Study on Microstructure and Property of the SHS Welding Joint

2012 ◽  
Vol 590 ◽  
pp. 51-55
Author(s):  
Hui Yang ◽  
Guo Dong Zhang ◽  
Yuan Mei Fei
Keyword(s):  
Base Metal ◽  
Large Scale ◽  
Welded Joint ◽  
Automatic Measurement ◽  
Weld Interface ◽  
Hardness Tester ◽  
Metallurgical Bonding ◽  
Structure Morphology ◽  
Digital Microscope ◽  
Welding Metal

With the self-designed welding powder formula,this experiment employed the SHS reaction to weld the base metal,which was steel Q235 here,then respectively used Olympus large-scale horizontal digital microscope to analyze the structure morphology of the welding seam's different regions,JEOL SEM to point-analyze and line-analyze elements' distribution near the the weld interface and HV-1000 CCD automatic measurement microscopic vickers hardness tester to measure the microhardness of the pure copper's welding seam.The experiment's result shows the hardness of different part of the welded joint varies largely,and that the join of alloy elements can increase the microhardness of the welding metal,and that the welding metal and base metal interdiffuse,grow and mix remarkably near the fusion line,realizing wonderful metallurgical bonding.

Research on Microstructures and Mechanical Properties of Fiber Laser Welding of A7N01 Al-Alloy

2017 ◽  
Vol 734 ◽  
pp. 310-318 ◽  
Author(s):  
Yi Shuai Jiang ◽  
Shang Lei Yang ◽  
Yan Wang ◽  
Zhi Hua Yang
Keyword(s):  
Mechanical Properties ◽  
Fiber Laser ◽  
Base Metal ◽  
Welded Joint ◽  
Weld Interface ◽  
Al Alloy ◽  
Fiber Laser Welding ◽  
Welding Joint ◽  
Microstructures And Mechanical Properties ◽  
Welding Metal

A7N01 aluminum alloy with the thickness of 10mm is welded using fiber laser with filler wire, the microstructures and mechanical properties of the welding joints are observed and analyzed by microhardness and tensile testers, SEM. The results show that the crystalline morphology of the welding metal is equiaxial as-cast. the columnar crystals exist in the fusion zone next to the weld interface. A softening zone with the width of 1.6 mm is formed in the heat affected zone. Micro-hardness of the welding joint distributes uniformly, the highest is in base metal which is 110 HV and the lowest is in the welding joint which is 73 HV. The tensile strength of the welded joint is 281 MPa, the strength coefficient reached 70.6%. the fatigue strengths of the laser welded joint and the base metal are investigated. The results show that the conditional fatigue strength (107) of the laser welded joint can reach up to 63.6% of that of the base metal. there are fatigue striations generated during the steady-state region.

Joint Strength and its Improvement of Friction Welded Joint Between Ductile Cast Iron and 5052 Al Alloy

2020 ◽  
Author(s):  
Masaaki Kimura ◽  
Akira Yoneda ◽  
Masahiro Kusaka ◽  
Koichi Kaizu ◽  
Kazuhiro Hayashida ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Cast Iron ◽  
Base Metal ◽  
Joint Strength ◽  
Welded Joint ◽  
Weld Interface ◽  
Ductile Cast Iron ◽  
Al Alloy ◽  
High Tensile Strength ◽  
Graphite Particles

Abstract To obtain dissimilar joint for easily making multi-material structures, the characteristics of friction welded joint between ductile cast iron (FCD400) and 5052 Al alloy (A5052) was investigated. The relatively high tensile strength of joint was obtained when that was made with a friction speed of 27.5 s−1, a friction pressure of 20 MPa, a friction time of 1.5 s, and a forge pressure of 270 MPa, respectively. However, this joint had approximately 77% in the tensile strength of the A5052 base metal and that was fractured at the weld interface. Although the weld interface had no intermetallic compound layer, the fractured surface at the A5052 side had some graphite particles that were supplied from the FCD400 side. To improve the joint strength, the graphite particles were reduced from the weld faying surface at the FCD400 side by decarburization treatment. The joint had approximately 96% in the tensile strength of the A5052 base metal and that was fractured between the A5052 side and the weld interface. The joint with high tensile strength as well as the possibility improving the fractured point of that were obtained when those were made with opportune friction welding condition and no graphite particles at the weld faying surface of the FCD400 side.

scholarly journals Selective hydroboration of unsaturated bonds by an easily accessible heterotopic cobalt catalyst

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Chuhan Li ◽  
Shuo Song ◽  
Yuling Li ◽  
Chang Xu ◽  
Qiquan Luo ◽  
...  
Keyword(s):  
Base Metal ◽  
Large Scale ◽  
Metal Cluster ◽  
Active Species ◽  
Cobalt Catalysts ◽  
Metal Salts ◽  
One Pot ◽  
Practical Utilization ◽  
Earth Abundant

