Additive manufacturing of metallic components – Process, structure and properties

https://findresearcher.sdu.dk:8443/ws/files/116118561/reverse_logistics.pdf

Reverse logistics and closed-loop supply chain: A comprehensive review to explore the future

Welding Metallurgy of

Surface composites by friction stir processing: A review

Revisiting fundamental welding concepts to improve additive manufacturing: From theory to practice

Formation and influence mechanism of keyhole-induced porosity in deep-penetration laser welding based on 3D transient modeling

Numerical simulation on interaction between TIG welding arc and weld pool

Study on welding process and prosperities of AA5754 Al-alloy welded by double pulsed gas metal arc welding

In order to study arc profile variation process with double-pulsed gas metal arc welding of aluminum alloy, a synchronous acquisition system and an analysis system have been established to acquire and analyze electrical signals and instantaneous images of arc profile. The results show that in double-pulse mode, the arc profile is matched with high-frequency pulse and thermal pulse. The droplet transfer mode always accompanies with high-frequency pulse cycle “one drop per pulse.” The arc profile variation and droplet transfer in thermal base are lower than that in thermal peak. The serial-type arc is easier to occur in thermal base stage. High current density distribution at the top and bottom of traveling droplet leads to dazzling region. The variation of wire extension is influenced by thermal pulse frequency. The variance of arc size in thermal base is higher than in thermal peak, which leads arc force to vary with thermal pulse frequency. The variation of the droplet transfer and arc force in double pulse can improve the weld pool mobility.

Arc profile characteristics of Al alloy in double-pulsed GMAW

In the present work, the creep behavior and microstructure before and after creep test of the dissimilar modified 9Cr–1Mo steels welded joint were investigated in detail. Firstly, creep tests were carried out at different stress values/levels under the temperature of 538 °C and 500 °C, and then the power law equation of steady-state stage were achieved based on the results. The microstructure of welded joint were characterized in detail, the tempered martensite structure is the typical microstructure of whole welded joint, and the δ-ferrite phase is observed in heated affect zone (HAZ) and the base metal without Co and B elements (BM1). A soft zone called over-tempering zone (OTZ) occurred in both HAZs, which was determined by micro-hardness measurement, due to the lower dislocation density and coarsened M 23 C 6 carbides of this zone. The fracture location is in OTZ adjacent to BM1 side determined by microstructure, micro-hardness and geometric calculation. Lots of voids are observed along the triple grain boundaries associated with large second phase particles after creep rupture. The stress concentration caused by the coarsened carbides at the triple boundaries and softening matrix are considered as the main factor of creep voids occurring in the OTZ of welded joint.

Xinhua Tang

Papers

Formation and influence mechanism of keyhole-induced porosity in deep-penetration laser welding based on 3D transient modeling

Numerical simulation on interaction between TIG welding arc and weld pool

Study on welding process and prosperities of AA5754 Al-alloy welded by double pulsed gas metal arc welding

Arc profile characteristics of Al alloy in double-pulsed GMAW

Creep behavior and microstructure evaluation of welded joint in dissimilar modified 9Cr–1Mo steels