Diffusion Bonding of Microduplex Stainless Steel and Ti Alloy with and without Interlayer: Interface Microstructure and Strength Properties

The interface microstructure and strength properties of solid state diffusion bonding of microduplex stainless steel (MDSS) to Ti alloy (TiA) with and without a Ni alloy (NiA) intermediate material were investigated at 1173 K (900 °C) for 0.9 to 5.4 ks in steps of 0.9 ks in vacuum. The effects of bonding time on the microstructure of the bonded joint have been analyzed by light optical microscopy and scanning electron microscopy in the backscattered mode. In the direct bonded joints of MDSS and TiA, the layer-wise σ phase and the λ + FeTi phase mixture were observed at the bond interface when the joint was processed for 2.7 ks and above holding times. However, when NiA was used as an intermediate material, the results indicated that TiNi₃, TiNi, and Ti₂Ni are formed at the NiA-TiA interface, and the irregular shaped particles of Fe₂₂Mo₂₀Ni₄₅Ti₁₃ have been observed within the TiNi₃ intermetallic layer. The stainless steel-NiA interface is free from intermetallics and the layer of austenitic phase was observed at the stainless steel side. A maximum tensile strength of ~520 MPa, shear strength of ~405 MPa, and impact toughness of ~18 J were obtained for the directly bonded joint when processed for 2.7 ks. However, when nickel base alloy was used as an intermediate material in the same materials, the bond tensile and shear strengths increase to ~640 and ~479 MPa, respectively, and the impact toughness to ~21 J when bonding was processed for 4.5 ks. Fracture surface observations in scanning electron microscopy using energy dispersive spectroscopy demonstrate that in MDSS-TiA joints, failure takes place through the FeTi + λ phase when bonding was processed for 2.7 ks; however, failure takes place through σ phase for the diffusion joints processed for 3.6 ks and above processing times. However, in MDSS-NiA-TiA joints, the fracture takes place through NiTi₂ layer at the NiA-TiA interface for all bonding times.     

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...     

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.     

合金元素对0Cr17Ni4Cu4Nb不锈钢组织与力学性能的影响—镍（4）

实验室研究了Ni含量对0Cr17Ni4Cu4Nb不锈钢组织与力学性能的影响,通过力学性能测试和金相显微组织和TEM结构分析,研究结果表明：随Ni含量的增加,δ-铁素体含量减少,As点降低;在相同回火温度下,随Ni含量的提高,强度增加。随淬火冷却速度的降低,强度下降,且Ni含量越高,强度下降的幅度越小;随时效后冷却速度的降低,强度增加,且Ni含量越高,强度增加的幅度越大。Ni含量控制在中上限容易满足技术条件的要求。     

0Crl7Ni4Cu4Nb沉淀硬化不锈钢锻造裂纹分析

实验室分析了0Cr17Ni4Cu4Nb不锈钢锻件的锻造裂纹产生原因,通过金相和扫描电镜观察,结果表明:Nb元素的偏析是引起锻造裂纹重要因素;Cu元素的偏析将在高温阶段析出大量的富铜相,导致高温塑性降低,也是导致锻造裂纹的原因之一。     

合金元素对0Cr17Ni4Cu4Nb不锈钢组织与力学性能的影响—铬(2)

实验室研究了Cr含量对0Cr17Ni4Cu4Nb不锈钢组织与力学性能的影响,通过力学性能测试和金相显微分析,研究结果表明:随Cr含量的增加,容易产生δ铁素体,引起C、Cr等元素的偏析,使As点、Mf点降低,且Mf点可降到室温以下,导致强度降低、塑性、韧性增加;随淬火冷却速度的降低,强度降低,塑性增加;随时效冷却速度的降低,强度增加;选择下限的Cr含量容易满足技术条件要求。     

合金元素对0Cr17Ni4Cu4Nb不锈钢组织与力学性能的影响—碳(1)

实验室研究了C含量对0Cr17Ni4Cu4Nb不锈钢组织与力学性能的影响,通过力学性能测试和金相显微分析,研究结果表明:随C含量的增加,As点、Mf点降低,且Mf点可降到室温以下,导致强度降低,塑性、韧性增加;随淬火冷却速度的降低,强度降低,塑性增加;随时效冷却速度的降低,强度增加;选择低的C含量容易满足技术条件要求。     

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.     

时效处理对05Crl7Ni4Cu4Nb马氏体沉淀硬化不锈钢力学性能及组织的影响

试验研究了 1040 ℃固溶的马氏体沉淀硬化不锈钢05Cr17Ni4Cu4Nb在480~620 ℃时效5 h的组织,强度和硬度。结果表明,随时效温度升高,马氏体基体逐渐分解,碳化物析岀而降低;在时效处理过程中,随时效温度升高,富Cu相最初以球形析出,逐渐发展成椭圆形及杆状,尺寸增大,与基体共格界面消失,强化效果减弱;05Cr17Ni4Cu4Nb钢经1040 °C固溶,480 °C 5h时效后,其HRC硬度值44.3,满足钢材HRC硬度值43的要求。     

节镍型奥氏体不锈钢1Cr17Mn9Ni4N的组织和力学性能

从热处理工艺对室温拉伸性能的影响和试验温度对拉伸性能的影响两个方面分析了1Cr17Mn9Ni4N钢组织和力学性能之间的关系。试验结果表明：随着固溶处理温度(950～1075℃)的提高,强度降低、塑性提高;水冷或空冷对力学性能的影响不大;材料的锻比对力学性能具有一定的影响;与同类钢相比,1Cr17Mn9Ni4N钢具有优异的室温和低温力学性能。该钢在低温变形时的TRIP效应是低温综合力学性能良好的根本原因。     

