GH169合金筒形件变薄旋压试验

本文论述了ＧＨ１６９高温合金变薄旋压的试验过程，对合金的旋压性能，最佳变薄率，以及薄率，以及模拟ＦＴ８燃气轮机匣旋压成形，选择较为合理的工艺参数进行了分析。结果认为，ＧＨ１６９合金在固溶状态下，可旋转性较好，累计变薄率为６０％未见裂纹出现；当道次变薄率为３０％，两道次总变薄率约为５０％时，成形大直径薄壁带安装边机匣壳体是可行的。该结果为机匣壳体采用变薄旋压成形奠定了基础，对节省合金材料，提高产品几     

高温合金GH4169管材挤压工艺及组织分析

对高温合金GH4169管材挤压成形进行了工艺研究，确定了GHll40管材挤压成形工艺参数，分析了GH4169管材挤压力能参数变化规律，分析了管材挤压对组织性能的影响。研究结果发现，GH4169管材挤压成形时必须严格控制坯料温度、模具预热温度、润滑方式、挤压速度、挤压比等工艺参数。     

TC4合金流动旋压三维弹塑性有限元模拟

应用有限元软件MSC.Marc,建立了TC4合金筒形件流动旋压的三维弹塑性变形力学模型.研究了三轮同步热反旋过程中的三维变形图,管坯表面应力、应变以及旋压力分布规律.这对于优化TC4管材旋压工艺和缺陷的科学预报有重要的指导意义.     

镍基合金管材的强力旋压工艺

介绍了采用强力旋压工艺试制镍基合金管材的工艺流程,分析讨论了旋压工艺的工艺参数和工艺特点以及各种加工缺陷。     

管材挤压工艺分析及实验研究

对管材挤压成形进行了工艺分析及实验研究。确定了镁合金、7075铝合金、高温合金等几种材料管材挤压成形工艺参数，分析了管材挤压成形时变形力的变化规律。研究结果表明，管材挤压成形时必须严格控制坯料温度、模具预热温度、润滑方式、挤压速度、挤压比等工艺技术参数。以上工艺参数对挤压力均有不同程度的影响。     

GH3600合金管材热处理工艺研究

对比了3种不同成品的真空热处理制度,分析了热处理参数对成品室温、高温力学性能及晶粒度的影响,并寻找出GH3600合金成品管材最佳的热处理工艺。通过实验得出,GH3600合金管材在真空退火炉中经900℃×30 min处理,可获得良好的室温、高温力学性能和晶粒度水平。     

航天用GH3600合金管成形工艺研究

航天用GH3600合金管材的力学性能和晶粒度级别要求都很高。为了获得合格的管材,对其挤压工艺参数、冷轧过程中加工率范围、退火工艺参数进行了研究。结果表明,采用挤压开坯可明显细化组织,提高组织均匀性;成品冷加工率控制在51%~57%的范围内,不但可以获得良好的成品组织,同时提高了室温伸长率和高温下屈服强度。最终,合金管材达到了要求的技术指标。     

TB2钛合金筒形件旋压变形组织性能的研究

对TB2钛合金筒形件(管材)进行了变薄旋压成形试验,探讨了合金锻坯和挤压坯旋压变形后的组织性能、强化效应和塑性变形规律.结果表明,合金锻造变形率大于70%时可基本消除铸态组织;温度≥700℃、道次减薄率为20%～30%、进给比为0.5～1.0 mm·r-1时,合金筒形件旋压变形稳定.同时,对TB2钛合金旋压件进行了热处理试验,研究了固溶温度、时效温度对合金组织性能的影响,确定了合金的固溶温度和时效温度分别为710和520 ℃.     

