变形高温合金纯净熔炼设备及工艺研究进展

本文试图对国内外近年来变形高温合金纯净设备及其熔炼技术的发展情况进行综述。文章总结了变形高温合金中夹杂物的分类方法,调研了国内外变形高温合金熔炼设备生产厂家,分析了真空感应熔炼炉、电渣炉、真空自耗炉的设备特点与技术,归纳了国内外变形高温合金真空感应熔炼、真空感应熔炼+保护气氛电渣重熔、真空感应熔炼+真空自耗重熔、真空感应熔炼+保护气氛电渣重熔+真空自耗重熔四类工艺的研究进展。最后提出了提升我国变形高温合金冶金质量与性能的一些建议。     

真空熔炼的近期进展

本文对特种熔炼，包括真空感应熔炼、冷坩埚熔炼、真空电弧重熔、真空电弧双电极重熔、电子束熔炼以及在真空或高压条件下电渣重熔的近期进展作了综述。并对特种熔炼的某些发展方向给予了一定的评论。     

高温合金的真空感应超纯净熔炼

论述了真空感应熔炼（VIM）超纯净高温合金工艺方法的特点及应用，讨论了高温合金真空感应熔炼的辅助工艺措施。     

电渣重熔连续定向凝固FGH96合金非金属夹杂物研究

本文通过真空感应熔炼+惰性气氛保护电渣重熔连续定向凝固制备FGH96合金,对FGH96合金中的非金属夹杂物进行对比研究。结果表明,活泼元素Al、Ti、Zr、Ce、B等有轻微的烧损,主要元素含量都在合金要求的范围之内,氧含量略有降低,达到了真空熔炼的水平,氮含量有较大幅度的降低,主要存在两种类型的夹杂物,呈球形的夹杂物是Al、Ti、Mg的复合氧化物和TiN。图像统计分析结果表明,和传统电渣重熔相比,电渣重熔连续定向凝固工艺重熔后FGH96合金中的非金属夹杂物面积百分比、100个视场中的夹杂物个数降低了50%以上,夹杂物的最大尺寸由16μm降低到5.5μm,这主要是与熔池的形状、深度和结晶方式有较大关系,传统电渣重熔过程中金属熔池的形状是V字形,深度约占铸锭直径的50%左右,而电渣重熔连续定向凝固过程中形成的熔池呈扁平状,深度占直径10-20%。     

硫化物形态对超高强度钢冲击韧性的影响

本文对比分析了"真空感应+真空自耗重熔"和"电弧炉+VOD+真空自耗重熔"两种工艺冶炼的超高强度G50钢力学性能.利用扫描电镜和能谱分析等检测手段研究了不同冶炼工艺生产的G50钢中夹杂物类型和尺寸分布.研究结果表明:电弧炉+VOD+真空自耗重熔工艺冶炼的G50钢横向和纵向冲击韧性分别相对"VIM+VAR"工艺得到很大的改善,各向均匀性得到改善.电弧炉+VOD+真空自耗重熔工艺冶炼的G50钢中夹杂物颗粒状和椭圆形弥散均匀分布,阻碍空洞合并,导致冲击性能尤其是横向冲击性能得到极大的改善.     

真空电渣重熔的冶金特性

真空电渣重熔具有脱氧性能好,防止金属氧化等许多优异的冶金特性.本文通过对真空电渣重熔与普通电渣重熔、气体保护熔炼和真空电弧熔炼等冶金特性的分析对比,找出真空电渣重熔的冶金特性,表明发展真空电渣重熔的意义.     

钒基贮氢合金的公斤级熔炼工艺与性能改善

研究了V-60%(TiCrFeMn)贮氢合金的公斤级熔炼工艺和热处理工艺,采用真空中频感应和非自耗真空电弧熔炼两种不同的熔炼方法制备公斤级钒基贮氢合金,采用高温退火方法改善合金的性能.结果表明,采用真空中频感应熔炼的合金由于熔炼过程中合金液与坩埚反应,致使合金含氧量过高,合金性能恶化,而采用非自耗真空电弧熔炼的合金表现...     

