铸造用Ti-6.5Al-3.5Mo-1.5Zr-0.3Si高温钛合金的组织与力学性能

Ti-6.5Al-3.5Mo-1.5Zr-0.3Si合金经二次熔炼、锻造成棒材,然后再浇铸成试棒。介绍了这种合金的铸态室温及高温拉伸性能。试验表明,在600℃时的高温强度与塑性匹配较好,可用作为600℃高温结构件用。同时,分析了合金经不同制度热处理后的显微组织、室温拉伸、高温拉伸及持久性能变化。结果表明:合金在960℃×1.5 h,AC+550℃×8 h,AC处理后得到网篮组织,表现出良好的综合力学性能。     

Effect of Cold Rolling and Heat Treatment on Microstructure and Mechanical Properties of Ti-4Al-1Mn Titanium Alloy

Mechanical behavior of Ti-4Al-1Mn titanium alloy has been studied in annealed, cold-rolled and heat-treated conditions. Room temperature tensile strength as well as % elongation has been found to be low with increasing amount of cold rolling. Lowering of strength in cold worked condition is attributed to premature failure. However, the same has been mitigated after heat treatment. Significant effect of cooling media (air and water) from heat treatment temperature on microstructure was not found except for the degree of fineness of α plates. Optimum properties (strength as well as ductility) were exhibited by samples subjected to 15% cold rolling and heat treatment below β transus temperature, which can be attributed to presence of recrystallized microstructure. In cold worked condition, the microstructure shows fine fragmented α plates/Widmanstätten morphology with high dislocation density along with a large amount of strain fields and twinning, which gets transformed to recrystallized equiaxed microstructure and with plate-like morphology after near β heat treatment. Prior cold work is found to have a significant effect on mechanical properties supported by evolution of microstructure. Twinning is found to be assisting in deformation as well as in recrystallization through the formation of deformation and annealing twins during cold working and heat treatment. Fracture analysis of the tested sample with prior cold work and heat-treated condition revealed quasi-ductile failure as compared to only ductile failure features seen for samples heat treated without prior cold work.     

铁白铜焊接接头的组织和力学性能

对BFe10-1-1铁白铜管采用钨极氩弧焊打底 手工电弧焊盖面的焊接工艺,可获得性能良好的焊接接头;焊缝区的组织为树枝状偏析α固溶体,具有较强的抗腐蚀性;接头的各项力学性能完全满足要求.     

TC4钛合金激光焊接接头组织与性能

分析不同激光焊接工艺参数下焊缝的微观组织特征,并测试焊缝的力学性能.结果表明:TC4钛合金激光焊接焊缝为针状马氏体α'组成的网篮组织和少量α'相;随着焊接热输入量的增加,由于熔池搅拌、焊接应力、合金元素烧损等原因,马氏体的分布更加散乱和密集;焊接工艺参数对焊缝相组成和各相相对含量的影响均不显著.合理的焊接工艺参数下,接头的强度高于母材.     

Fatigue Performance of Gas Tungsten Arc, Electron Beam, and Laser Beam Welded Ti-6Al-4V Alloy Joints

Titanium alloys have been successfully applied for aerospace, ship, and chemical industries because they possess many good characteristics such as high strength to weight ratio, superior corrosion resistance, and excellent high temperature resistance. Though these alloys show reasonable weldability characteristics, the joint properties are greatly influenced by the welding processes. The evaluation and prediction of fatigue life are very important for the welded joints to avoid catastrophic failure particularly in titanium alloys. This article compares the fatigue performance of Ti-6Al-4V alloy fabricated by gas tungsten arc welding, laser beam welding, and electron beam welding processes. The resultant fatigue properties of the welded joints are correlated with the tensile properties and microstructural characteristics. Of the three processes considered the joint welded by laser beam welding exhibits higher fatigue limit when compared with the other two processes due to the presence of fine lamellar microstructure in the weld metal region.     

