带芯棒拔制钢管直径变化的研究

通过芯棒位置、拔制变形量等试验,研究了冷拔管外径扩大量和内径缩小量的变化规律,为准确控制冷拔管直径偏差奠定了基础。     

Deformation-induced martensitic transformation behavior in cold-rolled and cold-drawn type 316 stainless steels

We investigate deformation-induced martensitic transformation behavior in cold-rolled and cold-drawn specimens of type 316 stainless steel. Deformation-induced martensite preferentially nucleates at the twin boundary between the austenite matrix and a deformation twin. In the cold-rolled specimen, martensite formed at the twin boundary has a Kurdjumov–Sachs (K–S) relationship with both the austenite matrix and the deformation twin (“double K–S relationship”). In the cold-drawn specimen, two kinds of deformation twins with different twin planes are typically formed, and therefore deformation-induced martensites are formed where the deformation twin boundaries intersect: martensite thus has an imperfect “triple K–S relationship” with the austenite matrix and the two deformation twins. The complicated crystallographic orientation relationship between austenite and martensite grains strongly restricts the formation of some variants of deformation-induced martensites. Because of the difference in number of nucleation sites in the cold-drawn and cold-rolled specimens, martensitic transformation is more enhanced in the former than in the latter.     

用Φ76mm自动轧管机组试产小直径冷拔管料的研究

介绍了在Φ７６ｍｍ自动轧管机组上试产小直径热轧荒管的有关工艺及参数，生产中需采取的技术措施。比较了用小直径热轧荒管生产小直径薄壁冷拔钢管的冷拔道次数、成材率、金属消耗等。实践表明，用Φ７６ｍｍ自动轧管机组为冷拔提供小直径热轧荒管，扩大了机组的产品规格范围，使冷拔小直径薄壁钢管的生产工艺趋于合理。     

Interfacial Microstructure and Its Influence on Resistivity of Thin Layers Copper Cladding Steel Wires

The interfacial microstructure and resistivity of cold-drawn and annealed thin layers copper cladding steel (CCS) wires have been systematically investigated by the methods of scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), and resistivity testing. The results showed that the Cu and Fe atoms near interface diffused into each other matrixes. The Fe atoms diffused into Cu matrixes and formed a solid solution. The mechanism of solid solution is of substitution type. When the quantity of Fe atoms exceeds the maximum solubility, the supersaturated solid solution would form Fe clusters and decompose into base Cu and α-Fe precipitated phases under certain conditions. A few of α-Fe precipitates was observed in the copper near Cu/Fe interfaces of cold-drawn CCS wires, with 1–5 nm in size. A number of α-Fe precipitates of 1–20 nm in size can be detected in copper near Cu/Fe interfaces of CCS wires annealed at 850°C. When annealing temperature was less than 750°C, the resistivity of CCS wires annealed was lower than that of cold-drawn CCS wires. However, when annealing temperature was above 750°C, the resistivity of CCS wires was greater than that of cold-drawn CCS wires and increased with rising the annealing temperature. The relationship between nanoscale α-Fe precipitation and resistivity of CCS wires has been well discussed.     

管坯长度与冷拔管生产成本分析

建立了冷拔钢管管坯下料长度的数学模型，用CACPP软件系统研究了管坯长度对钢管生产成本的影响。     

汽车用冷拔精密无缝钢管的生产

乌克兰国立管材科研所在研究了汽车用冷拔精密无缝钢管的使用要求和原苏联有关冷拔精密无缝钢管的技术标准的基础上,制定了冷拔精密无缝钢管的生产工艺,并介绍了该工艺的特点及保证几何尺寸精度的一些措施。已按此工艺生产出满足使用要求的冷拔精密无缝钢管。     

Torsional Fatigue Cracking and Fracture Behaviors of Cold-Drawn Copper:Effects of Microstructure and Axial Stress

The fatigue cracking and fracture behavior of cold-drawn copper subjected to cyclic torsional loading were investigated in this study.It was found that with increasing stress amplitude,the fracture mode of cold-drawn copper gradually changes from a shear fracture on transverse maximum shear stress plane to a mixed shear mode on both transverse and longitudinal shear planes and finally turns to the shear fracture on multiple longitudinal shear planes.Combining the cracking morphology and the relationship between torsional fatigue cracking and the grain boundaries,the fracture mechanism of cold-drawn copper under cyclic torsional loading was analyzed and proposed by considering the effects of the microstructure and axial stress caused by torsion.Because of the promotion of the grain boundary distribution on longitudinal crack propagation and the inhibition of axial stress on transverse crack grown,the tendency of crack propagation along the longitudinal direction increases with increasing stress levels.     

Recrystallization of cold-drawn stainless steel

Summary Lengthening the holding time during the heating of cold-drawn 1Kh18N9T steel tubes reduces the initial and final recrystallization temperatures.An intensive lowering of the recrystallization temperature range occurs within the initial 10 min.The recrystallization process develops during the treatment of cold-drawn tubes at 975 to 1050°C as a result of heating without holding, and at 750 to 850°C by heating and a 3 hr holding period.     