Ni基高温合金真空感应熔炼脱硫

研究了使用CaO坩埚真空感应熔炼炼Ni基高温合金过程中的脱硫情况;分析了加Al的脱硫作用;结合坩埚壁的XRD分析和成分分析数据讨论了CaO坩埚脱硫机理;对CaO坩埚内壁表面发生的化学反应进行了初步热力学计算和讨论.     

关于几种合金的铸造缺陷

在我所目前研制过的仪表合金中,除了少数的品种采用大气下感应熔炼、电渣重熔之外,大多数品种是采用真空熔炼,或再经过真空自耗重熔。合金的铸锭也多为真空下浇铸的和充氩气下浇铸的。在这些合金的研制中,铸造缺陷往往会造成很大的危害,威胁热加工和冷加工的继续进行。它会造成合金的不必要的浪费和成     

真空冶金现状及其应用前景

叙述了真空冶金的发展及目前所采用的各种真空冶金方法，讨论了真空冶金的特点及几种主要真空冶金方法的自身特点及应用，分析了真空冶金方法及设备的发展动态，讨论了新材料制备工艺方法的选择，对国内外高温合金及特种钢的熔炼数据进行了初步对比。     

Progress in the vacuum (VIM,VAR) melting of high performance alloys

During the past 30 years vacuum melting has made possible the commercial production of entirely new classes of advanced alloys. This paper examines the progress made in acuum induction melting (VIM) and vacuum arc remelting (VAR), and discusses the zmpact of these processes on the remarkable growth of the superalloy industry.     

Improvement in mechanical properties of C300 maraging steel by application of VAR process

The prime objective of this research was to improve the mechanical properties of C300 maraging steels originally cast in the vaccum induction melting (VIM) and AIM furnaces by application of vaccum arc remelting (VAR) process. For this purpose two sets of C300 maraging steel with different amounts of Ti were cast in two different types of furnaces. Three bars with 1, 1.5 and 2 wt% of Ti were produced in the argon induction melting (AIM) furnace and two bars with 0.65 and 1 wt% Ti in the VIM furnace. Then all of the bars were subjected to VAR process in order to study the effects of this process on the reduction of N and O gases and inclusions, hence improvement in the mechanical properties. The results show that the total reduction of N and O gases in the bars cast in the AIM furnace was up to 40%, the amounts of inclusions irrespective of their kind reduced up to 30% while ductility and impact energy increased up to 40%. However, these parameters in the bars cast in the VIM furnace changed as follows: total gas reduction decreased by 12%, ductility and impact energy increased by 30% and 47%, respectively. So this research provides a very informative data base for those who are interested in studying the effect of VAR process on the mechanical properties of this kind of cast steel.     

高温合金熔炼工艺讨论

分析了高温合金所采用的各种冶炼方法,调研了几种主要冶炼方法的设备情况,讨论了其应用及发展动态,对比了国内外高温合金的熔炼数据,讨论了国内外粉末高温合金熔炼方法的差别,研究了我国粉末高温合金VIM+VAR双联工艺对锻件性能的影响。研究结果表明,为提高我国粉末高温合金纯净度,在着力改进高温合金熔炼工艺的基础上,应积极发展并提高双联及三联熔炼等新工艺。     

探索新强韧化机制 开拓超高强度钢新领域

论述了超细化马氏体板条，共格沉淀新强化相（Laves相），M2C碳化物和残余—逆转变奥氏体向马氏体相变诱发塑性等强韧化机理，用超纯洁熔炼、超均匀化及控制相变等工艺，获得一种低碳-14Cr-12Co-5Mo-Me新型超高强度、高塑性、高韧性不锈钢。     

Multiscale modelling approach for predicting solidification structure evolution in vacuum arc remelted superalloy ingots

Abstract

The present paper describes the mathematical development and validation of a comprehensive stochastic model capable of predicting at the mesoscopic level the solidification structure, Laves, and NbC phases in superalloy ingots processed by vacuum arc remelting (VAR) technology. The multiscale modelling approach consists of a coupling between a fully transient deterministic macroscopic code and a stochastic mesoscopic solidification structure code. Predictions from the model were validated against experimental measurements. Multiscale model predictions are compared against a commercial size VAR ingot.     

