Ti-6Al-4V alloy(Ti64)and SUS316 L stainless steel rods were dissimilarly friction welded.Especially focusing on the detailed observation of interface microstructural evolution during the friction welding(FW),the relat...Ti-6Al-4V alloy(Ti64)and SUS316 L stainless steel rods were dissimilarly friction welded.Especially focusing on the detailed observation of interface microstructural evolution during the friction welding(FW),the relationship between the processing conditions,weld interface microstructure,and mechanical properties of the obtained joints were systematically investigated to elucidate the principle for obtaining a high joint quality in the FW of Ti64 and SUS316L.A higher friction pressure produced a lower welding temperature in the FW,hence suppressing the thick intermetallic compound layer formation.However,hard and brittle Ti64/SUS316L mechanically mixed layers generally formed especially at the weld interface periphery due to the high temperature increasing rate,high rotation linear velocity and high outward flow velocity of the Ti64.These harmful layers tended to induce the cracks/voids formation at the weld interfaces hence deteriorating the joints’mechanical properties.The rotation speed reduction and liquid CO2 cooling during the entire processing decreased the temperature increasing rate,rotation linear velocity and outward flow velocity of the Ti64 at the weld interface periphery.Therefore,they suppressed the formation of the harmful mechanically mixed layers,facilitated the homogeneous and sound interface microstructure generation,and finally produced a high-quality dissimilar joint in the FW of Ti64 and SUS316L.展开更多
The Al alloy and carbon fiber reinforced polymer(CFRP)hybrid structures,incorporating the performance advantages of the two materials,have been attracting more attention in high-end manufacturing fields.In the current...The Al alloy and carbon fiber reinforced polymer(CFRP)hybrid structures,incorporating the performance advantages of the two materials,have been attracting more attention in high-end manufacturing fields.In the current investigation,the flat friction spot joining(FSJ)was employed in joining the AA6061-T6 alloy and CFRP sheets.The significance of temperature distribution in influencing joint quality was highlighted through analyzing interface microstructural features,weld defect formation as well as fractography.To understand the role of thermal energy generation and conduction in the process comprehensively,a 3D thermal-mechanical coupling finite element model was established.The interfacial temperature was characterized by an uneven distribution behavior due to the inhomogeneous heat distribution.The peak temperatures on the top surface and Al alloy to CFRP interface at 1500 rpm rotational speed with 0.1 mm/s plunging speed were 498℃and 489°C,respectively.The peak interface temperature was reduced to286℃at 250 rpm,which produced an extremely small melted area.Compared with the plunging speed,rotational speed was found to be the predominant parameter for determining the joint property,which could be optimized to simultaneously realize the avoidance of thermal decomposition of CFRP,the sufficient melting duration time,and the wide enough melted area.Simulated thermal histories and melted area profiles were in agreement with experimental ones.The findings could be utilized to provide some feasible guidance for process optimization of dissimilar FSJ of metals and composites.展开更多
基金the New Energy and Industrial Technology Development Organization(NEDO)under the“Innovation Structural Materials Project(Future Pioneering Projects)”JSPS KAKENHI Grant Numbers JP19H00826 and JP18K14027an ISIJ Research Promotion Grant。
文摘Ti-6Al-4V alloy(Ti64)and SUS316 L stainless steel rods were dissimilarly friction welded.Especially focusing on the detailed observation of interface microstructural evolution during the friction welding(FW),the relationship between the processing conditions,weld interface microstructure,and mechanical properties of the obtained joints were systematically investigated to elucidate the principle for obtaining a high joint quality in the FW of Ti64 and SUS316L.A higher friction pressure produced a lower welding temperature in the FW,hence suppressing the thick intermetallic compound layer formation.However,hard and brittle Ti64/SUS316L mechanically mixed layers generally formed especially at the weld interface periphery due to the high temperature increasing rate,high rotation linear velocity and high outward flow velocity of the Ti64.These harmful layers tended to induce the cracks/voids formation at the weld interfaces hence deteriorating the joints’mechanical properties.The rotation speed reduction and liquid CO2 cooling during the entire processing decreased the temperature increasing rate,rotation linear velocity and outward flow velocity of the Ti64 at the weld interface periphery.Therefore,they suppressed the formation of the harmful mechanically mixed layers,facilitated the homogeneous and sound interface microstructure generation,and finally produced a high-quality dissimilar joint in the FW of Ti64 and SUS316L.
基金financially supported by the New Energy and Industrial Technology Development Organization(NEDO)under the"Innovation Structural Materials Project(Future Pioneering Projects)"。
文摘The Al alloy and carbon fiber reinforced polymer(CFRP)hybrid structures,incorporating the performance advantages of the two materials,have been attracting more attention in high-end manufacturing fields.In the current investigation,the flat friction spot joining(FSJ)was employed in joining the AA6061-T6 alloy and CFRP sheets.The significance of temperature distribution in influencing joint quality was highlighted through analyzing interface microstructural features,weld defect formation as well as fractography.To understand the role of thermal energy generation and conduction in the process comprehensively,a 3D thermal-mechanical coupling finite element model was established.The interfacial temperature was characterized by an uneven distribution behavior due to the inhomogeneous heat distribution.The peak temperatures on the top surface and Al alloy to CFRP interface at 1500 rpm rotational speed with 0.1 mm/s plunging speed were 498℃and 489°C,respectively.The peak interface temperature was reduced to286℃at 250 rpm,which produced an extremely small melted area.Compared with the plunging speed,rotational speed was found to be the predominant parameter for determining the joint property,which could be optimized to simultaneously realize the avoidance of thermal decomposition of CFRP,the sufficient melting duration time,and the wide enough melted area.Simulated thermal histories and melted area profiles were in agreement with experimental ones.The findings could be utilized to provide some feasible guidance for process optimization of dissimilar FSJ of metals and composites.
