084 1 and a permissive-rolling thickness of 0.040 mm as compared with that of dodecanol-butyl stearate-base oil formulation.

Micromorphology of Surface Crusts in the Knersvlakte,South Africa

Soils in the Knersvlakte are particularly prone to crusting and have lower inherent infiltrability than other soils across western southern Africa. Micromorphological techniques were used to examine the structure and porosity of soil crusts in the Knersvlakte to ascertain why crusting is so intense in this region. Quantile regression using boundary lines was employed to examine the relationships between infiltrability and soil properties for all samples （n = 67）. This analysis showed that infiltrability is potentially maximal at low water- dispersible ＇clay plus silt＇ content and low silt content （r^2 = 0.72 and 0.64; respectively, n = 67） （Figure 2）. The strength of crusts, pH, EC, clay mineralogy, and water-dispersible clay, silt and ＇clay plus silt＇ content were compared, and a pore analysis using optical microscopy was undertaken on images of six soil thin sections （n = 6） （circular and parallel polarizers）. Pore analysis was further undertaken on five horizontal slices of equal dimensions taken through each soil thin section. The porosity samples with low infiltrability （〈 100 mm·hr^-1, n = 4） had greater crust strength, lower porosity （both total and in the least porous slice） and greater water-dispersible ＇day plus silt＇ and silt content than the porosity samples with high infiltrability （〉 100mm·hr^-1, n = 2）. The porosity samples with low infiltrability showed a trend of lower pH and greater water dispersible clay percentage. Porosity varied within the porosity samples due to the presence of dense clay/silt bands （〈 0.5 mm in width） with relatively few air vesicles. The porosity samples with horizontal slices of low porosity （but large numbers of air vesicles） had low infiltrability, while those without slices of low porosity （and relatively few air vesicles） had high infiltrability. We conclude that the intense crusting and resultant low infiltrability of soils in the Knersvlakte appears to be related to the formation of thin, dense clay/silt bands in the pedoderm.

A particle-breakage critical state model for rockfill material

Particle breakage has a significant influence on the stress-strain and strength behavior of rockfill material.A breakage critical state theory(BCST)was proposed to describe the evolution of particle breakage.The breakage critical state line in the breakage critical state theory was correlated with the breakage factor,which was fundamentally different from that of the original critical state theory.A simple elastoplastic constitutive model was developed for rockfill in the frame of BCST.An associated flow rule was adopted in this model.Isotropic,contractive and distortional hardening rules were suggested in view of the particle breakage.It was observed that the proposed model could well represent the complex deformation behaviors of rockfill material,such as the strain hardening,post-peak strain softening,volumetric contraction,volumetric expansion,and particle breakage under different initial confining pressures.

Investigation into the tribological behaviors of press hardening steels on the tailored conditions

There has been a growing demand for safety parts with tailored properties in automobile industry.However,the understanding of tribological behavior of press hardening steels(PHS)on the tailored conditions is highly inadequate.The present work aims at creating new knowledge about the tribological characteristics of PHS on the tailored conditions and bridging this existing gap.The paper proposes an improved hot drawing tribo-simulator to simulate the realistic experimental conditions industry.Investigations were carried out on the condition of different initial heating temperatures,tool temperatures,austenitizing temperatures,cooling rates and microstructures.The presented results show that the whole frictional process is divided into three stages for both coated and uncoated steels.The frictional factor changes a lot and the peak value of frictional factor occurs for serious adhesive wear.The frictional factor rises as the tool temperature and austenitizing temperature rise.The surface morphology of tools indicates that the coating adhering to tool gets thicker as the tool temperature increases.With the increase of cooling rate,the frictional factor declines firstly and then rises to some extent.Flat dies with different temperatures are used to form specimens with different microstructures,which also affects the frictional factor and wear.