优特钢线棒材减定径技术的进步与展望

线棒材减定径机组是优特钢线棒材产线的最关键机组，可实现对线棒材尺寸精度及表面质量的控制，从而满足高品质线棒材生产的要求。介绍了线棒材减定径工艺装备技术的最新应用进展及国内自主创新情况，包括集中传动式、双模块式及单独传动式线材减定径机组，三辊式、二辊式及四辊式棒材减定径机组。对于优特钢线棒材产线，绝大部分轧制工艺装备已实现了自主设计制造，线棒材减定径装备技术正在逐步取得应用，需加快推进关键装备技术的自主化。同时指出，随着用户对产线生产效率、产品质量及智能化需求的不断提高，高速度、高精度及智能化是线棒材减定径机组未来发展的主要趋势。     

叶片用小规格TC4棒材的组织和织构研究

采用径锻加工方式制备叶片用Φ30 mm的小规格TC4合金棒材，并使用金相显微镜、XRD衍射仪及电子背散射(EBSD)技术研究棒材边部到心部的显微组织、物相组成和微观织构，并分析组织和织构对棒材力学性能一致性以及超声探伤杂波水平的影响。结果表明，径锻棒材内部晶粒得到充分细化，从边部到心部晶粒尺寸逐渐增大，径锻棒材的β转变片层组织被破碎。棒材中含有少量等轴状β相晶粒，分布在α_p的晶界和β转变组织中。棒材边部为■板织构，R/2和心部为■轴向的丝织构，且棒材的织构强度从边部到心部逐渐减弱。棒材抗拉和屈服强度的变异系数仅为0.24%和0.29%，具有优异的一致性。径锻加工小规格TC4棒材的超声波杂波水平为Φ0.8～9 d B，相对于轧制棒材杂波升高，这与径锻棒材显微组织不均匀区域的晶体取向变化有关。     

热加工工艺对叶片用TC4钛合金棒材组织与性能的影响

为优化发动机叶片用TC4钛合金棒材热加工工艺，对比研究了相同条件下精锻和轧制工艺对棒材组织与性能的影响，以及精锻温度和精锻变形量对棒材组织与性能的影响。结果表明：与精锻相比，轧制变形时间短、温升明显，导致轧制棒材初生α相含量低，室温强度和高温强度明显低于精锻棒材，但组织更加均匀，超声探伤杂波水平低。此外，随着精锻温度的升高，棒材初生α相含量减少，室温强度和高温强度下降，但超声探伤杂波水平降低；随着精锻变形量的增大，棒材变形不均匀性加剧，室温强度和高温强度逐渐提高，但超声探伤杂波水平增大。精锻温度为940℃时，TC4钛合金棒材的组织与性能匹配较好。     

不锈钢棒材应变不均匀对两相微观结构演变的影响

双相不锈钢热轧制备过程中应力应变分配不均，导致奥氏体相和铁素体相软化、相变竞争激烈，组织结构演变和性能调控复杂。以热轧2209双相不锈钢棒材为研究对象，采用有限元仿真技术对Φ43 mm棒材6道次热连轧过程进行三维热力耦合模拟，结果表明，棒材横截面上特征区域的应变与温度变化分布极不均匀；中心金属温度最高且塑性应变最大。对棒材不同特征区域的微观分析表明，在棒材表面和内部，两相体积占比不均匀且晶粒动态再结晶不协调，棒材表面δ→γ相变占据主导；然而在棒材内部区域，在高温高应变速率工况下，发生γ→δ逆相变。因此通过控制轧制工艺改善不锈钢两相协调变形行为，从而全面提升棒材力学性能。     

可分槽驱动的冷床对齐辊道

针对棒材冷床对齐辊道存在易使棒材产生弯曲和表面受损的问题，设计了一种新型的可分槽驱动的冷床对齐辊道，实现了根据各倍尺棒材所需的对齐量进行分别精确对齐控制，使弯钢现象和棒材表面质量得到明显改善。     

棒材生产线定支包装控制技术的研究

分析了棒材生产定支控制工艺的机理，论述了棒材运行传输的工艺条件及运动规律，根据实际生产使用要求，在不改变现有的棒材传输、包装工艺方式的基础上，提出了基于微差速分离的棒材在线定支包装控制的解决方案，并应用于工业现场，取得了良好的使用效果。     

轧制和热处理工艺对TC4钛合金棒材超声声速的影响

为实现对TC4钛合金棒材超声声速的控制，对比研究了轧制和热处理（包括固溶处理、固溶时效处理和三重热处理）对TC4钛合金棒材超声声速的影响。结果表明：轧制温度和变形量对TC4钛合金棒材超声声速影响较大，随着轧制温度的降低和轧制变形量的增大，超声声速逐渐降低；热处理温度和冷却方式对棒材超声声速也有一定的影响，随着固溶温度的升高和时效温度的降低，超声声速逐渐升高；与固溶时效处理相比，经三重热处理后的棒材超声声速更高，且第一重热处理采用水冷的棒材最终超声声速高于采用空冷的棒材。     

