Describes the weldability aspects of structural materials used in a wide variety of engineering structures, including steels, stainless steels, Ni-base alloys, and Al-base alloys Welding Metallurgy ...and Weldability describes weld failure mechanisms associated with either fabrication or service, and failure mechanisms related to microstructure of the weldment. Weldability issues are divided into fabrication and service related failures; early chapters address hot cracking, warm (solid-state) cracking, and cold cracking that occur during initial fabrication, or repair. Guidance on failure analysis is also provided, along with examples of SEM fractography that will aid in determining failure mechanisms. Welding Metallurgy and Weldability examines a number of weldability testing techniques that can be used to quantify susceptibility to various forms of weld cracking. Describes the mechanisms of weldability along with methods to improve weldability Includes an introduction to weldability testing and techniques, including strain-to-fracture and Varestraint tests Chapters are illustrated with practical examples based on 30 plus years of experience in the field Illustrating the weldability aspects of structural materials used in a wide variety of engineering structures, Welding Metallurgy and Weldability provides engineers and students with the information needed to understand the basic concepts of welding metallurgy and to interpret the failures in welded components.
The transverse-motion weldability (TMW) test, in which the lower sheet in lap welding is moved at a constant speed V in the transverse direction of welding to induce solidification cracking, was ...applied to Ni-base alloys. Alloys 600, 625, 718 and 800 were used as example materials for demonstration. The relative susceptibility ranking of the alloys was similar to those reported. A similar ranking was calculated based on |dT/d(f
S
)
1/2
| near (f
S
)
1/2
= 1 (T: temperature; f
S
: fraction solid). Based on the transverse micrograph of the weld and V, the critical local strain rate near the crack was estimated. It was significantly higher for 718 than 800, consistent with the significantly lower susceptibility of 718 shown by the TMW test.
•Biobased epoxy vitrimer was synthesized from epoxidized soybean oil.•The mechanical property of the epoxy vitrimer can be tuned by its crosslink density.•The epoxy vitrimer showed excellent ...reprocessability and weldability.
Biobased polymers prepared from vegetable oils such as epoxidized soybean oil (ESO) cannot be reprocessed or recycled due to the permanent crosslink structure. Herein, we report ESO derived vitrimers (ESOVs) synthesized by catalyst-free curing of ESO with 4, 4′-dithiodiphenylamine (APD) as a curing agent. The crosslink density controlled by curing time affect the mechanical properties of ESOV strongly. The tensile strength increased and elongation at break decreased gradually with increasing crosslink density of ESOV. The dynamic disulfide linkages of APD imparted the ESOV with excellent reprocessability and weldability via network topology rearrangement as a result of exchange reaction of disulfide bonds. The mechanical properties, gel fraction and chemical structure of ESOV almost remained unchanged after repeatedly cutting and compression molding for several times. The mechanical properties of ESOV were also recovered completely when two broken parts of ESOV were welded together. This study provides a facile and promising strategy to design novel functional materials from sustainable vegetable oils.
The paper presents the application of MAG welding to TMCP steels (thermo-mechanically controlled processed) grade S960MC and 3 mm thick. In the analyzed joints, the research focused on their ...mechanical properties and changes in the heat-affected zone (HAZ) that occur in this type of steels. The hardness and tensile strength tests carried out showed a significant decrease in the properties of the joint compared to the declared values of the base material and the filler material used in the tests. In the case of hardness, it was a decrease of 34% in HAZ and by 15-21% in relation to the strength limit. Changes in HAZ properties of a joint correlate with changes in its structure.
In this study the cold cracking (CC) susceptibility of naval grade high strength steel (HSS) welds developed using flux core wires of different yield strength levels was analyzed for lightweight ...shipbuilding structures. The steel plates of the PCE500 TM grade were welded in T-joint configuration using automatic flux core arc welding under the shielding gas. The CC susceptibility of weld metals was evaluated using Tekken weldability test. The microstructure of weld metal and the hardness of welded joint were analyzed using optical microscope and Vickers microhardness tester, respectively. Software package Sysweld was used for finite element simulation of CC susceptibility of weld metals. Results showed that the probability of CC increases with increase in the strength of filler wires, especially under conditions of limited welding deformations and exposure to low temperatures. The maximum resistance to the formation of cold cracks (CCs) in microstructure of the weld metal is observed in the presence acicular ferrite of at least 60%. To assess the structural strength of T-joint with soft welds, a calculation method has been developed, which allows ranking various structural and technological solutions of the T-joint from the condition of resistance to various types of fracture. Numerical calculation showed that the margin for brittle fracture at 11–23% and the gain in fatigue durability at 40% for welded joint with soft weld greater than for a welded joint with an equally strong weld. The use of low strength filler wires for welding thick plates of HSSs can successfully resolve the problem of CCs and ensure structural strength of joints.
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•A novel curing agent (TA) bearing imine backbones was synthesized conveniently.•Epoxy vitrimers based on imine bond were fabricated by curing DGEBF with TA.•Dynamic and high ...mechanical property of the vitrimer were simultaneously achieved.•The vitrimer exhibited high water-resistance due to the network’s hydrophobicity.