AbstractHomogeneous earth-abundant metal catalysis based on well-defined molecular complexes has achieved great advance in synthetic methodologies. However, sophisticated ligand, hazardous activator and multistep synthesis starting from base metal salts are generally required for the generation of active molecular catalysts, which may hinder their broad application in large scale organic synthesis. Therefore, the development of metal cluster catalysts formed in situ from simple earth-abundant metal salts is of importance for the practical utilization of base metal resource, yet it is still in its infancy. Herein, a mixture of catalytic amounts of cobalt (II) iodide and potassium tert-butoxide is discovered to be highly active for selective hydroboration of vinylarenes and dihydroboration of nitriles, affording a good yield of diversified hydroboration products that without isolation can readily undergo further one pot transformations. It should be highlighted that the alkoxide-pinacolborane combination acts as an efficient activation strategy to activate cobalt (II) iodide for the generation of metastable heterotopic cobalt catalysts in situ, which is proposed to be catalytically active species.

Hardness Evolution and High Temperature Mechanical Properties of Laser Welded DP980 Steel Joints

2018 ◽  
Vol 37 (6) ◽  
pp. 587-595
Author(s):  
Zhandong Wan ◽  
Wei Guo ◽  
Qiang Jia ◽  
Lang Xu ◽  
Peng Peng
Keyword(s):  
Yield Strength ◽  
Energy Absorption ◽  
Base Metal ◽  
Welded Joint ◽  
Dynamic Strain ◽  
Minor Effect ◽  
Fiber Laser Welding ◽  
Fine Grained ◽  
High Temperature Mechanical Properties ◽  
A Minor

AbstractDP980 steels were joined using fiber laser welding. The welded joint was characterized in terms of hardness distribution and tensile behavior at room temperature, 150 ℃, and 300 ℃, respectively. The fine-grained martensite in supercritical heat affected zone (HAZ) resulted in the highest hardness (428 Hv), while the tempered martensite contributed to the hardness decreasing (‒31 Hv). Both the ultimate tensile strength and yield strength of the base metal and welded joint decreased at 150 ℃, and then increased at 300 ℃ due to dynamic strain aging (DSA). The welded joint exhibited slightly higher yield strength and lower elongation at all the test temperatures compared to base metal due to the hardened fusion zone. The energy absorption reduced slightly with increasing temperature both for base metal and welded joint, and the weld posed a minor effect on the energy absorption. Deformation was one of the requirements for DSA effect. DSA enhanced the hardness of base metal (+78 Hv) and softened zone (+53 Hv). HAZ was not softened enough to become the weakest position during tensile test.

scholarly journals Corrosion of the Welded Aluminium Alloy in 0.5 M NaCl Solution. Part 2: Coating Protection

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2177 ◽  
Author(s):  
Andrey Gnedenkov ◽  
Sergey Sinebryukhov ◽  
Dmitry Mashtalyar ◽  
Igor Vyaliy ◽  
Vladimir Egorkin ◽  
...  
Keyword(s):  
Aluminium Alloy ◽  
Welded Joint ◽  
Electrochemical Impedance ◽  
Corrosion Behaviour ◽  
Weld Interface ◽  
Open Circuit ◽  
Al Alloy ◽  
Protective Properties ◽  
Coating Formation ◽  
Electrode Technique

The high electrochemical activity of the aircraft 1579 aluminium alloy with a welded joint and the necessity of the coating formation to protect this material against corrosion as well as to increase the stability of the weld interface in the corrosive medium has been previously established. In this work, two suggested methods of protective coating formation based on plasma electrolytic oxidation (PEO) in tartrate-fluoride electrolyte significantly increased the protective properties of the welded joint area of the 1579 Al alloy. The electrochemical properties of the formed surface layers have been investigated using SVET (scanning vibrating electrode technique) and SIET (scanning ion-selective electrode technique), EIS (electrochemical impedance spectroscopy), OCP (open circuit potential), and PDP (potentiodynamic polarization) in 0.5 M NaCl. The less expressed character of the local electrochemical processes on the welded 1579 Al alloy with the composite coating in comparison with the base PEO-layer has been established. Polymer-containing coatings obtained using superdispersed polytetrafluoroethylene (SPTFE) treatment are characterized by the best possible protective properties and prevent the material from corrosion destruction. Single SPTFE treatment enables one to increase PEO-layer protection by 5.5 times. The results of this study indicate that SVET and SIET are promising to characterize and to compare corrosion behaviour of coated and uncoated samples with a welded joint in chloride-containing media.