核级锆材质量控制——基于故障树法的Zr-4棒材氢元素检测超标原因排查分析

在Zr-4棒材的失效形式中，氢致开裂是最隐蔽且又破坏最大的失效形式。其主要表现为锆与氢反应形成Zr Hx产物，该产物易分解，从而产生裂纹源，影响Zr-4棒材的质量，严重威胁核反应堆的安全。某公司在Zr-4段塞棒的材加工过程中，出现Zr-4棒材成品的氢元素检测超标现象。本文基于故障树的方法，通过实验室检测对比实验、Zr-4棒材的生产工艺排查、生产设备排查、人员技能排查及质量体系排查对比，研究了Zr-4棒材氢元素检测超标的原因。结果表明：Zr-4棒材热旋锻过程工序可能导致Zr-4棒材氢元素数值结果异常。通过原因排查，机理分析和工艺改进，确定了Zr-4棒材氢元素检测异常的质量改进方法，为我国核级锆材生产工艺控制过程的质量管理提供了一种新方法和新思路，为我国核反应堆的安全提供保证。     

铝合金高精度拉制棒材的工艺研究

通过对２００７合金、ＬＣ４合金高精度拉制棒材的试验研究，简述高精度棒材的生产工艺，以及拉伸模、冷拉伸率等对棒材尺寸精度的影响。     

干燥对挤压棒裂纹的影响

从湿度梯度、温度梯度和棒材长度等三个方面探讨了干燥对挤压棒产生裂纹的影响，研究结果表明，适当控制干燥时的温度梯度、湿度梯度和棒材长度可提高棒材的合格率。     

Some studies on hot extrusion of rapidly solidified Mg alloys

Rapidly solidified magnesium alloys show great potential for application in automotive and aerospace industries. In this study, Mg-Al-Zn alloys (AZ91) were rapidly solidified by a melt-spinning process to form ribbons. Pulverized ribbons were cold-compacted and then hot-extruded to form rods. During extrusion, a specially designed die with constant strain rate profile was used and found to be advantageous. By properly establishing the complete process, extruded rods of rapidly solidified AZ91 alloys exhibiting good combination of room temperature strength and ductility were produced. Microstructural investigations were carried out on melt-spun ribbons and extruded rods. Effects of extrusion die shape, extrusion ratio, and extrusion temperature on mechanical properties of the extruded rods were also investigated.     

2A50合金正反挤压棒粗晶的对比

阐述了２Ａ５０合金反挤压棒材粗晶区的分布特征,以及与正抗压棒材粗晶环的差异。通过对该事金正反挤压棒粗晶的试验研究,发现２Ａ５０合金反挤压棒材粗晶区由两部分组成;最外层深度小于２．０ｍｍ的粗大晶粒区和由粗晶区向中心延伸的小晶粒区,这同正坟棒材粗晶环有很大差异。试验结果表明：２Ａ５０合金反挤压棒材边部由粗晶区向中心延伸的小晶粒区是不完全再结晶组织,不应属于粗晶环。     

Experimental evaluation of clad metallic buffer rods for high temperature ultrasonic measurements

The fabrication, evaluation and several applications of metallic buffer rods consisting of a core and a cladding are presented. The clad rods can have a taper shape and the cladding is fabricated by thermal spray techniques. Clad rods as long as 1 m have been fabricated. Experimental results show that the ultrasonic signals detected at 5 MHz with these buffer rods have very high signal to noise ratio (>35 dB) for both longitudinal and shear waves in a reflection mode. Applications to the measurement of the thickness of hot plates and molten metals up to 960°C and to the on-line monitoring of polymer extrusion are reported.     

Fabrication of 93W–Ni–Fe alloy large-diameter rods by powder extrusion molding

A powder extrusion molding (PEM) process has been used for the manufacturing of tungsten heavy alloy rods with large length to diameter ratio. An improved wax-based multi-component binder was developed for PEM of 93W–Ni–Fe alloy. The miscibility of its components and the characteristics of the binder were evaluated and good thermal–physical properties were obtained. Also, the feedstock rheological properties, extrusion molding and debinding process were studied. The feedstock exhibited a pseudo-plastic flow behavior. The large length to diameter ratio rods, with diameters up to 36 mm were extruded at 65 °C by optimizing the extrusion process. A two-step debinding process was employed to remove the binder in the extruded rods. Solvent debinding was carried out in n-heptane at 45 °C to extract the soluble components. A process of repeated short time immersion and drying of the extruded rods (called short-period solvent debinding) was developed and using this novel technique the binder removed was raised from 45% to 60%. SEM analyses indicated that a large volume of pores was formed in debound rods, but had not created interpenetrating pore channels yet. The rest of the binder could be thermally extracted at a high heating rate without defects.     