镍基高温合金脱氮工艺的研究

研究了真空感应熔炼镍基高温合金过程中的脱氮工艺并初步分析了镍基高温合金中钛对氮的相互作用,近似地计算出其相互作用系数.在现有的条件下,本研究的目的是获得实验数据以此来分析氮的含量并计算出钛对氮的相互作用系数,从而确定最佳的脱氮工艺.     

A hybrid arc spray forming technique for the manufacture of nickel superalloy IN617

Spray forming produces cast microstructures with comparatively low macro‐ and micro‐structural chemical segregation and is thus well‐suited for the manufacture of complex chemistry, multi‐component alloys that otherwise show strong elemental segregation. Although spray formed Ni superalloys have shown properties equivalent or superior to their conventionally cast/wrought counterparts, they have not been adopted commercially because of the difficulties in ensuring a high process yield and the complexity and associated cost of large‐scale Ni superalloy melting. In this paper, we describe a hybrid arc spray forming (HASF) process in which costly, large‐scale alloy melting as pre‐cursor to spray forming is avoided by the use of a consumable wire feedstock. To achieve thermal conditions of melt spray forming – essential to produce a refined, polygonal grain structure – a customised secondary atomisation system has been developed. Fe‐0.8 wt%C and Ni superalloy IN617 microstructures and preliminary mechanical properties suggested that hybrid arc spray forming may offer an attractive combination of convenience, low cost and mechanical performance.     

镍基高温合金脱氧的研究

氧在高温合金中是作为有害杂质元素存在的,通常是疲劳裂纹的萌生地及扩展通道,从而影响高温合金的蠕变、持久强度等性能.本研究在现有条件下,确定了氧在镍基高温合金中存在主要形态为氧化铝夹杂,根据得到的实验数据分析和计算,初步研究了真空感应熔炼条件下碳和铝对镍基高温合金的脱氧机理, 实验中氧含量最低为0.0006%,达到了小于0.001%的目标值.     

A high performance wrought nickel-base superalloy El-929

El-929, a high performance Soviet nickel-base wrought superalloy having the composition, Ni-14Co-10Cr-5W-4Mo-4Al-2Ti-0.5V-0.1C-0.02B (wt %) was prepared by vacuum induction melting and vacuum arc refining. The ingots were homogenized and hammer forged. The microstructural inhomogeneities in the forged product were examined. Tensile and stress-rupture properties, and fracture behaviour were observed to vary between the central and the outer portion of the forged stock.     

铸锭GH 3625合金微观偏析及均匀化热处理

为消除铸态GH 3625合金的显微偏析,改善其热加工性能,建立其均匀化动力学并制订均匀化处理制度,采用ImagePro Plus软件、扫描电镜(SEM)和能谱分析仪(EDS),对通过真空感应熔炼和电渣重熔双联工艺制备的GH 3625合金电渣锭的显微组织及元素偏析情况进行分析和研究.同时,对铸态GH 3625合金在不同温度下同一时间及同一温度下不同时间进行了均匀化处理.结果表明:GH 3625合金电渣锭存在明显的枝晶间微观偏析,主要偏析元素为Nb、Mo等,形成富Nb的Laves相、MC碳化物;不同元素的偏析程度为NbMoTiAlCr;Nb、Mo、Ti、Al在枝晶间大量富集,使得Laves等多种非平衡相在枝晶间析出;在均匀化过程中,随着均匀化温度的升高和时间的延长,偏析元素逐渐扩散均匀;当热处理制度为1 130℃×32 h时,元素偏析基本消除;Laves相体积分数随均匀化处理时间呈明显指数函数特征,V1 130℃=0.033 5exp(-0.163 1t).