AZ61Mg alloy was multi directionally forged(MDFed) during decreasing temperature condition from 643 K to 483 K at a true strain rate of 3×10-3 s-1 up to cumulative strain of∑△ε=4.0 at maximum.A pass strain of...AZ61Mg alloy was multi directionally forged(MDFed) during decreasing temperature condition from 643 K to 483 K at a true strain rate of 3×10-3 s-1 up to cumulative strain of∑△ε=4.0 at maximum.A pass strain of△ε=0.8 was employed.While average grain size decreased gradually with increasing cumulative strain,the evolution of fine-grained structure strongly depended on the MDF temperature.Under the condition where the temperature was higher than the most adequate one,grain coarsening partially took place during MDF.In contrast,at lower temperature,inhomogeneous microstructure composed of the initial coarse and newly appeared fine grains was evolved.After straining over∑△ε=3.2(i.e.,over 4 passes of MDF) ,equiaxed ultrafine grains(UFGs) having average size of about and lower than 1μm were uniformly evolved.While the MDFed alloy to∑△ε=4.0 possessed relatively high hardness of HV 99,and it accepted further about 20%cold rolling almost without cracking.Because of the superior formability of the UFGed AZ61Mg alloy,the hardness was further easily raised to HV 120 by following cold rolling.展开更多
This study investigated the effects of direct aging(DA),solution treatment(ST),and ST followed by DA(T6)on the microstructural,mechanical,and corrosion properties of direct powder forged Al–10 Si–0.3 Mg alloy specim...This study investigated the effects of direct aging(DA),solution treatment(ST),and ST followed by DA(T6)on the microstructural,mechanical,and corrosion properties of direct powder forged Al–10 Si–0.3 Mg alloy specimens.Microstructural analyses conducted using optical microscopy,scanning electron microscopy,and electron backscatter diffraction revealed that among DA specimens,direct aging at 200℃(DA-2)exhibited significantly enhanced silicon(Si)particle distribution uniformity and minimal interparticle boundaries owing to increased diffusion bonding;ST specimens exhibited partial Si dissolution,higher porosity,and retained the interparticle boundaries;and T6 specimens exhibited improved microstructural uniformity and enhanced Si precipitation.Furthermore,mechanical property evaluations indicated that T6 treatment comprising ST at 500℃for 180 min followed by DA at 200℃for 360 min resulted in the highest tensile strength(207.15 MPa)and elongation(5.02%),followed closely by DA at 200℃for 360 min(203.13 MPa and4.39%).These improvements were attributed to the lower residual stress,higher diffusion distances,and well-dispersed Si particles induced by DA-2 treatment.Corrosion analyses conducted using cyclic polarization and impedance spectroscopy indicated varied electrochemical responses,with DA-2 resulting in the lowest corrosion current and highest impedance,and ST resulting in the lowest corrosion resistance.Overall,DA at 200℃for 360 min was the most effective heat treatment,offering the optimal balance between mechanical and corrosion-resistance properties.展开更多
基金support given by the Light Metals Educational Foundation,Japan,and Ministry of Education,Culture,Sports and Technology,Japan,with Grant No.20560647
文摘AZ61Mg alloy was multi directionally forged(MDFed) during decreasing temperature condition from 643 K to 483 K at a true strain rate of 3×10-3 s-1 up to cumulative strain of∑△ε=4.0 at maximum.A pass strain of△ε=0.8 was employed.While average grain size decreased gradually with increasing cumulative strain,the evolution of fine-grained structure strongly depended on the MDF temperature.Under the condition where the temperature was higher than the most adequate one,grain coarsening partially took place during MDF.In contrast,at lower temperature,inhomogeneous microstructure composed of the initial coarse and newly appeared fine grains was evolved.After straining over∑△ε=3.2(i.e.,over 4 passes of MDF) ,equiaxed ultrafine grains(UFGs) having average size of about and lower than 1μm were uniformly evolved.While the MDFed alloy to∑△ε=4.0 possessed relatively high hardness of HV 99,and it accepted further about 20%cold rolling almost without cracking.Because of the superior formability of the UFGed AZ61Mg alloy,the hardness was further easily raised to HV 120 by following cold rolling.
基金financially supported by an initiation grant project:IITK/MET/2022094,Indian Institute of Technology Kanpur,India,and SERB(Grant No:EEQ/2020/000306).
文摘This study investigated the effects of direct aging(DA),solution treatment(ST),and ST followed by DA(T6)on the microstructural,mechanical,and corrosion properties of direct powder forged Al–10 Si–0.3 Mg alloy specimens.Microstructural analyses conducted using optical microscopy,scanning electron microscopy,and electron backscatter diffraction revealed that among DA specimens,direct aging at 200℃(DA-2)exhibited significantly enhanced silicon(Si)particle distribution uniformity and minimal interparticle boundaries owing to increased diffusion bonding;ST specimens exhibited partial Si dissolution,higher porosity,and retained the interparticle boundaries;and T6 specimens exhibited improved microstructural uniformity and enhanced Si precipitation.Furthermore,mechanical property evaluations indicated that T6 treatment comprising ST at 500℃for 180 min followed by DA at 200℃for 360 min resulted in the highest tensile strength(207.15 MPa)and elongation(5.02%),followed closely by DA at 200℃for 360 min(203.13 MPa and4.39%).These improvements were attributed to the lower residual stress,higher diffusion distances,and well-dispersed Si particles induced by DA-2 treatment.Corrosion analyses conducted using cyclic polarization and impedance spectroscopy indicated varied electrochemical responses,with DA-2 resulting in the lowest corrosion current and highest impedance,and ST resulting in the lowest corrosion resistance.Overall,DA at 200℃for 360 min was the most effective heat treatment,offering the optimal balance between mechanical and corrosion-resistance properties.