对冷拔钢管生产计划管理的思考

冷拔钢管是钢材生产经营中难度较大的一个品种。介绍了在市场经济条件下冷拔钢管生产计划管理的五个原则：最大效益原则、比例固定原则、趋势预测原则、急难特小规格优先原则、生产均衡原则。可供同类企业生产计划管理参考。     

单向压缩实验测试大变形冷拉铝棒力学性能

描述了在室温下用单向压缩实验测试大变形条件下冷拉铝棒的力学性能的方法和步骤,求出了大变形条件下的材料常数。实验结果表明:端面不同摩擦条件对试样压缩后的高度应变,开始时影响较大,随着变形程度的增加影响减小;冷拉铝棒在大变形条件下的实际应力-应变曲线,可以较为准确地用指数形式的硬化曲线表示;加载历史对指数硬化规律有较大的影响;端面不同摩擦条件对试件压缩后的鼓出程度影响很大,垫聚乙烯对降低摩擦影响有明显效果;随着变形程度的增加,鼓出程度明显增加,但当变形程度达到一定的值以后,鼓出程度减小。     

高强度不锈钢绞索在桥梁工程中的应用

    检测了冷拉高强Cr-Ni-Mo不锈钢绞索的力学和物理性能;并从实验室研究和项目跟踪观察两方面介绍高强度不锈钢绞索的抗腐蚀性能;最后,展望了高强度不锈钢绞索在桥梁工程方面的应用.     

冷拔内直筋管拔制力的计算

采用工程法推导了冷拔内直筋管拔制力的计算公式。实验结果证明,理论计算值与实测值较吻合,因而,该公式可在冷拔内直筋管的生产中应用。     

辊拔内直筋钢管拔制力解析

利用主应力法解析了辊拔内直筋管的拔制力,并得到其解析解。该解比冷拔内直筋管的主应力解和冷拔实测值低许多。可为辊拔内直筋管设备选择提供依据。     

高精度冷拔钢管模具的磨削工艺研究

介绍了用于冷拔高精密钢管的高光洁度模具的加工工艺试验情况。试验结果表明,改进磨创工艺,采用普通磨床可以生产高光洁度模具,这种模具可显著提高冷拔管的光洁度,降低模耗。     

模具类型对冷拔管压扁性能的影响

分析了钢管冷拔时的受力状态,对比了锥形模与弧形模两种冷拔模具拔制时金属变形的不同,指出了冷拔管表面产生纵向裂纹的原因及对成品管压扁性能的影响。     

Magnetic and magnetotransport properties in thin Fe-rich wires processed by cold drawing

A study of microstructure (X-ray diffraction), magnetic properties (switching field associated with the magnetic bistability), and giant magnetoimpedance (GMI) effect in cold-drawn Fe_77.5B₁₅Si_7.5 amorphous wire is presented. The initial amorphous wire (obtained by the in-rotating-water spinning technique) with a diameter of 125 μm was subjected to cold drawing to decrease the diameter to 50 μm. Such cold-drawn wire was subjected to current annealing for tailoring the magnetic and GMI properties.     

缸筒用高精度冷拔管内表面质量分析

通过对热轧管、冷拔管内表面缺陷的测量、分析,指出了影响缸筒用高精度冷拔管内表面质量的主要缺陷是麻点,以及减少麻点的具体措施和方法。     

Experimental studies of plastic deformation behaviors in microheading process

The demand on microparts is increasing significantly due to the global trend of product miniaturization. Microforming provides a promising approach to fabricating microparts with good mechanical properties at low cost and high productivity. However, when the part dimension is scaled down to micro-level, the size effect occurs such that the deformation behaviors are different from those in macroscale. The investigations on size effect and the physics behind the phenomena observed are thus needed. In this research, the size effect on material deformation behavior is investigated based on the two heading cases, viz., central heading and end heading of the rods of the cold-drawn and annealed pure copper. It is found that the grain flow of the cold-drawn material is different from that of the annealed material and the coarse-grained material undergoes nonuniform deformation when the part size is in microscale. These phenomena can be explained by the strong texture in the cold-drawn material and the strain incompatibility among different grains in the coarse-grained material. In addition, the tooling surface texture generated in grinding process makes the friction different in different flow directions, resulting in the variation of formed profiles in both macro- and microparts. The surface roughening effect on the formed part becomes significant in microheading process. It has a close relationship with the grain size and crystallographic texture of the forming material. Furthermore, the punch–die and workpiece–tooling interfaces have a certain effect on deformation pressure. This leads to the scattering effect and the difference of the deformation pressure–stroke curves between the macroheading and microheading. The reported experimental results and the articulated findings provide a basis for understanding of material size effect in microheading process.     

Three Distinct Deformation Behaviors of Cementite Lamellae in a Cold-Drawn Pearlitic Wire

High-resolution transmission electron microscopy is used to investigate the deformation behaviors of cementite lamellae in the heavily cold-drawn piano wires. Three distinct morphologies of cementite are observed, namely, complete lamella, partly-broken lamella and nearly-disappeared lamella. For the complete cementite lamella, it remains a single-crystalline structure. For the partly-broken cementite lamella, polycrystalline structure and neck-down region appear to release the residual strain. The lattice expansion of ferrite takes place in two perpendicular directions indicating that the carbon atoms dissolve from cementite into ferrite lattices. An orientation relationship is found between ferrite and cementite phases in the cold-drawn pearlitic wire.     

冷拔管坯打头砧模的改进

简要分析了冷拔管坯打头时产生肩胛缺陷的原因，介绍了新结构的砧模。经实践验证，新结构的砧模可避免产生肩胛缺陷。