TC4钛合金摩擦焊接头的力学性能及显微组织

对钛合金TC4（Ti-6Al-4V）摩擦焊接性能进行了较详细的试验分析。结合摩擦焊接参数的优化选择,叙述了该合金摩擦焊接过程的特点,讨论分析了其焊接接头的力学性能及焊合区的显微组织结构。试验结果表明,该合金具有良好的摩擦焊接性,在无特殊保护措施的条件下,优化工艺,可获得良好的焊接接头。由于TC4钛合金导热系数小,热塑性高,容易氧化,摩擦焊亦选用较小的规范参数。焊合区硬度略低于母材,拉伸度样断于母材,拉伸、冲击断口均表现出明显的韧性断裂特性。力学性能数据表明,用优化的规范参数,TC4钛合金可获得等强、等韧甚至超强、超韧于母材的摩擦焊接接头。TC4钛合金摩擦焊接接头焊合区组织为细密的网蓝状组织,焊合区与母材过渡区为双态组织。     

激光成形修复Ti-6Al-4V钛合金零件的组织与性能

分析了激光成形修复Ti-6Al-4V合金的组织特点,并考察了退火处理对修复区组织及修复件性能的影响.激光修复件的微观组织由修复基体所具有的等轴α+层状α+β双态组织经热影响区连续转变为晶内分布魏氏α+β的外廷生长的粗大柱状晶组织.激光修复件的静载拉伸性能达到锻件标准.经退火处理后,修复区中α板条有粗化趋势,修复件的综合力学性能得到一定改善,塑性有所提高.经采用退火+喷丸处理,修复件的低周疲劳性能达到与锻件相当.     

Effect of Multiple Laser Shock Processing on Microstructure and Mechanical Properties of Ti-5Al-4Mo-4Cr- 2Sn-2Zr Titanium Alloy

对Ti-5Al-4Mo-4Cr-2Sn-2Zr钛合金进行了不同能量和冲击次数的激光冲击强化,通过残余应力、显微硬度、XRD和TEM分析其对力学性能和微观组织的影响。结果表明,功率密度和冲击次数对残余应力和显微硬度都有较大影响,激光冲击强化后,显微硬度和残余应力都有大幅度提升,并形成一定厚度的变形层,增加冲击次数或者增大功率密度都可提高其幅值和影响深度。不同冲击参数下的XRD测试表明,激光冲击强化后衍射峰位置没有发生变化,但有展宽。激光3次冲击后可在表面形成一层纳米晶,晶粒大小为30~60 nm,且取向随机。位错运动是Ti-5Al-4Mo-4Cr-2Sn-2Zr钛合金晶粒细化的主要原因。     

含铒铝合金激光焊接接头组织与性能研究

对含铒铝镁合金冷轧板进行了激光焊接,分析了接头的各区域的微观组织和力学性能,探讨了铒对焊缝及热影响区组织与性能的影响。结果表明:由于稀土元素Er的加入,使焊缝中心晶粒尺寸减小到30μm左右;熔合线附近出现"细晶层";热影响区晶粒未见明显长大;焊接接头焊缝截面的显微硬度呈W形分布;Er对焊接接头的抗拉强度提高并不明显,接头抗拉强度为母材的70%。     

6082铝合金MIG焊焊接接头组织与力学性能研究

通过拉伸、弯曲、硬度试验以及金相分析等对6082铝合金MIG焊接头的力学性能与显微组织进行了研究。结果表明:采用5087焊丝焊接6082铝合金时,具有较好的抗拉性能,板厚8和4mm的焊接接头焊态的抗拉强度分别为母材的77.8%和73%;弯曲断裂集中在熔合线处,弯曲角度均较小;6082铝合金MIG焊接头焊缝中心组织为等轴晶,靠熔合线的焊缝晶粒沿散热方向呈柱状晶,熔合区晶粒粗大;软化区出现过时效效应,使Mg2Si长大,成为接头最薄弱的区域。     

热输入对双光束激光焊接Ti-6Al-4V合金T型接头焊接过程、焊缝成形、组织及力学性能的影响

采用双光束同步激光填丝焊接的方法制备了Ti-6Al-4V合金T型接头,使用高速摄像机拍摄了焊接过程图像并研究了热输入对焊接过程稳定性、焊缝成形、组织及力学性能的影响。试验结果表明,热输入显著影响熔池行为和填丝焊接熔滴过渡,进而影响T型接头焊缝形貌及质量。随着热输入的增加,T型接头组织发生变化,晶粒尺寸变大。热影响区及焊缝处的马氏体使得这2个区域的显微硬度高于母材。另外,沿蒙皮方向及筋条方向的抗拉伸强度随着热输入的增加而增大。由于接头处马氏体增强作用,拉伸断裂均发生于母材处。     

