深拉延值的测定及其在薄板成形中的应用

通过对深拉延试验原理的分析及对深拉延值的测定，分析了深拉延值在汽车专用薄板检测中与rm值和薄板厚度开裂率之间的关系。从而阐明深拉延值可作为评价汽车专用薄板成形性的重要参数。     

扩孔率的测定及在检测中的应用

通过对扩孔试验原理的分析及扩孔率的测定,分析扩孔率在汽车专用薄板检测中与元素总量、薄板厚度、强度、伸长率和n^-值等的对应关系,从而阐明扩孔率可作为评价汽车专用薄板成形性的重要参数。     

应变硬化指数n值的测定和应用

通过对应变硬化指数n值的测定与影响因素的探讨,阐明了应变硬化指数n值可作为评价汽车专用薄板成形性的一个重要参数。为确保数据的精确性,最好用七点法进行测试。     

两种方法测定冷轧薄板应变硬化指数、塑性应变比值和伸长率的结果比较

借助两种不同的方法，测定了冷轧薄板的应变硬化指数（n）、塑性应变比（r）值和伸长率。在GALDABINI SUN1000试验机上，用光学非接触引伸计在GRAPHWORK 1软件上实现冷轧薄板的n和r值及伸长率的自动测量；在INSTRON1186试验机上，用YYU5050引伸计在LZC软件上自动测量冷轧薄板的n值，手工测量r值和伸长率。将两种方法得到的试验结果进行比较，发现两种方法的结果非常接受。用光学非接触引伸计在GRAPHWORK1软件上自动测量的n和r值及伸长率具有较高的可靠性和重现性。     

锥杯试验在汽车深冲钢板成形性能评价方面的应用研究

通过对几种汽车用钢板的实验研究总结了锥杯值与薄板的顶压值、rm值、n值、屈服点和抗拉强度的对应关系,阐述了锥杯试验方法在汽车深中钢板成形性评价方面的意义,以及对于实际生产的指导作用.     

汽车薄板拉-压高周疲劳试样的形状和尺寸选取

针对两种不同强度级别、不同厚度的汽车薄板材料,设计出不同试验段宽度、不同平行长度、不同圆弧半径的疲劳试样,在不使用防屈曲装置的情况下,进行不同应力水平、应力比R=-1的高周疲劳试验,并通过相同应力循环形式下不同尺寸试样的疲劳寿命循环次数,来确定汽车薄板材料疲劳试样的形状和尺寸。结果表明:对于厚度0.8～3 mm的汽车薄板,等截面疲劳试样比圆弧形疲劳试样更适合进行汽车薄板拉-压高周疲劳试验,推荐的等截面疲劳试样尺寸(a为试样厚度)为试验段宽度b=(1～3)a,试样平行长度L_c=(1～3)b,圆弧半径r=(3～10)a。     

影响冷轧薄板力学性能测试结果的试验研究

应用INSTRON5569型电子拉力试验机，在不同测试条件下，对冷轧薄板力学性能进行了测试分析。结果表明，设置试验机的控制参数、拉伸速度和试样尺寸等均对力学性能测试结果有影响。提高拉伸速度使规定非比例伸长应力σ0.2增加，应变硬化指数n值减小，塑性应变比r值无明显变化；试样尺寸对r值有影响；建立了不同试样尺寸之间δ值的换算关系。     

基于数字散斑应变测量法的薄板各向异性力学性能研究

系统地说明了采用数字散斑相关法研究薄板各向异性的实验方法和数据处理方法,进而对SPCC钢板和AA6061铝板的各向异性及其演化规律进行了研究。结果表明:散斑应变测量法是一种获取薄板力学性能的有效手段,其最大优点在于能够获得变形过程中的整体应变场,这是研究复杂加载条件下材料力学性能的关键;对于SPCC钢板,其流动应力的各向异性并不严重,但全量和增量形式的Lankford系数(r值和r′值)均表现出了明显的各向异性,且其值随着变形的增加而逐渐降低,这与传统的采用引伸计进行应变测量时只能获得恒定的Lankford系数不同;对于AA6061铝板,其流动应力和r值的各向异性均不明显,但与轧制方向成不同角度试样的伸长率表现出了明显的差异,并且流动应力的加工硬化速率和r′值在拉伸真实应变处于0.15～0.20时出现了剧烈的波动;随着变形的增加,两种薄板应变的各向异性都逐渐增强,SPCC钢板增强得更为明显。     

三种方法测定金属薄板塑性应变比值的结果比较

分别采用半自动、全自动以及光学非接触式引伸计三种不同的方法,测定了四种不同厚度规格的DC03冷轧薄板的塑性应变比(r)值,将三种方法测定得到的试验结果进行比较,发现存在较大差异,进而分析了造成差异的原因.结果表明:半自动法测定的r值与光学非接触式引伸计法测定的r值较接近,试验结果具有较高的可靠性和重现性;而全自动法测定...     

