Diffusion Bonding of 17-4 Precipitation Hardening Stainless Steel to Ti Alloy With and Without Ni Alloy Interlayer: Interface Microstructure and Mechanical Properties

In the present study, the diffusion bonding of 17-4 precipitation hardening stainless steel to Ti alloy with and without nickel alloy as intermediate material was carried out in the temperature range of 1073 K to 1223 K (800 °C to 950 °C) in steps of 298 K (25 °C) for 60 minutes in vacuum. The effects of bonding temperature on interfaces microstructures of bonded joint were analyzed by light optical and scanning electron microscopy. In the case of directly bonded stainless steel and titanium alloy, the layerwise α-Fe + χ, χ, FeTi + λ, FeTi + β-Ti phase, and phase mixture were observed at the bond interface. However, when nickel alloy was used as an interlayer, the interfaces indicate that Ni₃Ti, NiTi, and NiTi₂ are formed at the nickel alloy-titanium alloy interface and the PHSS-nickel alloy interface is free from intermetallics up to 1148 K (875 °C) and above this temperature, intermetallics were formed. The irregular-shaped particles of Fe₅Cr₃₅Ni₄₀Ti₁₅ have been observed within the Ni₃Ti intermetallic layer. The joint tensile and shear strength were measured; a maximum tensile strength of ~477 MPa and shear strength of ~356.9 MPa along with ~4.2 pct elongation were obtained for the direct bonded joint when processed at 1173 K (900 °C). However, when nickel base alloy was used as an interlayer in the same materials at the bonding temperature of 1148 K (875 °C), the bond tensile and shear strengths increase to ~523.6 and ~389.6 MPa, respectively, along with 6.2 pct elongation.     

Be/HR-1不锈钢扩散连接界面附近的元素扩散

为了优化热静压扩散连接工艺参数,应用有限元法对Be/HR-1不锈钢扩散连接界面附近铁和铍元素的分布进行了计算机模拟,并通过俄歇电子能谱(AES)进行实验测定。结合计算机模拟结果和实验数据探讨了扩散连接界面附近铁和铍元素的分布、扩散宽度与温度、压力和时间的关系。结果表明:在1050℃/60 MPa/2 h和750℃/60 MPa/2 h热静压下,扩散连接界面附近Be,Fe元素分布的实测数据与计算机模拟结果基本吻合;在60 MPa/2 h热静压下,加热温度分别为1050和750℃时对扩散宽度影响的实测数据与计算机模拟结果基本吻合,1050℃时的扩散宽度是750℃时的2.5倍;在750℃/2 h热静压下,压力分别为30,40,50,60 MPa时对扩散宽度影响的实测数据与计算机模拟结果基本吻合,扩散宽度与压力成抛物线关系;在750℃/60 MPa热静压下,扩散宽度与扩散时间的模拟曲线也成抛物线关系。     

Bonding Interface Formation between Mg Alloy and Steel by Liquid-phase Bonding using the Ag Interlayer

Liquid-phase bonding between a Mg alloy (AZ31) and low-carbon steel was attempted at 773 K (500 °C) using Ag as an interlayer that forms a eutectic melt with the Mg alloy at this temperature. On the AZ31 side, eutectic melting and subsequent isothermal solidification were observed, and it was confirmed that the solidification of the eutectic liquid was promoted by the diffusion of Ag into the AZ31 base metal. On the steel side, Al was transported from AZ31 during the eutectic melting and isothermal solidification. This transported Al was enriched at the steel surface and reacted with steel to form a uniform, thin Fe-Al intermetallic compound layer. After the isothermal solidification, strong bonding was achieved via the thin intermetallic compound layer between AZ31 and steel, and no Ag remained at the bonding interface. The strength of the joint was found to be higher than the yield strength of AZ31.     

纳米镀镍层作中间层的钛合金与不锈钢扩散焊接

采用电镀纳米镍中间层,对钛合金TA17与不锈钢0Cr18Ni9Ti进行扩散焊焊接试验研究.利用能谱对焊接接头的元素分布进行分析,结果表明:采用电镀纳米镍层作中间层能有效防止钛合金中的Ti、V、Al等元素与不锈钢中Fe、Ni、C等元素的相互扩散和迁移,很好地抑制了金属间化合物TiFe、TiFe2及脆性相TiC的形成.通过计算接头处扩散层的激活能可知纳米镍的扩散性能比镍箔的好.     