高压开关屏蔽罩普旋成形工艺的研究

通过对毛坯尺寸确定、模板设计、旋压参数选择、旋压机床等等几方面对屏蔽罩零件的普旋成形工艺进行讨论；结合旋压成形试验过程，制定出较理想的工艺方案，试验验证该工艺完全适应屏蔽罩零件的成形加工，可作为旋压类似产品成形加工的参考。     

薄壁大尺寸铌铪合金零件强力旋压的数值模拟研究北大核心CSCD

探究了工艺参数对薄壁大尺寸铌铪合金零件强力旋压工艺的影响规律,以指导实际的生产过程。在实际工艺的基础上,利用Abaqus/Explicit软件建立其强力旋压的有限元模型,并通过正交试验极差分析法对旋轮与芯模间隙、旋轮进给比以及旋轮与旋压件之间的摩擦因数等工艺参数对旋压件贴模性的影响规律进行研究。结果表明,强力旋压过程中旋轮进给比对旋压件贴模性的影响程度最大,而旋轮与芯模间隙的影响程度最小。对于薄壁大尺寸铌铪合金零件,当旋轮进给比为0.24 mm·r^(-1)、旋轮与旋压件间的摩擦因数为0.05、旋轮与芯模间隙为3 mm时,强力旋压的贴模性最好,平均贴模间隙均值仅为1.003 mm。采用得到的工艺参数进行试验,进一步验证了有限元仿真分析的准确性。     

High temperature deformation mechanism and evolution of dislocation structure during creep of Ni-Base superalloy 713LC

Creep deformation of cast nickel base superalloy 713LC has been investigated in a temperature range of 723 to 982°C. The values of the stress exponent and activation energy for creep of the alloy vary with a combination of temperature and stress. Introduction of threshold stress for creep of the alloy provided an explanation of the high values of the stress exponent and the apparent activation energy. Microstructural evolution of the alloy with creep deformation has also been studied. The analysis of the creep mechanism has been supplemented by microstructural observations after deformation under various test conditions. The dislocation structure of the alloy at high temperature and low stress was different from that at low temperature and high stress. Shearing of γ′ particles by dislocation pairs was the dominant creep mechanism at low temperature and high stress whereas dislocation climb over γ′ particles was the rate controlling process of creep at high temperature and low stress.     

容器碟形封头球冠部分变形时的三维有限元数值模拟

本文应用ANSYS软件对碟形封头球冠部分冷旋压变形情况进行了有限元分析。在模拟条件的确定与实际主要工艺参数相一致的条件下 ,得出了封头球冠变形时应力、应变的分布规律。并计算了旋压力 ,其数值与实验测量结果相一致 ,证明了模拟结果的可靠性 ,为优化工艺参数提供了有效方法和可靠依据     

一种定向凝固镍基高温合金的高温低周疲劳行为

本文研究了一种定向凝固镍基高温合金的高温低周疲劳行为。结合对合金微观变形结构的观察,分析了温度、应变保持时间对合金低周疲劳性能的影响。结果表明,温度对合金的变形有着明显影响,在760℃以下合金呈现循环硬化,而在850℃和980℃时则表现为循环软化,这是由于合金在不同温度范围内具有不同的微观变形机制。在应变峰值、应变谷值以及同时在应变峰值和谷值分别引入保持时间后,合金的高温低周疲劳寿命均有一定程度的降低。     

大塑性变形材料晶界研究方法的新探索

为研究在大塑性变形过程中超细晶粒结构形成的机理 ,设计并熔铸了含微量Zr、B的Al合金Al 0 2 7wt%Zr 0 0 6 4wt%B合金 ,该合金中晶界上分布有大量的B2 Zr细小化合物颗粒 ,晶内则几乎没有B2 Zr分布。通过室温轧制及热锻后退火实验表明B2 Zr具有很高稳定性 ,而且再结晶后B2 Zr仍位于原变形后的位置 ,不随再结晶晶界的迁移而迁移 ,证明了该合金可用于大塑性变形过程中晶粒变形细化过程及再结晶和晶粒长大的研究     

单辊法制备非晶合金中冷却速率的数值计算

以非晶合金形成过程中的传热分析为基础，计算了超导热急冷设备和铜急冷设备两种设备下非晶合金快速凝固开始后的冷却速率，并计算分析了在铜辊外表面涂镍或不锈钢后对非晶合金冷却速率的影响。结果发现，超导热急冷设备对非晶合金的快速凝固效果比铜急冷设备要好，在铜辊外表面涂镍或不锈钢后非晶合金的冷却速率在凝固开始一段时间内明显降低，其中涂不锈钢后最为明显。     

