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Author: search.filters.author.Kanlayasiri, KannachaiSubject: search.filters.subject.Microstructure

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    Influence of electrode shape and material on shear force and microstructure of resistance spot welded AZ80 magnesium alloy
    (2025-01-05)
    Sangrayub, Phoometh
    ;
    Kanlayasiri, Kannachai
    Resistance spot welding of AZ80 magnesium alloy is challenging owing to limited understanding of how electrode design and welding parameters interact to influence joint microstructure and strength. This study investigates the effects of electrode shape and material on the shear force and microstructure of resistance spot-welded AZ80 magnesium alloy. Three electrode shapes (A, R, and P) and two electrode materials (ZrCrCu and Al<inf>2</inf>O<inf>3</inf>Cu) were analyzed at welding currents of 13 kA and 17 kA. Nugget size and failure modes were also examined. The results demonstrate that electrode shape and material significantly affect welding heat, nugget size, and joint strength. The fusion zone (FZ) area increased due to the combined effects of welding current, electrode shape, and material. Higher welding heat modified the FZ boundary microstructure, transitioning from cellular morphologies to columnar dendrites, and eventually to equiaxed dendrites, thereby enhancing joint strength. The highest shear force was observed with an R-shaped ZrCrCu electrode at a welding current of 17 kA. However, excessive welding heat reduced the FZ area due to molten metal expulsion. It also promoted the growth of the brittle β-Mg<inf>17</inf>Al<inf>12</inf> phase in the coarse grain heat-affected zone (CGHAZ), shifting the fracture pattern from nugget pull-out to through-thickness in the base metal and decreasing joint strength. This study concludes that selecting appropriate electrodes can mitigate β-Mg<inf>17</inf>Al<inf>12</inf> phase growth in the CGHAZ, highlighting the importance of optimizing welding parameters for improved joint quality in AZ80 magnesium alloy welding.
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    Brazing of Porous Copper Foam with Copper Sheet Using CuNiSnP Amorphous Filler Metal
    (2021-01-01)
    Mookam, Niwat
    ;
    Jattakul, Prajak
    ;
    Rakphet, Tipsuda
    ;
    Kanlayasiri, Kannachai
    This research studies effects of the brazing time on interfacial microstructure of brazed joint between the porous copper foam (PCF) and Cu substrate using CuNiSnP amorphous filler metal. To examine the interfacial microstructure and its properties, an assessment of PCF/CuNiSnP/Cu brazed joints was conducted after electric furnace brazing under hydrogen (H2) atmosphere. The results showed that the interfacial microstructure was thick for short brazing time specimens and thin for prolonged brazing time specimens. The interfacial microstructures consisted of Cu-rich solid solution, (Cu, Ni)3P, and Cu3P as a eutectic structure discovered in the brazing region at different brazing times of 5, 10, and 20 min. Only the Cu-rich solid solution and (Cu, Ni)3P were found in the specimen with brazing time of 30 min. indicating that different brazing times affected interfacial microstructures and therefore reliability of the brazed joints.
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    Effect of soldering condition on formation of intermetallic phases developed between Sn-0.3Ag-0.7Cu low-silver lead-free solder and Cu substrate
    (2011-05-26)
    Mookam, Niwat
    ;
    Kanlayasiri, Kannachai
    In this paper, effect of soldering time and temperature on formation of intermetallic compounds developed between Sn-0.3Ag-0.7Cu lead-free solder and copper substrate was investigated. Dip soldering was performed at 250, 270, and 290 °C with soldering time of 5, 10, 15, and 20 s. Either ε-Cu <inf>3</inf>Sn or η-Cu<inf>6</inf>Sn<inf>5</inf> intermetallic phase was found at the interface between the solder and the substrate depending on the soldering condition, i.e., soldering time and soldering temperature. ε-Cu<inf>3</inf>Sn was found only when the substrate was soldered at 250 °C for 5 and 10 s. At other soldering conditions, only η-Cu <inf>6</inf>Sn<inf>5</inf> was found at the interfacial zone. Crystal structure of ε-Cu<inf>3</inf>Sn intermetallic phase was orthorhombic, and it was hexagonal structure for η-Cu<inf>6</inf>Sn<inf>5</inf>. Transformation of the intermetallic phases was also discussed. © 2011 Elsevier B.V. All rights reserved.
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    Influence of thermal aging on microhardness and microstructure of Sn-0.3Ag-0.7Cu-xIn lead-free solders
    (2010-08-31)
    Kanlayasiri, Kannachai
    ;
    Ariga, Tadashi
    Sn-0.3Ag-0.7Cu is a low-silver lead-free solder, and provides a thinner brittle Ag<inf>3</inf>Sn intermetallic layer during soldering process. In this paper, effects of thermal aging on microhardness, and microstructure of Sn-0.3Ag-0.7Cu-xIn lead-free solders were investigated. Indium was added to lower the melting temperature, and varied from 0.0 to 3.0 wt%. The solders were thermally aged at 100 °C for 1, 10, 100, and 1000 h. Results showed that microhardness of the solders decreases as the aging time increases, and average grain size of the microstructure is larger with the increase of the aging time. It was also found that the higher In content in the solder provides the greater decreasing rate of its microhardness. © 2010 Elsevier B.V. All rights reserved.
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    Influence of indium addition on characteristics of Sn-0.3Ag-0.7Cu solder alloy
    (2009-10-19)
    Kanlayasiri, Kannachai
    ;
    Mongkolwongrojn, Mongkol
    ;
    Ariga, Tadashi
    Effects of indium (In) addition on solidus and liquidus temperatures, wetting time, wetting force, tensile strength, and microhardness of Sn-0.3Ag-0.7Cu lead-free solder alloy were investigated in this paper. Indium was added and varied from 0 to 3 wt%. It is found that solidus and liquidus temperatures of the solder alloy are lowered as the In content is increased. However, In also increases the melting range between solidus and liquidus temperatures. Wetting time of the solder alloy is reduced by the addition of In while the wetting force is increased with the increase of In content. With the addition of In, the Sn-rich phase is smaller in size, and the intermetallic compounds are more uniformly distributed. As a result, tensile strength and microhardness of Sn-0.3Ag-0.7Cu are increased when In is added into the solder alloy. © 2009 Elsevier B.V. All rights reserved.