H0Cr17Ni6Mn3钢丝电塑性拉拔的研究

研究了脉冲电流对Ｈ０Ｃｒ１７Ｎｉ６Ｍｎ３钢丝室温拉拔过程的影响,结果表明,施加脉冲电流可使钢丝的拉拔力显著下降最大降低幅值达４０％,实验结果还表明,施加脉冲电流大大提高了钢丝的塑性变形能力,显著减缓了钢丝的加工硬化速度,使该钢丝在脉冲电流的作用下可从真径２．０ｍｍ拉拔至直径０．２５５ｍｍ而无需退火,拉拔钢线的力学性能实验结果表明,电塑性拉拔后的钢丝的抗拉强度下降。     

冷拔60Si2MnA钢丝的高强脉冲电流处理

由于加工硬化效应的影响,金属材料在发生塑性变形后其强度会增加.因此,冷拔钢丝的强度远高于拉拔前钢丝的强度,同时塑性变形能力远低于拉拔变形前.已发生较大拉拔变形的钢丝若需要进一步拉拔,常常需要采用高温退火方法来降低冷拔钢丝的强度和增加其塑性变形能力.本文将报道一种新的、可用于原位处理冷拔钢丝的高强脉冲电流处理方法.结果表明,在脉冲电流处理可使一种冷拔弹簧钢丝的强度显著降低,且塑性变形能力大幅增加.采用200 Hz的脉冲电流处理该冷拔弹簧钢丝1 min后,其力学性能与该钢丝在700℃条件下退火1 h后的力学性能相似.研究结果表明,高强脉冲电流处理方法是一种能使已发生加工硬化的金属材料有效软化的新方法.     

热处理工艺对超细不锈钢微丝制备性能的影响

制备了Ф0．035mm和Ф0．018mm两种规格的不锈钢微丝,分别在不同温度和以不同拉拔速度进行了退火,测定了微丝的力学性能。再将Ф0．035mm的微丝拉拔到Ф0．018inm,测定经不同工艺退火处理的微丝拉拔时的模耗和平均盘重,并与未经退火处理的微丝作比较。结果表明,随着退火温度的升高,相同直径微丝的抗拉强度下降,断后伸长率升高,尤其是单头平均盘重和平均模耗均大幅度下降。     

脉冲电流对Ti-6Al-4V冷拉拔变形行为的影响(英文)

利用电子背散射衍射(EBSD)及透射电镜(TEM)研究在脉冲电流作用下Ti-6Al-4V钛合金冷拉拔变形后组织及织构的演变。研究结果表明:施加脉冲电流可以促进非有利滑移取向的晶粒发生变形,从而使Ti-6Al-4V钛合金各晶粒之间的变形更为协调。常规拉拔和电塑性拉拔的丝材织构对比显示,脉冲电流促进钛合金柱面,a滑移,抑制锥面c+a滑移,通过晶界滑移协调c方向应变。电塑性拉拔钛合金的小角度晶界比例降低,说明脉冲电流抑制了变形诱发伴生位错晶界和几何必须晶界的形成。     

AZ31镁合金小直径薄壁管拉拔工艺及性能研究

实验研究了多道次拉拔过程中拉拔速度、拉拔变形量对AZ31镁合金小直径薄壁管材组织和性能的影响。研究结果表明,温度为300℃、拉拔速度为0.30 mm·s-1时,管材壁厚减薄均匀,可以保证镁合金管材的拉拔顺利进行。多道次拉拔可以成功制备Φ4 mm×0.2 mm的AZ31镁合金小直径薄壁管材。且随着累计变形程度的增加,镁合金的晶粒显著细化,当累积变形量达到95.4%时,平均晶粒尺寸从开始的22μm减小到8μm左右。最终小直径薄壁镁合金管材的抗拉强度达到了247.3 MPa,相应的伸长率为16.8%。     

工具形状对管材冷挤压加工变形特性的影响

近年来,以减轻重量的轴类部件向中空化方向发展。这些中空部件在管轴方向直径变动形状较多,其成型采用挤压加工,但因管材外径比模子成型部位内径小而出现减径现象。为此日本住友金属工业公司研究了挤压时挤压模形状对管材变形特性的影响,为适应管材和棒材冷拉拔。应根据各自条件选择模子形状。例如,拔制棒材时多使用拉拔阻力小的锥角为140的锥形模;拉拔管材时为使拉拔后管材外形美观而广泛使用R模子,R尺寸一般是管材直径的1．0-0．8倍。本研究试验材采用直径38．1mm、壁厚5．7mm、长度300mm的管材：锥形模的模子角度分别为5°,150°,250°内径31．9mm．支承座长度10．5mm;R形模子的半径曲率分别为25．65．130,300mm,内径31．9mm,支承座长度10．5mm。     