Recent Developments in Japanese Flaw Assessment Methods of WES 2805

2008 ◽  
Author(s):  
Yukito Hagihara ◽  
Masayoshi Kurihara ◽  
Hitoshi Yoshinari ◽  
Takashi Miyata
Keyword(s):  
Welded Joints ◽  
Large Scale ◽  
Welded Joint ◽  
Estimation Method ◽  
Assessment Methods ◽  
Crack Tip Opening Displacement ◽  
Opening Displacement ◽  
Design Curve ◽  
Load Carrying ◽  
Recent Developments

The standard for the method of assessment for flaws in the welded joints of WES 2805 was first published in 1976 and was revised in 1980 and 1997. A further revision has been carried out by the technical committee of FTS in the Japan Welding Engineering Society and the revision was completed in 2007. The standard of WES 2805 is based on a CTOD (crack tip opening displacement) design curve approach for brittle fracture, and is used for the assessment of the significance of flaws in a stress concentrated region, where large scale yielding takes place. Main topics for the recent developments for flaw assessment methods are described in this paper. These are the interaction criterion of multiple flaws, fatigue crack growth laws, determination of equivalent crack length and strain due to stress concentration, estimation method of the critical CTOD from Charpy energy and proposal of partial safety factors. In order to examine the effectiveness of the standard, extensive 2-D and 3-D FE analyses are performed for various welded joints such as a load-carrying fillet welded joint, a non-load-carrying fillet welded joint and a box welded joint. Some of them are introduced in this paper. Their analytical results indicate that the present CTOD design curve method gives a reasonable evaluation.

Creep Strength Evaluation of a New and a Used Grade 91 Welded Joints by Using a Miniature Specimen

2018 ◽  
Author(s):  
Takashi Ogata
Keyword(s):  
Weld Metal ◽  
Strain Rate ◽  
Creep Strain ◽  
Base Metal ◽  
Welded Joints ◽  
Welded Joint ◽  
Creep Damage ◽  
Creep Strain Rate ◽  
Standard Size ◽  
Grade 91

Grade 91 is widely used for steam pipes and tubes in high temperature boilers of ultra-super critical power plants in Japan. It was reported that creep damage may initiate at the fine grain region within the heat affected zone (HAZ) in welded joints prior to the base metal, so called “Type IV” damage, which causes steam leakage in existing power plants. Therefore, development of creep damage assessment methods is not only an important but also an urgent subject to maintain operation reliability. In order to evaluate creep damage of welded joints based on finite element analyses, creep deformation properties of a base metal, a weld metal and a HAZ have to be obtained from creep tests. However, it is difficult to cut a standard size creep specimen from the HAZ region. Only a miniature size specimen is available from the narrow HAZ region. Therefore, development of creep testing and evaluation technique for miniature size specimens is highly expected. In this study, a miniature tensile type solid bar specimen with 1mm diameter was machined from a base metal, a weld metal and a HAZ of a new and a used Grade 91 welded joints, and creep tests of these miniature specimens were conducted by using a special developed creep testing machine. It was found that creep deformation property is almost identical between the base metal and weld metal, and creep strain rate of the HAZ is much faster than that of these metals in the new welded joint. Relationships between stress and creep strain rates of the base metal and the HAZ in the used welded joint are within scatter bands of those in the new material. On the other hand, creep strain rate of the weld metal in the used welded joint became much faster than that in the new one. Then both the standard size and the miniature size cross weld specimens were machined from the new and the used welded joints and were tested under the same temperature and stress conditions. Rupture time of the miniature cross weld specimen is much shorter than that of the standard size cross weld specimen. The finite element creep analysis of the specimens indicates that higher triaxiality stress yields within the HAZ of the standard size specimen than that of the miniature specimen causing faster creep strain rate in the HAZ of the miniature cross weld specimen.

Experimental and Numerical Evaluation of Fracture Toughness on Electron Beam Welded Joint in Al6061-T6

2016 ◽  
Author(s):  
W. Rekik ◽  
O. Ancelet ◽  
C. Gardin ◽  
F. Hamon
Keyword(s):  
Electron Beam ◽  
Mechanical Behavior ◽  
Yield Stress ◽  
Base Metal ◽  
Heat Affected Zone ◽  
Welded Joint ◽  
Material Behavior ◽  
Failure Assessment ◽  
Tearing Resistance ◽  
Alloy 6061

In order to ensure the integrity of structures, failure assessment is required. In this context, the fracture behavior of an electron beam (EB) welded joint on thick plate of aluminum alloy 6061-T6 used for structural components of experimental nuclear reactors was investigated. In the particular case of welded structures, the tearing resistance is strongly dependent on the mismatch of the welded joint and the local behavior of each metallurgical zone. For a reliable analysis, the tensile mechanical behavior of each position of the welded joint was precisely determined by the use of a new measurement prototype. The toughness behavior under different configurations was then evaluated on CT specimens. From these experimental results a mechanical behavior contrast was highlighted. In fact, the fusion zone presents the lowest yield stress and a gradient is observed in the heat affected zone until the material behavior reaches of the base metal yield stress. On the contrary, the toughness of the welded zone is the highest and decreases strongly in the heat affected zone according to an exponential function until the base metal toughness is reached.

Sign in / Sign up

Export Citation Format

Share Document