尽快完善汽车专用仪器的计量检定工作

汽车工业中可能出现的量值不准确、不统一等问题将会影响和制约汽车产品的质量和汽车科研的进步。因此，研究和尽快完善汽车专用仪器（计量器具）的计量检定及管理工作势在必行。１汽车专用仪器计量检定的特殊性和必要性汽车工业企业在产品试制、工装模具制作、工艺验证、机械加工与维修、质量检验中的长度测量和精密测量的量值，能通过各级计量机构较好地溯源到国家基准。但目前大部分汽车工业企业的汽车专用测试仪器还未纳入计量管理的轨道。原因是汽车专用仪器属于多参数的测试仪器，涉及到长度、力学、热学、电、时间、频率、光学。声学…     

金属材料塑性应变比r值的测试

ISO10113：2006及GB／T5027-2007规定,对于不均匀塑性应变材料,采用线性拟合回归方法测试塑性应变比,并设定必须通过原点的边界条件。分别采用单点法、过原点线性回归法（设定截距为0）及常规线性回归法（不设定任何边界条件）3种测试方法计算分析了均匀塑性应变材料和不均匀塑性应变材料的r值,并进行比较,探讨了线性回归法设定边界条件的合理性。结果表明：对于均匀塑性应变材料,单点法、过原点线性回归法和常规线性回归法均可准确地分析其r值;对于不均匀塑性应变材料,只能采用常规线性回归法分析其r值,而不能采用单点法和过原点线性回归法分析其r值。     

Ultrasonic Measurement of Sheet Steel Texture and Formability: Comparison with Neutron Diffraction and Mechanical Measurements

Abstract

Ultrasonic measurements were made on a set of thin steel sheets, using the lowest-order shear horizontal mode (SH₀-mode) and lowest-order symmetric Lambwave mode (S₀-mode). The velocities of these modes were measured as a function of angle relative to the sheet rolling direction. From the data reduction it is, in theory, possible to (1) partially characterize the texture of the sheet, and (2) predict the plastic strain ratio (r-value). The plate texture can be completely characterized by quantities known as orientation distribution coefficients (ODCs). The lowest-order ODCs can be obtained from our measurements; these were compared with ODCs measured by neutron diffraction, with good agreement for the dominant ODC. The r-value is a commonly used measure of sheet formability. It is typically measured mechanically with uniaxial tension specimens subjected to large plastic strain. Therefore, the r-value test is destructive and time consuming. We found a good correlation between S₀-mode velocity measurements and r, the average in-plane r-value. Consequently, the use of noncontacting electromagnetic-acoustic transducers (EMATs) may offer an online nondestructive measurement of sheet formability.     

Ultrasonic measurement of sheet steel texture and formability: Comparison with neutron diffraction and mechanical measurements

Ultrasonic measurements were made on a set of thin steel sheets, using the lowest-order shear horizontal mode (SH₀-mode) and lowest-order symmetric Lambwave mode (S₀-mode). The velocities of these modes were measured as a function of angle relative to the sheet rolling direction. From the data reduction it is, in theory, possible to (1) partially characterize the texture of the sheet, and (2) predict the plastic strain ratio (r-value). The plate texture can be completely characterized by quantities known as orientation distribution coefficients (ODCs). The lowest-order ODCs can be obtained from our measurements; these were compared with ODCs measured by neutron diffraction, with good agreement for the dominant ODC. The r-value is a commonly used measure of sheet formability. It is typically measured mechanically with uniaxial tension specimens subjected to large plastic strain. Therefore, the r-value test is destructive and time consuming. We found a good correlation between S₀-mode velocity measurements and , the average in-plane r-value. Consequently, the use of noncontacting electromagnetic-acoustic transducers (EMATs) may offer an online nondestructive measurement of sheet formability.Contribution of U.S. Department of Commerce, National Institute of Standards and Technology; not subject to copyright.     

热轧工艺对Cr12钢表面起皱的影响机制

研究了热轧工艺对Cr12钢表面起皱相关的组织和织构演变的影响,重点关注其对变形组织不均匀和晶粒簇形成的改变。结果表明：随着热轧终轧温度由960降低到850℃,在变形组织中带状晶粒减薄,剪切变形比重增大,含有剪切带的晶粒增多,由表层向中心层逼近,中心层附近光滑带状晶粒减少;在退火组织中由含有剪切带晶粒形成的高r值晶粒簇增...     

Influence of grain size on plastic anisotropy in low-carbon steels

Abstract

The plastic anisotropy of textured polycrystalline materials has often been described by the r-value – the ratio of the width and thickness strains. The measured –-values of low-carbon steels for larger grain sizes are found to agree reasonably well with values calculated by the authors on the basis of the Taylor theory. In steels with small grain sizes the absolute level of r-value is not predicted particularly well, but the variation with testing direction (planar anisotropy) is predicted well. Calculations showed that in all cases the instantaneous anisotropy parameter ρ as a function of strain, when extrapolated to zero strain, agreed with the value predicted from the measured texture. With small grain sizes a sudden drop in ρ was observed with increasing strain, this being complete within 2–3% of strain. The influence of grain size on the plastic anisotropy can be understood if it is assumed that the grain boundary resistance parameter K in the Hall–Petch relation depends on the contraction ratio – in a different way from the Taylor factor M(q). Measurements of the Hall–Petch constant in plane-strain compression support this view.

