大规格TC4板材冷轧工艺研究

介绍了大规格TC4板材冷轧生产工艺,分析了宽幅TC4合金板冷轧生产技术要点。研究表明：冷轧4.0 mm厚TC4板材厚度公差可控制±0.05 mm,整体不平度≤3 mm;生产过程中,TC4板材容易出现边部开裂现象,但通过控制退火制度和轧程变形量可有效解决此问题;规格为4.0 mm×1 500 mm×4 000 mm的大规格TC4板材各项性能指标完全满足ASM4911H标准要求。     

再结晶退火对TC4合金板材性能的影响

研究了在不同温度与不同时间下TC4合金板材的再结晶退火对其显微组织和室温力学性能的影响。利用再结晶退火消除加工硬化和调节显微组织,使其达到较好的室温力学性能,总结出TC4合金板材较合理的再结晶退火制度。     

温度对AgCu/光滑TC4体系润湿铺展动力学的影响

研究了试验温度对AgCu/光滑TC4钛合金体系的润湿铺展动力学的影响,实验过程采用座滴法,全程高纯氩气保护。结果表明,试验温度的升高明显促进了AgCu/光滑TC4体系的润湿性和界面反应。当试验温度为1103和1133 K时,AgCu钎料在TC4基板上的润湿铺展过程相似,整个润湿铺展过程大致可分为4个阶段:初始阶段,快速铺展阶段,缓慢铺展阶段和渐进平衡阶段。当试验体系温度为1213 K,化学反应更为强烈,AgCu钎料在TC4基板上的润湿铺展速度明显地加快,整个润湿铺展过程缩短至3个阶段:初始阶段,快速铺展阶段和渐进平衡阶段。试验温度为1103和1133 K时,钎料熔敷/母材的界面结构均为残余的富银相/Ti_3Cu_4/富钛相+Ti_2Cu/TC4基板;当试验温度为1213 K时,其界面结构转变为残余的富银相/Ti_3Cu_4/Ti_2Cu/富钛相+Ti_2Cu/TC4基板。且随着温度的升高,各个界面反应层的厚度均增加,残余的富银相厚度减小。AgCu钎料在光滑TC4基板上的润湿铺展动力学遵循Rn~t模型,试验温度不同,n值有所变化。     

超低间隙TC4-DT钛合金厚板显微组织与力学性能研究

研究了固溶+时效处理对超低间隙TC4-DT钛合金厚板显微组织和力学性能的影响。结果表明,固溶温度会显著影响TC4-DT钛合金厚板组织中初生α相和次生α相的含量及尺寸,提高固溶温度可以适当提高板材的强度及断裂韧度。固溶处理冷却速率较快时(水冷和空冷),会析出细针状和板条状的片层组织,主要提高板材的断裂韧度。当固溶温度为945℃,且经水冷或空冷后可以获得强度-塑性-韧性匹配良好的TC4-DT钛合金厚板。     

利用成分不良的TC4钛合金铸锭制备合格板材的工艺研究

为了充分利用某批因添加回收料较多而造成O含量较高或不均匀的TC4钛合金铸锭,以该批铸锭为研究对象,研究了不同锻造工艺对锻坯组织及成品板材力学性能的影响。结果表明:经三火次锻造获得的7 mm厚热轧板材的力学性能不稳定且有较多不合格;经六火次锻造可获得以等轴和短棒状α相为主的双态组织,轧制后得到的4.5mm厚成品板材的伸长率可达12.5%~19%,且强度较高;经四火次锻造可获得以长条状α相为主的组织,轧制后得到的4.5 mm厚成品板材性能合格,伸长率为12.5%~17%。综合分析知,通过四火次锻造加三火轧制可得到组织均匀、性能稳定的TC4钛合金成品板材,实现对O含量较高或波动较大的TC4钛合金铸锭的应用,且生产成本较低。     

形状比对TC4-DT钛合金厚板轧制变形渗透性影响规律

基于热模拟压缩试验得到的流变应力曲线,建立了TC4-DT钛合金厚板单道次热轧模拟仿真平台,对不同压下率和形状比条件下的热轧过程进行仿真分析,以等效塑性应变为0.2作为透性衡量指标,研究了板坯厚度方向变形渗透规律。经拟合,得到TC4-DT钛合金轧制时形状比(SR)与变形渗透深度的经验公式为:y=29.1exp(3.2SR)-60.66。提高形状比可显著改善TC4-DT钛合金厚板心部的变形程度,提高板材的一次合格率。     

钛合金板材轧制力及轧制力矩计算

通过选择合适的板材轧制力计算公式,制定了三个不同的工艺方案,从理论上较为准确的得出了利用轧机热轧TC4钛合金板的轧制力和轧制力矩,旨在为Φ760轧机技术改造提供数据,并用于TC4合金实际热加工过程工艺参数的制定、优化及负荷计算、设备校核等。     