等离子冷床炉单次熔炼制备Ti-2Al-1.5Mn合金

主要介绍了等离子冷床炉单次熔炼制备Ti-2Al-1.5Mn钛合金铸锭在化学成分、组织、内部品质等方面的情况。结果表明,首次使用PAM炉单次熔炼法制备出航空领域工业级厚330mm、宽750mm、长1 000~2 500mm的钛合金扁锭,其化学成分可控且均匀性较好,纵横向组织均匀细小。此外,获得PAM炉单次熔炼法制备的钛合金扁锭全截面低倍组织图谱特征。铸锭经加工变形后获得的板材产品理化性能满足技术要求。     

时效处理对Ti-22Al-25Nb合金线性摩擦焊接头组织和力学性能的影响

对Ti-22Al-25Nb合金线性摩擦焊接头进行840 ℃×2 h的时效处理,研究了焊接头的组织和力学性能。结果表明,焊接头主要分为3个区域,分别是焊缝区、热力影响区和母材区。焊缝区组织以B2相为主,α2相和O相的数量相对较少。热力影响区仅有少量的α2相和O相转变为B2相,且α2相形态变化不大。EBSD分析结果表明,母材的晶体学取向无法遗传到最终的焊缝组织中。经过840 ℃时效处理后,焊缝区发生了动态再结晶并析出了O相。在热力影响区,α2相的分解并不充分,可以观察到rim-O相围绕α2相析出。母材区O相有所长大,而α2相的形态无明显变化。时效处理之后细晶强化与O相的析出强化作用显著提高了焊接头的力学性能。     

1420铝锂合金双光点激光焊接头组织性能

在2mm厚1420铝锂合金双光点激光焊接试验的基础上,研究接头的组织与性能。对比分析单、双光点激光焊接头各区域的组织、显微硬度及室温拉伸力学性能,并观察断口形貌。结果表明:1420铝锂合金双光点激光焊接头组织与单光点激光焊接头组织分布类似,从熔合区至焊缝中心依次是等轴细晶、柱状晶和等轴树枝晶,但较单光点接头细化;双光点激光焊接头各区域硬度低于母材,但高于单光点激光焊接头;双光点激光焊接头焊态抗拉强度较母材下降,但略高于单激光焊接头,可达母材的86%。     

氯化法生产四氯化钛中泥浆的回收处理

用机械合金化工艺制备了Ａｌ－１２Ｔｉ－６Ｎｂ合金，对其物相组成和显微组织进行了ＸＲＤ、电子探针和金相分析与观察，测试了其室温力学性能，并用ＳＥＭ观察了断口形貌，结果表明：ＭＡ Ａｌ－１２Ｔｉ－６Ｎｂ合金中生成了粗细不均的Ａｌ３Ｔｉ金属间化合物粒子，但未形成Ａｌ３Ｎｂ；在较大的Ａｌ３Ｔｉ颗粒和Ｎｂ趋向于平行热压面分布。Ｎｂ的加入使合金较好地发挥了大个Ａｌ３Ｔｉ和盘状Ｎｂ颗粒的协同补强增韧作用，三点弯     

铂基合金与GH3128合金电子束焊接接头组织与性能研究

采用电子束焊接技术对铂基合金与GH3128进行焊接。利用工业CT、扫描电子显微镜、显微硬度仪和材料万能试验机,研究了铂基合金与GH3128焊接接头显微组织、力学性能及断口形貌。结果表明:铂基合金与GH3128具有良好的焊接性能,焊接接头的质量良好,无缺陷,成分均一,焊缝区显微硬度在360~380之间,焊缝强度为499 MPa,断裂方式为韧性断裂,断裂位置位于铂基合金一侧。     