Transient-Liquid-Phase Bonding of H230 Ni-Based Alloy Using Ni-P Interlayer: Microstructure and Mechanical Properties

Transient-liquid-phase bonding using Ni-P as an interlayer has been developed for H230 Ni-Cr-W solid-solution-strengthened Ni-based alloy. Two process parameters—composition of the interlayer and bonding time—have been varied to optimize the mechanical properties. H230 has been bonded into two sets of stacks (set I and II) for 8 and 4 hours using Ni-12P and Ni-6P interlayer, respectively, (wt pct) at 1423 K (1150 °C) and 12.7 MPa. The microstructure of both the stacks has three distinct regions—the joint centerline which showed the presence of pores, an isothermally solidified zone (ISZ) which did not have any carbide precipitates and base H230. Transmission electron microscopy and atom probe tomography showed a uniform microstructure, and an absence of any deleterious phases at the joint and in ISZ. Set I and set II had a yield strength of 76 and 86 pct of that of the H230 sheet, tested at 1023 K (750 °C). The measured elongation at fracture was negligible, but the fracture surfaces revealed a ductile cup-and-cone-type fracture occurring through the ISZ/joint region. Examination of broken tensile samples revealed that the plastic strain was constrained to within one joint region through which fracture occurred.     

钛合金-不锈钢相变超塑性扩散连接接头分析

探讨了TA17钛合金和OCr18Ni9Ti不锈钢相变超塑性扩散连接工艺；分析了接头微观组织结构，元素的扩散及断口形貌。结果表明，钛合金和不锈钢两侧的元素有不同程度的扩散，在界面处形成β-Ti、TiFe和TiFe2。控制金属间化合物厚度在5μm以内可以提高接头强度。接头受力的主要物相是以β-Ti为基的固溶体，该物相的面积对接头的强度影响很大，面积越大，接头强度越高；反之越低。     

Microstructure and Mechanical Properties of Electroslag Strip and Explosively Clad Low Alloy Steel: Stainless Steel Joints

The surface properties such as wear, corrosion, oxidation resistance etc., can be improved by using suitable cladding technique. The most commonly used cladding material is stainless steel for cladding on carbon and low alloy steel base materials. Mechanical properties are considered important for satisfactory performance of clad joints used in several defence applications. In this work, cladding of a high strength low alloy steel with stainless steel was carried out using explosive cladding and electroslag strip cladding processes. The relationship between mechanical properties and microstructure of clad materials was evaluated. The bond interface in explosively clad material shows a wavy interface compared to strip clad interface. Electron probe microanalysis revealed that inter-diffusion of elements was significant in strip clad joints and insignificant in explosively clad joints. Shear strength, notch tensile strength and impact toughness of explosive clad joints are much superior compared to those in strip clad joints.     

Impulse Pressure Assisted Diffusion Bonding of Low Carbon Steel Using Silver Interlayer

In the present study, impulse pressure assisted diffusion bonding of low carbon steel was carried out using silver interlayer. To study the influence of input process parameters namely bonding temperature (T), maximum pulse pressure (P), and number of pulses (N), experiments of diffusion bonding were conducted according to the Taguchi L9 orthogonal array. To reveal the typical bond interface characteristics, selected samples were examined by scanning electron microscopy (FESEM) equipped with energy dispersive spectroscopy (EDS). The EDS analysis revealed a diffusion affected zone at the interface due to the diffusion of silver and iron across the interface. Lap joints were developed to measure the shear strength of the diffusion bonds. The optimum level of bonding temperature, maximum pulse pressure and number of pulses (875 °C, 10 MPa and 10 pulses) were identified. The ANOVA results indicated that bonding temperature had the highest statistical effect of 66.37% on shear strength followed by number of pulses and maximum pulse pressure. The fracture surface of the lap joints was also examined by FESEM and X-ray diffraction analysis.     

Possibility to Strengthen the Joint between a Titanium Alloy and Stainless Steel Formed by Diffusion Welding through an Interlayer

The mechanical properties and the fracture of the joints between a PT3V titanium alloy and 12Cr18Ni10Ti stainless steel formed by diffusion welding through ultrafine-grained layers of nickel and a Cr2Ni98 alloy are studied. The highest strength of the joint (about 390 MPa) is achieved upon welding at T = 700°C, 20 min irrespective of the interlayer material. However, in the case of the nickel interlayer, fracture occurs in the regions adjacent to the TiNi layer; in the case of the Cr2Ni98 alloy, along the alloy/steel interface.     

合金元素对2Cr13马氏体不锈钢组织及性能的影响

Ni,Mo,V均是影响13Cr型马氏体不锈钢性能的主要元素.研究了在普通2Cr13基础上添加不同含量的Ni,Mo以及微量V对其力学性能、耐腐蚀性能的影响.研究表明:单独添加Ni或Mo元素均未能明显改善2Cr13型马氏体不锈钢的综合力学性能,但同时添加适量的Ni,Mo等合金元素能明显提高材料的力学及耐CO2腐蚀性能.     