损伤容限型TC4-DT合金疲劳裂纹扩展速率的数学描述

测试了损伤容限型TC4-DT合金的裂纹扩展速率。通过数据分析和线性或非线性拟合得到了3种疲劳裂纹扩展速率的数学描述公式。通过对描述结果的误差分析，得到了描述板材疲劳裂纹扩展速率的理想描述公式。     

TC4钛合金板材热轧处理工艺改进研究

钛合金因其具有强的耐腐蚀性能、比强度高、稳定性能好、密度小等优势而应用于各行各业中,但钛合金因其导热率低、变形抗力大、成材率低、轧制成形困难等缺点限制了钛合金的发展。基于此,本文以TC4钛合金板材为研究对象,通过改进热轧工艺,提出TC4钛合金板材的加工安全温度为890℃～1000℃,失稳区范围为700℃～850℃。经过理论仿真模拟计算,本次实测数据与理论计算数据变化规律一致,说明本文所获结论是合理的。     

TC4钛合金与无氧铜、可伐合金真空钎焊工艺研究

针对红外探测器杜瓦冷指的设计,应选取具有较高屈服强度、较低热导率和较低密度的材料,以提高红外探测器杜瓦的可靠性。考虑到红外探测器封装的其他结构需求,TC4钛合金与无氧铜、可伐等金属之间的焊接一般不太容易实现,试验中采用真空钎焊作为焊接手段,选取Ti-Ni-Zr-Cu钎料,对TC4钛合金与无氧铜、可伐合金的真空钎焊焊接试验结果进行比较分析,得出TC4钛合金与无氧铜、可伐合金钎焊后检漏漏率优于10-11 torr.l/s,焊缝抗拉强度都达到150 MPa以上。     

Investigating crystallization processes while brazing copper by copper-phosphorus brazing alloy with the purpose of controlling the structure of the brased seam

The possibility of predicting the structure of a brazed seam is considered. The brazing temperature is selected as the main method of influence since the composition of the liquid brazing alloy in the seam for eutectic systems will be determined by the line of the liquidus of the phase diagram of the “brazing alloy-brazed material” system. The influence of nonequilibrium crystallization conditions on the structure of the brazed seam is established. It is found that it is insignificant for the Cu-P system due to a small variation in the phosphorus solubility in the solid phase during crystallization. A simple formula for determining the thickness of the brazed seam is suggested. The results of calculations are confirmed by the experiments of brazing copper by the copper-phosphorus brazing alloy. It is shown that it is possible to obtain any eutectic content in the brazing alloy seam and, consequently, vary the strength properties of the seam.     

Liquid Film Migration in Warm Formed Aluminum Brazing Sheet

Warm forming has previously proven to be a promising manufacturing route to improve formability of Al brazing sheets used in automotive heat exchanger production; however, the impact of warm forming on subsequent brazing has not previously been studied. In particular, the interaction between liquid clad and solid core alloys during brazing through the process of liquid film migration (LFM) requires further understanding. Al brazing sheet comprised of an AA3003 core and AA4045 clad alloy, supplied in O and H24 tempers, was stretched between 0 and 12 pct strain, at room temperature and 523K (250 °C), to simulate warm forming. Brazeability was predicted through thermal and microstructure analysis. The rate of solid–liquid interactions was quantified using thermal analysis, while microstructure analysis was used to investigate the opposing processes of LFM and core alloy recrystallization during brazing. In general, liquid clad was consumed relatively rapidly and LFM occurred in forming conditions where the core alloy did not recrystallize during brazing. The results showed that warm forming could potentially impair brazeability of O temper sheet by extending the regime over which LFM occurs during brazing. No change in microstructure or thermal data was found for H24 sheet when the forming temperature was increased, and thus warm forming was not predicted to adversely affect the brazing performance of H24 sheet.

     

Ni元素对Al-Si-Cu基真空钎焊料接头性能的影响

研究了添加Ni的Al-Si-Cu基钎料真空钎焊LF21铝合金接头的力学性能、微观组织形貌.结果表明,采用添加Ni元素的真空钎料,可提高钎焊接头的剪切强度,其机制在于Ni元素能够改善LF21铝合金真空钎焊接头焊缝及其基体组织的分布.但随着Ni元素含量的增加,其钎料的熔点也有所提高.     