时效温度对马氏体沉淀硬化不锈钢0Cr15Ni5WMoVNb力学性能的影响

0Cr15Ni5WMoVNb钢(%:0.068C、14.54Cr、5.32Ni、0.88W、0.92Mo、0.20V、0.10Nb)经5 t中频感应炉+2 t真空电渣重熔炉冶炼,经锻造、热轧成Φ45 mm棒材,试样经1 000℃30 min固溶空冷+-70℃2 h冷处理后进行400～600℃4 h时效空冷。试验结果表明,在450℃时效0Cr15Ni5WMoVNb钢的强度最大,以准解理断裂为主,冲击功低为40 J,随时效温度上升,冲击功显著上升,强度下降,在510℃时效该钢有良好的强韧性,抗拉强度R_m 1300 MPa,屈服强度R_(p0.2)1100 MPa,冲击能A_(KV) 100 J。     

合金元素-铌对0Cr17Ni4Cu4Nb不锈钢组织与力学性能的影响

实验室研究了Nb含量对0Cr17Ni4Cu4Nb不锈钢组织与力学性能的影响,通过力学性能测试和金相显微分析,研究结果表明：随Nb含量的增加,强度增加,塑性降低;随时效温度的升高,强度下降,上限Nb含量试验料的强度下降较缓;随淬火冷却速度的降低,强度下降;随时效后冷却速度的降低,强度增加;Nb含量控制在中限容易满足技术条件的要求。     

合金元素对0Cr17Ni4Cu4Nb不锈钢组织与力学性能的影响—铜（3）

实验室研究了Cu含量对0Cr17Ni4Cu4Nb不锈钢组织与力学性能的影响,通过力学性能测试和金相显微分析,研究结果表明：在淬火冷却速度较快的情况下,随Cu含量的增加,强度增加,塑性下降;随淬火冷却速度的降低,强度下降,且Cu含量越高,强度下降的幅度越大;在淬火缓冷情况下,Cu含量对强度的影响不大;随时效后冷却速度的降低,强度增加;Cu含量控制在中下限容易满足技术条件的要求。     

化学成分和固溶温度对1Cr17Mn9Ni4N不锈钢组织和性能的影响

为提高1Crl7Mn9Ni4N钢固溶处理后的力学性能(特别是钢的强度)，研究了化学成分及固溶处理温度对其组织和性能的影响。结果表明，1000—1125℃固溶处理后，该钢的组织为单相奥氏体。在标准成分范围内，随着镍、锰含量的增加，该钢的强度降低，塑性有所改善。氮明显提高该钢的强度。根据试验结果，每增加0．01％的氮钢的室温强度可提高大约5MPa，且塑性基本上不受影响。当合金成分(质量分数，％)控制在C0．08—0．12、Crl6．5—17．5、Ni3．5—4．2、Mn8．0—9．0、N0．22—0．28时，1Crl7Mn9Ni4N钢经1050—1100℃固溶处理后强度较高、塑性好，室温强度σ0．2和σb可分别达到400MPa和800MPa。     

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。     

沉淀硬化不锈钢机械能助渗铝的试验研究

通过机械能助渗铝工艺,实现对沉淀硬化不锈钢的低温渗铝.500℃渗铝10 h,可以在保证基体材料的力学性能基本无损耗的情况下,得到厚度约为11μm的均一渗铝层.采用SEM、EDS、显微硬度分析以及盐雾试验等测试手段对渗铝层进行研究,发现通过机械能助渗铝得到的为富铝相渗层,渗层硬度是基体材料的两倍以上,且具有良好的耐腐蚀及...     

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.     

17-7PH沉淀硬化不锈钢电渣重熔过程洁净度的变化

采用35 t电弧炉-AOD脱碳-LF精炼-模铸工艺制备了17-7PH沉淀硬化不锈钢自耗电极,并通过气体保护电渣炉重熔得到了2 t重的电渣锭。利用ASPEX扫描电镜分析了电渣重熔前后17-7PH钢中夹杂物数量、尺寸、成分的变化规律,并采用SEM-EDS进一步观察夹杂物的形貌及组成。研究结果发现,电渣重熔后,O含量由6.6×10^-6降至5.7×10^-6,N含量由200×10^-6降至180×10^-6。重熔前后夹杂物的类型没有变化,重熔后总的夹杂物数量大幅减少,特别是大颗粒夹杂物的数量明显减少、尺寸减小。电渣锭中总的夹杂物以AlN夹杂物为主,其尺寸较大、数量最多。为了提高17-7PH钢电渣锭的洁净度,应尽可能减少自耗电极中的N含量,以减少电渣重熔过程AlN夹杂物的生成量。     

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.     

调整处理对0Cr17Ni4Cu4Nb不锈钢组织与力学性能的影响

实验室研究了调整处理工艺对0cr17Ni4Cu4Nb不锈钢组织与力学性能的影响,通过力学性能测试和金相显微组织观察,结果表明：随调整处理温度的提高,强度逐渐增加,塑性、韧性逐渐下降;816℃整处理后,随时效温度的提高,强度逐渐下降,塑性、韧性逐渐增加;在相同的时效温度下,与固溶态相比,调整处理后的强度显著较低但塑性、韧性较高。