TC4钛合金活性激光焊焊缝成形及组织性能

选取CaF₂、NaF和Na₂SiF₆作为活性剂对TC4钛合金进行活性激光焊接,在焊接过程中利用高速摄像机采集焊件上方的光致等离子体图像,焊后借助光学显微镜测量焊缝熔深和熔宽,利用EBSD观察分析焊缝显微组织,采用能谱仪测试焊缝元素组成,测试接头硬度和抗拉强度。结果表明,由于活性剂改变了焊件表面状态和压缩光致等离子体面积从而提高了激光吸收率,这使得焊缝熔化区面积增加;活性剂均可以使未熔透焊缝的熔深增加,正面熔宽减小,熔透焊缝正面熔宽减小,中部和背面熔宽均增加,3种活性剂中Na₂SiF₆对TC4钛合金激光焊焊缝成形的影响最明显;活性剂对焊缝下部显微组织影响不大,涂敷CaF₂和NaF后,焊缝上部β柱状晶的生长方向与未涂敷焊缝β柱状晶生长方向都指向焊缝表面,涂敷Na₂SiF₆焊缝上部β柱状晶的生长方向指向焊缝中心。涂覆CaF₂焊缝针状马氏体α′形态变化不明显,涂敷NaF的针状马氏体α′变得稍细,而涂敷Na₂SiF₆的针状马氏体α′变得短且细,较涂敷CaF₂和NaF的焊缝变化最明显。涂敷Na₂SiF₆的接头抗拉强度提高约12.5%,从改善焊缝成形和提高接头力学性能考虑,Na₂SiF₆可作为TC4钛合金激光焊的首选活性剂。     

ZK60镁合金CO2激光焊接接头的组织与性能

采用CO2激光对轧制态细晶粒ZK60镁合金板材进行了焊接.研究了焊接工艺参数对接头显微组织和力学性能的影响规律,并分析了细晶粒镁合金板材的焊接特点.结果表明,在合适的工艺条件下,可以获得成形性能良好,无半熔化区(PMZ)液化裂纹的焊接接头;其抗拉强度和伸长率达到了295 MPa,11.7％,分别为母材的91％和62％;熔池(FZ)边界处的胞状晶和柱状晶区范围较窄,约为20 μm,熔池区由细小的等轴晶构成;从熔池区(FZ)到热影响区(HAZ)再到母材(BM)晶粒尺寸差别在3 μm以下,焊接接头呈韧性断裂模式.     

Microstructure and Mechanical Properties of Laser Solid Formed Ti-6Al-4V Alloy Under Dynamic Shear Loading

To investigate the mechanical properties of the Ti-6Al-4V alloy fabricated by laser solid forming technology, both static and dynamic shear tests were conducted on hat-shaped specimens by a servohydraulic testing machine and an enhanced split Hopkinson pressure bar system, over a temperature range of 173-573 K. The microstructure of both the original and deformed specimens was characterized by optical microscopy and scanning electron microscopy. The results show that: (1) the anisotropy of shear properties is not significant regardless of the visible stratification and the prior-β grains that grow epitaxially along the depositing direction; (2) the ultimate shear strength of this material is lower than that of those Ti-6Al-4V alloys fabricated by forging and extrusion; (3) the adiabatic shear bands of approximately 25.6-36.4 μm in width can develop at all selected temperatures during the dynamic shear deformation; and (4) the observed microstructure and measured microhardness indicate that the grains become refined in adiabatic shear band. Estimation of the temperature rise shows that the temperature in shear band exceeds the recrystallization temperature. The process of rotational dynamic recrystallization is considered to be the cause of the grain refinement in shear band.     

镁合金电子束焊接头性能及微观组织分析

采用电子束焊接MB2镁合金,研究了焊接参数对镁合金焊缝深宽比的影响规律,分析了镁合金焊接接头的力学性能及微观组织.结果发现,焦点位置和扫描图形对焊缝深宽比有很大的影响;利用圆形扫描图形、2000Hz扫描频率、电子束散焦焊接镁合金可以得到性能优良、无裂纹、气孔等焊接缺陷的优质接头,焊缝内部组织为均匀细小的等轴晶,接头抗拉强度达到235MPa,为母材强度的92％.