Thermochemical Analysis of Phases Formed at the Interface of a Mg alloy-Ni-plated Steel Joint during Laser Brazing

The thermodynamic stability of precipitated phases at the steel-Ni-Mg alloy interface during laser brazing of Ni-plated steel to AZ31B magnesium sheet using AZ92 magnesium alloy filler wire has been evaluated using FactSage thermochemical software. Assuming local chemical equilibrium at the interface, the chemical activity–temperature–composition relationships of intermetallic compounds that might form in the steel-Ni interlayer-AZ92 magnesium alloy system in the temperature range of 873 K to 1373 K (600 °C to 1100 °C) were estimated using the Equilib module of FactSage. The results provided better understanding of the phases that might form at the interface of the dissimilar metal joints during the laser brazing process. The addition of a Ni interlayer between the steel and the Mg brazing alloy was predicted to result in the formation of the AlNi, Mg₂Ni, and Al₃Ni₂ intermetallic compounds at the interface, depending on the local maximum temperature. This was confirmed experimentally by laser brazing of Ni electro-plated steel to AZ31B-H24 magnesium alloy using AZ92 magnesium alloy filler wire. As predicted, the formation of just AlNi and Mg₂Ni from a monotectic and eutectic reaction, respectively, was observed near the interface.     

Manufacture of powders of nickel-base brazing alloys

Conclusions A process has been developed for the manufacture of a Ni-Cr-Si-Fe-B brazing alloy in powder form, designated as PKh12N75S8R, and also brazing alloy powder No. 6MA, which is a mechanical mixture of 85% of PKh12N75S8R powder and 15% of molybdenum. Using alloy powder No. 6MA (instead of PKh12N75S8R) for brazing high-alloy steels raises the secondary melting (unbrazing) temperature of the brazed joint.Translated from Poroshkovaya Metallurgiya, No. 5 (113), pp. 82–88, May, 1972.     

稀土元素对低温铝基钎料性能影响的研究

本文研究了稀土元素Ｙ、Ｃｅ对Ａｌ－Ｚｎ－Ｃｕ－Ｓｉ系列低温铝基钎料的熔化温度、钎焊工艺性、电极电位及其接头的机械性能及抗腐蚀性能的影响。结果表明：少量Ｙ、Ｃｅ的加入，对钎料的熔化温度影响不大，能提高钎料的钎焊工艺性；稀土Ｙ、Ｃｅ能细化晶粒，改变组织的分布状态，不改变钎料的电极电位，但却提高了钎焊接头的机械性能和抗腐蚀性。     

铝合金钎焊板(箔)热轧复合工艺研究

揭示基体金属和焊层金属在热轧时的复合机理及成形规律，根据金属轧制过程中的变形规律，研究了热轧过程中及冷轧过程中包覆层的厚比变化规律，研究了铝合金钎焊板(箔)热轧复合工艺，开发出满足使用要求的铝合金钎焊板(箔)。     

Structure of powder brazing alloys based on the system Ni-Cr-Si-Fe-B-C(-Mo)

Conclusions A study was made of the sinterability of PKh12N75S8R brazing alloy powder and a mechanical mixture of this powder with 15% of molybdenum (brazing alloy No. 6MA), which are widely used for the brazing of high-alloy steels. Appreciable shrinkage of compacts begins at 1000°C and steadily increases with rise in sintering temperature. The most intense shrinkage is observed above 1100°C, i.e., at temperature close to the solidus. The structure of brazing alloy No. 6MA produced by sintering at 1175–1200°C or melting consists of a solid solution and molybdenum suicides and chromium borides of various compositions.Translated from Poroshkovaya Metallurgiya, No. 10 (118), pp. 77–84, October, 1972.     

Development of a new CuNiTiB brazing alloy for joining Si3N4 to Si3N4

Joining Si₃N₄ to Si₃N₄ was carried out initially with a Cu₃₄Ni₂₇Ti₃₉ brazing alloy prepared by double melting under a vacuum condition. However, the strength of the joints was not as high as expected. The causes were studied. Based on the results of the analysis, a CuNiTiB brazing filler metal was designed. The Si₃N₄/Si₃N₄ joints were then brazed with this new brazing alloy in the paste form, and joints with a three-point bend strength of 338.8 MPa at room temperature were obtained. The interfacial reactions of the joint are also discussed. With the rapidly solidified foils of the brazing alloy, the bend strength of the Si₃N₄/Si₃N₄ joints under the same brazing conditions is raised to 402 MPa at room temperature. The Si₃N₄/Si₃N₄ joints brazed with this newly developed brazing alloy exhibit a rather high and steady bend strength (about 406 MPa) at 723 K.     

几种不同银基钎料对钛合金/不锈钢钎焊焊缝的影响

采用不同成分的钎料在相同温度、相同时间条件下，利用光学显微镜，扫描电子显微镜(SEM)等检测手段，对钛合金／不锈钢钎焊焊缝进行了观测分析，并对钎焊接头中形成的不同相的特征以及金属间化合物对接头结合性能的影响进行了分析探讨。