脉冲电流处理对新型热作模具钢热疲劳裂纹扩展的影响

采用自约束热疲劳试验法,研究了新型热作模具钢在热疲劳裂纹萌生阶段施加脉冲电流处理后的热疲劳裂纹扩展情况。结果表明:在热疲劳裂纹萌生的不同时机施加脉冲电流,对热疲劳裂纹扩展的影响效果存在明显差别。其中在热疲劳初始循环300次后再施加脉冲电流,效果较为显著,此时热疲劳裂纹细小,且均匀,裂纹扩展的速度较慢,横截面的显微硬度梯度下降也较慢。     

硬线盘条组织中局部晶粒粗大原因分析

硬线盘条是我公司的主要产品,钢号为45～70钢,规格有Ф6．5mm、Ф8.0mm等,主要供给钢丝厂用于拉拔成型各种规格的钢丝。但有部分产品在钢丝厂拉拔成型过程中发生了断裂观象,这既影响了用户的生产又给公司造成经济损失。笔者检验了断裂钢丝,发现原材料中局部晶粒粗大是钢丝拉拔断裂的主要原因。本文对硬线盘条产生局部晶粒粗大的原因进行了分析,并提出了改进措施,避免了拉拔断裂。     

0.92%C超细钢丝组织控制及断裂分析

研究了不同等温铅浴淬火后0.92%C钢丝的组织与性能,并对钢丝断裂机理进行了分析。结果表明,提高奥氏体化温度至980 ℃、降低铅浴温度至585 ℃,直径φ 0.84 mm钢丝中珠光体含量高,片层间距细小、均匀,抗拉强度、断面收缩率及硬度均达到最大,且钢丝拥有较强的连续拉拔性能,湿拉过程中的断丝率仅为0.004次/km。     

拉拔过程中珠光体钢丝帘线的织构分析与模拟

应用精确的线材织构测量方法，对珠光体钢丝帘线的织构进行了测量，实验结果表明，拉拔角、钢丝帘线与拉拔模具间的摩擦力是影响织构形成的主要因素。大的拉拔角，会导致在表层或亚表层形成{110}＜110＞环状织构，从而降低其拉拔及扭转能力。应用Taylor模型可以很好的对这一现象进行解释。     

EFFECTS OF HIGH-DENSITY CURRENT PULSES ON WORKHARDENING BEHAVIORS OF AUSTENITE STAINLESS STEELIN WIRE-DRAWING DEFORMATION

. IntroductionThe influence of highdensity pulsing current on the plastic deformation of metals hasattracted much attention in the wo.ld[1--14]. Scientists have studied the effects in Zn, Cd,Cu, Fe, W and stainless steel. It has been fOund that when concurrellt application of pulsingcurrent in plastic deformation the fiow stress of metal materials can be reduced[2I1o--14],the fatigue life can be increased[3], the amount of inner cracks can be reducedl8]. Now thephenomena of the flow stress …     

Electrical Pulse Shape Setting of Thin Ni49Ti51 Wires for Shape Memory Actuators

The effect of non-conventional electrical pulse treatment on microstructure and shape memory response of Ni₄₉Ti₅₁ wires was studied. High-power rapid current square pulses were applied to cold-drawn wires of 25 µm diameter. The TEM microstructures showed equiaxial recrystallization, with average grain size in the 100 nm range, after a double current pulse lasting 10 ms. Rapid current pulse treatment in Ti-rich NiTi induces shape memory effect with reduced thermal hysteresis and high recovery strain values. This novel treatment might replace conventional pre-device shape setting/training of the wire with a post-device shape setting with promising industrial advantages.     

Effect of roller die drawing on structure, texture and other properties of high carbon steel wires

In the work the effect of application of roller dies in process of drawing of high carbon steel wires for their structure, texture, residual stresses, surface roughness and mechanical properties has been investigated. Among structural features alignment of cementite lamellae to the wire axis by means of SEM and Pericolor 1500 has been quantitatively determined. Degree of cementite lamellae fracture in colonies parallel to wire axis has been estimated by Langford method. Obtained results were compared with those structural features for conventionally and hydrodynamically drawn wires. It has been found that degree of alignment of cementite lamellae in wires drawn in roller dies was smaller than in wires drawn conventionally and hydrodynamically but in the case of fracture degree the opposite result was noticed. Residual stresses were determined by electrochemical reversal pickling in water solution of sulphuric acid. A significant drop of longitudinal residual stresses in surface layer of wires drawn in roller die has been observed as compared to those stresses for conventionally and hydrodynamically drawn wires. Surface roughness of wires was measured with FORM TALYSURF profilographometer. It has been proved thad roller die drawing has formed very smooth surface with much smaller longitudinal and circumferential roghness parameters that for surface of wires drawn conventionally and hydrodynamically. In the work the tensile, yield and fatigue strength of tested wires were determined. It has been concluded that roller die drawing has many advantages as compared to conventional process and should be implemented in wire industry for larger scale.     