反向凝固复合不锈钢带的轧制工艺及界面结合

针对用反向凝固法生产不锈钢复合带的工艺,研究了轧制温度、轧制速度及轧制变形率对母带与凝固层间结合的影响。结果表明：轧制温度为１２５０℃、两道次的轧制变形率为５０％时,界面结合较好,轧制速度对界面结合的影响不明显。经分析得知 喧与凝固层的界面结合是靠元素相互扩散形成过渡区实现的。     

Ti60高温钛合金环材组织与性能的研究

研究了Ti60高温钛合金环材的组织和性能。结果表明,该合金环材经双重退火后的显微组织为双态组织,并含有强化相α2相及硅化物相;这种组织的环材具有良好的室温拉伸、高温拉伸、热稳定、蠕变和断裂韧性等性能匹配,它的各项主要性能与IM I834钛合金相当,可用于制作航空发动机压气机压气盘、叶片等构件。     

Interfacial Microstructure of Al-Sn-Pb Alloy/Steel During Liquid-Solid Bonding Rolling

Studies were conducted on the interfacial microstructure of a steel/liquid aluminium and its evolution during the bonding rolling process. The effects of wetting time and deformation on the diffusion layer and on the bonding strength were examined. By means of electron microscopy and electron probe analysis, it was found that the diffusion layer is mainly composed of FeAI3. For a steel temperature of 250℃ and an aluminium temperature of 850 ~C, the diffusion layer was formed within 3 s, and the shear strength of the samples increased after 8 to 14 s. Although the interface was not damaged, it was deformed notably. For an aluminium temperature of 750℃ and a wetting time of 11 to 17 s, the shear strength of the interface remained high, but the interface was obviously broken during rolling, leading to reduced bonding strength.     

Ti/N对低碳贝氏体钢组织和力学性能的影响

研究了Ti/N对一种工程机械用高强度低碳贝氏体钢组织和力学性能的影响.研究结果表明,Ti/N值可明显影响钢中酸溶硼的收得率和力学性能.Ti/N在3.3以下时,酸溶硼的收得率小于50％;Ti/N大于3.6时酸溶硼收得率在75％以上;Ti/N超过4时,酸溶硼的收得率趋于90％,并不再有明显提高.随Ti/N的增加钢板的性能合...     

钛合金超塑成形/扩散连接的数值模拟及工艺研究

利用有限元软件Marc对钛合金TC4板的超塑成形/扩散连接(SPF/DB)进行数值模拟.通过模拟获得优化的压力-时间(p-t)曲线,为后续的超塑成形/扩散连接试验提供参考基础.经过试验得到钛合金TC4板超塑成形/扩散连接的最佳工艺参数为:超塑成形,θ=900 ℃、p=2.5 MPa、t=790 s;扩散连接,θ=900 ℃、p=3.0 MPa、t=80 min. 钛合金TC4;超塑成形/扩散连接(SPF/DB);数值模拟;工艺研究     

Microstructure and Wear Behaviour of 17-4 Precipitation Hardening Stainless Steel with Various Ti Content

Powder Metallurgy and Metal Ceramics - In this study, the wear behaviour of aged 17-4 PH SS (precipitation hardening stainless steel) that contains 0.5, 1, 1.5, and 2% of Ti was examined. The mixed...     

Effect of Stress Relief Annealing on Microstructure & Mechanical Properties of Welded Joints Between Low Alloy Carbon Steel and Stainless Steel

Metallurgical and Materials Transactions A - Two types of welded joints were prepared using low alloy carbon steel and austenitic stainless steel as base materials. In one variety, buttering...     

Accumulative Roll Bonding of Alloy 2205 Duplex Steel and the Accompanying Impacts on Microstructure,Texture, and Mechanical Properties

Metallurgical and Materials Transactions A - The mechanical and microstructural evolution of Alloy 2205 during severe plastic deformation is examined in this study. A combination of accumulative...     

液-固相轧制复合法生产含硅中锡/钢复合轴瓦带的凝固组织

采用液—固相轧制法可以稳定、连续生产AlSn8Si2．5Pb2Cu0．8Cr0．2覆钢双层轴瓦带。通过金相照片显示其组织与铸造组织相似，但柱状晶(胞状晶)更为细小、发达，组织内Si，Sn等元素分布均匀，在液—固相轧制复合工艺条件范围内，浇注温度对胞状晶组织结构有较大影响，退火则使Sn，Si元素聚集、球化。     

Influence of Ti on Weld Microstructure and Mechanical Properties in Large Heat Input Welding of High Strength Low Alloy Steels

The influence of Ti on weld microstructure and mechanical properties in large heat input welding of high strength low alloy steels is investigated.The results indicate that a moderate amount of Ti is still effective for grain refinement even under larger heat input and a large amount of acicular ferrite(AF)is formed in the weld metal when Ti content is within 0.028%-0.038%.With increasing Ti content,proeutectoid ferrite in the weld metal decreases,whereas bainite and M-A constituent increase.The type of inclusion in the welds varies from Mn-Si-Al-O to TiMn-Al-O and finally to Ti-Al-O as Ti content increases from 0up to 0.064%.As for adding 0.028%-0.038% Ti,high weld toughness could be attained since most inclusions less than 2μm which contain Ti2O3 provide the effective nuclei for acicular ferrite formation.However,the toughness of the weld metals severely reduces when Ti content is over the optimum range of 0.028%-0.038%.