Vitrimers with covalent adaptable networks usually show low mechanical properties and water resistivity. Here, we report an epoxy vitrimer which possesses not only high weldability, malleability and programmability, but also outstanding mechanical properties and water insensitivity. Such epoxy vitrimer is fabricated by crosslinking diglycidyl ether of bisphenol F (DGEBF) with a novel curing agent bearing imine backbones and amino terminals. The curing agent is synthesized by a one-pot reaction between 3-aminobenzylamine and terephthalaldehyde by taking advantage of the different reactivity of the aromatic amine and aliphatic amine. The dynamic imine bonds of the curing agent enable malleability, shape reconfiguration and programming of the epoxy vitrimer, while the aromatic structure of the curing agent imparts the epoxy vitrimer with high tensile strength, Young modulus and thermal stability. Moreover, the epoxy vitrimer is highly water-resistant due to the hydrophobicity and high crosslinking density of the network. Such a combination of comprehensive properties and convenient fabrication approach makes the epoxy vitrimer hold great promise to serve as structural materials in diverse applications.
•It is a practical guidance for application of laser welding of AHSSs.•Both the similar and dissimilar joints of TWIP steel showed poor weldability.•Shrinkage porosities and segregation in fusion ...zone were the main weld defects.•Solidification cracks leaded to the brittle fracture of corresponding joints.
Twinning induced plasticity steel (TWIP980) was fiber laser welded with dual phase steel (DP980), hot stamping boron steel (B1500HS), and quenching & partitioning steel (QP980). The microstructures, segregation behaviors and mechanical properties of similar or dissimilar joints were characterized. All the joints exhibited poor weldability because of the segregation of Mn and C in fusion zone, especially in dissimilar joints of TWIP980/DP980, TWIP980/B1500HS, and TWIP980/QP980. The microstructure in fusion zone of TWIP980/TWIP980 and TWIP980/B1500HS joints consisted of austenite, while fully martensite was found in TWIP980/DP980 and TWIP980/QP980 fusion zone. The solidification cracks in fusion zone of TWIP980/DP980 and TWIP980/QP980 joints embrittled corresponding joints, which contributed to the lower tensile strength and elongation.
•Realized data-driven cyber-physical system for RSW certification with integrated analytics and optimization capabilities.•Integrating data from analytics lifecycle phases - data collection operation ...to predictive analytics to design visualization.•The framework is based on conceptualization of layers of cyber-physical system and incorporates design and machine changes.•Closed-loop machine parameter optimization implemented considering the target product design.•Case study based on a real industrial weldability certification to illustrate the application of the envisioned framework.
A cyber-physical system is one of the integral parts of the development endeavor of the smart manufacturing domain and the Industry 4.0 wave. With the advances in data analytics, smart manufacturing is gradually transforming the global manufacturing landscape. In the Resistance Spot Welding (RSW) domain, the focus has been more on the physical systems, compared to the virtual systems. The cyber-physical system facilitates the integrated analysis of the design and manufacturing processes by converging the physical and virtual stages to improve product quality in real-time. However, a cyber-physical system integrated RSW weldability certification is still an unmet need. This research is to realize a real-time data-driven cyber-physical system framework with integrated analytics and parameter optimization capabilities for connected RSW weldability certification. The framework is based on the conceptualization of the layers of the cyber-physical system and can incorporate the design and machine changes. It integrates data from the analytics lifecycle phases, starting from the data collection operation, to the predictive analytics operation, and to the visualization of the design. This integrated framework aims to support decision-makers to understand product design and its manufacturing implications. In addition to data analytics, the proposed framework implements a closed-loop machine parameter optimization considering the target product design. The framework visualizes the target product assembly with predicted response parameters along with displaying the process parameters and material design parameters simultaneously. This layer should help the designers in their decision-making process and the engineers to gain knowledge about the manufacturing processes. A case study on the basis of a real industrial case and data is presented in detail to illustrate the application of the envisioned cyber-physical systems framework.
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•Unique graphene ribbon and Ni wire lead robust electron and ion transport.•Ultrahigh length capacitance of 73.8 mF·cm−1.•Excellent weldability of our devices.
Carbon-based fiber ...supercapacitors hold great potential in portable electronics. However, those fiber-based electrodes often suffer from low length capacitance and poor rate performance due to low electrical conductivity and sluggish ion diffusion kinetics. And the poor weldability hinders the design of complex circuits. Herein, we report a simple strategy to prepare weldable and flexible graphene ribbon@Ni fiber (GR-Ni-5) with fast ion/electron transfer capabilities for fiber-shaped supercapacitors via the immersion-drying process and followed by thermal treatment. As a result, the GR-Ni-5 exhibits an ultrahigh length capacitance of 73.8 mF·cm−1 at 2 mV·s−1, remarkable rate performance (26.8 mF·cm−1, 200 mV·s−1), and ultrahigh capacitance retention of 80% with the length of the electrode from 1.0 to 10.0 cm. Moreover, the assembled all-solid-state symmetric supercapacitor using GR-Ni-5 fibers as the electrodes and polyvinyl alcohol (PVA)/KOH gel as electrolyte can deliver remarkable electrochemistry properties, as well as good flexibility, and remarkable weldability which are beneficial for miniaturization and application.
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