Microstructre of Mg-6.4Zn-1.1Y Alloy Fabricatec by Rapid Solidification and Reciprocating Extrusion

In order to explore the methods to prepare high-strength quasicrystal-reinforced magnesium alloys, the flakes of rapidly solidified Mg-6.4Zn-1.1Y magnesium alloy with thickness of 50-60冚m were obtained by a melt spinning single-roller device, and then the flakes were processed into rods by reciprocating extrusion and direct extrusion. The microstructure of the alloy was analyzed by optical microscope and SEM, and the constituent phases were identified by XRD. Phase transformation and its onset temperature were determined by differential thermal analyzer (DTA). The analysis result shows that rapid solidification for Mg-6.4Zn-1.1Y alloy can inhibit the eutectic reactions, broaden the solid solubility of Zn in 冄-Mg solute solution, and impede the formation of Mg3Y2Zn3 and MgZn2 compounds, and thus help the icosahedral Mg3YZn6 quasicrystal formed directly from the melt. The microstructure of the flakes consists of the -Mg solid solution and icosahedral Mg3YZn6 quasicrystal. Dense rods can be made from the flakes by 2-pass reciprocating extrusion and direct extrusion. The interfaces between flakes in the rods can be welded and jointed perfectly. During the reciprocating extrusion and direct extrusion process, more Mg3YZn6 compounds are precipitated and distributed uniformly, whereas the rods possesses fine microstructures inherited from rapidly solidified flakes. The rods contain only two phases: 冄-magnesium solid solution as matrix and fine icosahedral Mg3YZn6 quasicrystal which disperses uniformly in the matrix.     

Production of long rods by sequential extrusion of wood powders

Wood-based materials are environment-friendly resources as they eventually decompose into carbon dioxide and water after disposal. However, there are a number of productivity and workability related problems: it takes many years for a tree to grow to a useable size, and wood materials are more difficult to process than metal and plastic materials. To overcome these problems, sequential extrusion of cryptomeria powders mixed with Japanese cypress was performed in an attempt to make long wooden rods. In sequential extrusion, the powder replenishment and short-stroke extrusion steps are alternated until the desired rods are obtained. In this process, a strong extrusion seams were required between the new powder batch and the extruded portion of the rod. A steel container with a device for controlling replenishment temperature was used to increase the bonding strength of extruded rods. The results showed that there exist an optimal replenishment pressure and temperature, and that, under these optimal conditions, long rods with the strength of natural wood can be obtained. Finally, it is found that the presence of back-pressure is key in producing sound, high-strength rods.     

增塑粉末挤压成形新技术

以硬质合金材质体系为对象，针对目前主要的一类挤压成形设备－真空螺杆挤压机，开发出了一种增塑粉末挤压成形新技术。从理论上系统分析了成形过程的物理本质及粘结剂非等温脱脂机理与动力学，并推导出了一系列流变学材料函数。理论分析与实验相结合，开发出了一种多组元新粘剂设计与制备技术，优化了挤压工艺参数，制备了直径20mm的硬质合金挤压棒。     

MICROSTRUCTURE OF Mg-6.4Zn-1.1Y ALLOY FABRICATED BY RAPID SOLIDIFICATION AND RECIPROCATING EXTRUSION

In order to explore the methods to prepare high-strength quasicrystal-reinforced magnesium alloys, the flakes of rapidly solidified Mg-6.4Zn-1.1 Y magnesium alloy with a thickness of 50-60 um were obtained by a melt spinning single-roller device, and the flakes were then processed into rods by reciprocating extrusion and direct extrusion. The microstructure of the alloy was analyzed by optical microscope and SEM, and the constituent phases were identified by XRD. Phase transformation and its onset temperature were determined by differential thermal analyzer (DTA). The analysis result shows that rapid solidification for Mg-6.4Zn-1.1Y alloy can inhibit the eutectic reactions, broaden the solid solubility of Zn in a-Mg solute solution, and impede the formation of Mg3 Y2 Zn3 and MgZn2 compounds, and thus help the icosahedral Mg3 YZn6 quasicrystal formed directly from the melt. The mierostrueture of the flakes consists of the a-Mg solid solution and icosahedral Mg3 YZn6 quasierystal. Dense rods can be made from the flakes by two-pass reciprocating extrusion and direct extrusion. The interfaces between flakes in the rods can be welded and jointed perfectly. During the reciprocating extrusion and direct extrusion process, more Mg3 YZn6 compounds are precipitated and distributed uniformly, whereas the rods possess fine microstructures inherited from rapidly solidified flakes. The rods contain only two phases: amagnesium solid solution as matrix and fine icosahedral Mg3 YZn6 quasicrystal which disperses uniformly in the matrix.     

Microstructure and properties of AZ80 magnesium alloy prepared by hot extrusion from recycled machined chips

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Influence of extrusion parameters on grain size and texture distributions of AZ31 alloy

Grain size and texture distributions have great influences on the mechanical properties of extruded rods. In order to study grain size and texture evolution during the hot extrusion process, direct extrusion tests were carried out with a variety of extrusion parameters (extrusion ratio, temperature and velocity) for commercial as-cast AZ31 magnesium alloys. Extruded specimens were investigated by optical microscopy (OM) and electron backscattered diffraction (EBSD). Experimental results show that extrusion ratio is the most important parameter for grain size refinement. Basal fiber textures with various (0 0 0 2) pole intensities are observed in extruded rods. Maximum intensities increase with the decreasing extrusion ratio and the increasing velocity, while the influence of temperature depends on the value of extrusion ratio and velocity.