MST/84     

卷取温度、冷轧总变形量对SPHD钢力学性能的影响

以CSP工艺在不同卷取温度下生产的冷轧基板SPHD为实验材料,采用不同的冷轧总变形量进行冷轧并退火。通过单向拉伸实验对不同工艺条件下试样的基本成形性能指标（r值、n值）和力学性能指标（屈服强度、抗拉强度、伸长率）进行测定,并对退火试样进行X射线织构测试分析。通过对比分析发现,当卷取温度为600℃,冷轧压下量为70％时,SPHD退火后会得到较强的γ纤维织构组分和良好的力学性能及优异的冲压性能。     

A viscous pressure bulge test for the determination of a plastic hardening curve and equibiaxial material data

The importance of an accurate material modeling for the accuracy and reliability of sheet forming simulations has become increasingly evident during the last years. More advanced material models have, however, to be supported by novel methods for material characterization. The recent eight parameter yield functions Yld2000-2d and BBC2003 demand, besides data from the ordinary uniaxial tensile tests, also equibiaxial data. In the present paper a Viscous Pressure Bulge (VPB) test is described. The test yields the equibiaxial stress point and r-value, as well as a plastic hardening curve for large values of plastic strain. The test setup is based on an ARGUSS? optical measuring system, and provides the desired result data in a very smooth and easy way. In order to verify the results from the current test, comparisons have been made with compression tests performed at Corus RD&T and hydraulic bulging tests performed at RWTH in Aachen. A discussion on how to determine the equibiaxial yield stress and how to transform the biaxial stress-strain curve to an effective stress-strain curve is included in the paper.     

On the Method of Determination of the Noise Levels of Black-and-White Photographic Materials

According to the recent studies on the noise characteristics of photographic materials, two kinds of noise can be defined: the macronoise, trD (mac), and the micronoise, aD (mic). The macronoise is the equivalent of the RMS-granularity of the photographic material, and is believed to include the contribution of the macroscopic non-uniformity of the emulsion layer. On the other hand, the micronoise is thought to be determined by the ultimate limits of the statistical fluctuation in the process of photon recoding on the emulsion layer. In this work, the above mentioned hypothesis was verified experimentally and also by computer simulation. The results showed that σ_D (mac) is generally greater than σ_D (mic), and the standard correlation coefficient, r, is greater than zero. This is obviously not due to the overlapping of the successive sampling spots. When the sampling rate was reduced from 50 s^-l to 11 s^-1 which is equivalent to increase the distance between the successive sampling spots from 52.4 microns to 238 microns, the macronoise remained unchanged, whereas the micronoise became close or equal to the macronoise. The computer simulation showed that the micronoise approaches the macronoise as the distance between the successive sampling spots increases. The authors suggested that the macronoise, i.e. the RMS-granularity, can be used as a figure of merit in the evaluation of photographic materials, whereas the micronoise may be more meaningful when one’s interest is on the influence of AgX emulsion on the image quality. The r-value may serve as a measure of the large-scale non-uniformity of a photographic layer.     

Environmental liability and life-cycle management of used lubricating oils

Used oil handling, as a business, requires an extensive understanding by management that environmental liabilities exist through its supply chain. Findings from a review of the legal requirements of operating a used oil handling business were: understanding the transfer of ownership of used petroleum hydrocarbons is critical to any such business and how this is documented; used oil handlers are responsible for providing training to their staff, including site personnel and any third party waste contractors, and for communicating best practice procedures relating to the management of used petroleum hydrocarbons to all those individuals and organisations involved in business relationships that the used oil handling companies have; used oil handlers should audit the performance of any third party contractors that it engages to conduct work on behalf of its customers. Hypothetical situations of a company planning to enter the used oil handling market are described in relation to petroleum hydrocarbon wastes it handles to illustrate the range of potential liabilities. Companies proposing to establish a used oil handling business should ensure that they provide accurate advice to its employees, its customer's employees and to its third party contractors, all of which may be responsible for handling used petroleum hydrocarbons as part of the service it intends to provide, and that it has a well documented system addressing how environmental issues are managed.     

绿色再制造工程及其在装备防腐蚀方面的应用

绿色再制造是废旧装备高技术修复、改造的产业化,是通过使用优于原始制造的先进技术,充分挖掘因腐蚀、磨损而失效的装备中蕴含的高附加值,具有显著的节能、节材、环保的特点.通过再制造关键技术对装备进行腐蚀控制,可提高装备防腐蚀的性能,赋予装备新的寿命,最大限度地保障装备的循环利用.为此,着重介绍了高速电弧喷涂长效防腐蚀技术、纳米电刷镀防腐蚀耐磨涂层技术、非晶态合金化学镀层防腐蚀技术、纳米固体薄膜减摩防腐蚀技术和纳米防腐蚀涂料及涂装等再制造防腐蚀技术及应用.