Influence of process variables on weld bead quality in two wire tandem submerged arc welding of HSLA steel

Two-wire tandem submerged arc welding process involves simultaneous depositions from two electrode wires with the leading wire usually connected to a DC power source and the trailing wire connected to a pulsed AC power source. The weld bead profile and mechanical properties in the tandem submerged welding are significantly affected by the leading and trailing wire current transients and the welding speed. We present here a detailed experimental study on the influence of leading wire current, trailing wire current pulses, and welding speed on the weld bead dimensions and mechanical properties in single-pass tandem submerged welding of a typical HSLA steel. It is realized that the weld bead penetration is primarily influenced by the leading wire current while the weld bead width and the reinforcement height are sensitive to the trailing wire current pulses. Greater magnitude of trailing wire current pulses and shorter negative pulse duration increase the weld pool volume leading to reduced cooling rate and poor mechanical properties as the formation of the strengthening phases like acicular ferrite is inhibited. In contrast, increase in welding speed reduces the rate of heat input thereby enhancing the cooling rate and the weld bead mechanical properties. A set of empirical relations are developed to estimate the weld bead dimensions and mechanical properties as function of the welding conditions. The predictions from the empirical relations and the corresponding measured results are observed to be in fair agreement.     

超大孔径聚晶金刚石拉丝模具单向走丝电火花线切割加工工艺研究

基于试验研究,创新性地提出了采用单向走丝电火花线切割机床对超大孔径聚晶金刚石拉丝模具的孔形进行粗加工。以金刚石粒度为25μm的直径22 mm、厚度20 mm的超大孔径聚晶金刚石拉丝模具为例,进行单向走丝电火花线切割加工定径区、压缩区和安全角的工艺研究,得出了加工工艺曲线,确定了最优加工工艺参数,提高了粗加工效率,确保了良好的孔形精度。结果表明:选择脉冲宽度4μs、脉冲间隔40μs、峰值电流15 A、走丝速度10 m/min时,可获得较满意的加工效果。     

Operating parameters for the continuous unidirectional solidification of the Al-1wt.% Si alloy drawn to fine wire

The Ohno process was applied to produce Al-lwt.% Si alloy rods for semiconductor devices. The casting conditions which enable production of an 8mm diameter rod having a mirror surface with a highly longitudinally oriented microstmcture was established. It was demonstrated that the alloy could be drawn, without the need of intermediate recrystallization or stress relief, to produce wires of 0.14 to 0.10mm in diameter. The rela-tionships between the casting conditions and wire breakage during fine wire drawing were also studied.     

As-deformed filament's density and transport currents of MgB2/Ti/Glidcop wire

Filamentary MgB₂/Ti/Glidcop wire has been manufactured by in situ process using hydrostatic extrusion, cold drawing and finally subjected to high pressure and standard densifications. Filament density of as-deformed wires was evaluated by micro-hardness measurements and related to applied deformation. It was found that filament's density and uniformity in as-deformed wire have a strong effect on the critical current density (J_c) of annealed samples. The highest J_c was measured for the filaments densified by cold isostatic pressing with 2 GPa and also for rotary swaged ones showing the best uniformity. Presented results showed the importance of filament density and homogeneity and also demonstrate suitability of hydrostatic extrusion for uniform long-length filamentary MgB₂ wires production.     

高温长时退火后纯铜丝的组织与性能

将ø8 mm退火态T2纯铜棒材,通过工业拉丝机进行多道次冷拉拔变形,最终得到ø3.5 mm的拉拔态试样,对其进行了600 ℃保温不同时间的退火试验,并通过组织形貌的观察、力学和电学性能的测试,研究了退火后纯铜试样组织与性能的关系。结果表明:拉拔态纯铜组织经退火后形成新的再结晶晶粒,并伴有退火孪晶比例的增加。随着退火时间的增长,再结晶晶粒不断长大,抗拉强度和断后伸长率小幅波动。退火态试样的平均抗拉强度为拉拔态的67.3%,平均断后伸长率是拉拔态试样的8倍,平均导电率比拉拔态提高约3.3%,且随着退火时间的增加导电性得到逐步提高。     

双丝脉冲MAG焊的熔滴过渡及工艺特征

搭建了并列式双丝脉冲MAG焊工艺试验系统,通过双丝脉冲协调控制器连接试验所用的两台电焊机,在试验过程中采集了焊接电流、电弧电压信号,并用高速摄像机对焊接过程的电弧行为与熔滴过渡过程进行了同步拍摄．应用上述试验系统,在实现稳定焊接过程的基础上,分别研究了脉冲峰值电压与脉冲基值电压、两个焊丝在垂直于焊道方向上的距离、焊枪倾角这三个因素对电弧行为、熔滴过渡过程及焊缝表面成形与焊缝几何尺寸的影响．确定了最理想的脉冲峰值一基值电压,并且发现在文中所述试验参数下,焊丝间距11mm为两电弧形成共熔池、同焊道的上临界距离．结果表明,随着焊枪倾角的增加,焊缝熔深增加,熔宽减小,在焊接速度和送丝速度不变的前提下余高增加．