影响A356铝合金车轮旋压成形品质的因素分析

从铸旋铝合金车轮的热旋压成形工艺出发,分析了A356材料强韧化原因,分析表明：热塑性变形可成为A356铝合金强韧化的新途径,以此为基础发展的铸旋成形工艺可满足汽车轮毂进一步轻量化的要求。分析了影响车轮旋压成形的温度、毛坯形状、模具结构等因素,对稳定旋压成形工艺具有实际指导意义。     

Deformation Characterization of Friction-Stir-Welded Tubes by Hydraulic Bulge Testing

In this article, the large-diameter thin-walled aluminum alloy tubes were produced using a hybrid process combining friction-stir welding (FSW) and spinning. For this novel process, rolled aluminum alloy sheets with a thickness about 2–3 times the wall thickness of target tube, were FSW to form cylinders, and then the cylinders were subjected to spinning to get thin-walled aluminum alloy tubes. Both experimental and simulation study were conducted to investigate the deformation characterization of the FSW tube during hydraulic bulge testing, and the stress and strain states and thickness distribution of the FSW tube were investigated. It was found that the common defects of FSW tube can be significantly improved by specific welding devices. The ductility of the tube is considerably improved with nearly two times higher bulge ratio than as-spun tube after annealing treatment at 300°C. But the annealed tube still shows a high nonuniform wall thickness distribution due to the inhomogeneous deformation characteristics. With increasing deformation of the tube, the gap between the hoop and axial stress for the weld and base metal (BM) decreases. However, the hoop and axial stress of the weld are always greater than those of the BM at the same pressure.     

Ausscheidungshärtbare Nickelbasis‐Superlegierungen für den Verschleißschutz im Hochtemperaturbereich

Precipitation‐hardenable nickel‐based super alloys for wear resistance in the high‐temperature range Precipitation‐hardenable nickel based filler metals are already available for the original manufacture as well as regeneration of high‐temperature‐resistant components. Their special strength properties at operating temperatures of about 800°C are based on their capability of being hardened by the so‐called γ′‐phase Ni₃(Ti, AI), which precipitates after a multistage heat treatment, among other factors. However, the weld‐surfaced components cannot be heat‐treated in this manner without impairing the mechanical qualities of the base metal. For this reason, a search has been conducted for a weld surfacing alloy which does not require multistage annealing, or which can be applied with a heat treatment which does not damage the substrate. The objective was the development of a precipitation‐hardenable test alloy for MIG weld surfacing with flux‐cored wire. For this purpose, the chemical composition of the alloy had to be selected for achieving high‐temperature properties similar to those of nickel‐based super alloys in the hardened condition without the need of post‐weld heat treatment which damages the substrate. The alloys were applied by multi‐pass weld surfacing and subjected to different heat treatments. The characteristic strength values were determined by hardness tests. Effects of the welding parameters as well as the resulting solidification shapes were characterised by metallographic analyses. Scanning electron micrographs of selected test alloys have confirmed the precipitation of the γ′‐phase and the formation of further hard phases. From the results, recommendations can be derived for weld surfacing of high‐temperature‐resistant claddings with respect to process control, alloy composition, and post‐weld heat treatment.     

7055铝合金高温塑性变形的热模拟研究

采用Gleeble-1500D热模拟机研究了7055铝合金在应变速率为0.01、0.1和1s-1、变形温度为300～450℃,最大真应变为0.7条件下的高温塑性变形行为,分析了合金流变应力与应变速率、变形温度之间的关系,计算了合金高温塑性变形时的变形激活能,并观察了合金变形过程中显微组织变化情况。结果表明:合金在热变形过程中流变应力随温度的升高而减小,随应变速率的增加而增大,7055铝合金的高温塑性变形行为可以用包含Zener-Hollomon参数的流变应力方程进行描述。该合金在实验条件范围内热变形以动态回复为主要软化机制并伴随极少量的再结晶发生。     

同/异种合金焊接接头旋压成形研究现状及展望

针对同/异种合金焊接接头的旋压成形是制造航空航天零件的重要加工方式,主要综述了近年来国内外同/异种合金焊接接头旋压成形的研究进展,总结了同种合金焊接接头的旋压成形的工艺过程和微观组织演化规律,探究了不同工艺参数条件对成形的影响.结果表明:对于同种合金,先焊接后旋压有助于降低焊接接头组织的不均匀性,在一定程度上提高焊接接...