Abstract: By reheating the semi-solid microstructure with spheroidal solid particles distributed uniformly in the liquid phase can be obtained. The reheating conditions of the semi-solid billet of ZL101 alloy produced by re-melting heat treatment method were studied. The rational reheating route including optimal holding time was obtained through reheating experiments using a high frequency heater with power of 20kW and frequency of 30kHz. The results show that it is necessary to divide the whole reheating process into several heating stages with different heating rates in order to obtain satisfactory semi-solid structure before final forming. Finally, the structure evolution during reheating process was discussed.
上海交通大学模具CAD国家工程研究中心,上海交通大学模具CAD国家工程研究中心,Osaka University,Yamada oka 2-1,Suita,Osaka,Japan ,Osaka University,Yamada oka 2-1,Suita,Osaka,Japan ,Osaka University,Yamada oka 2-1,Suita,Osaka,Japan ,Osaka University,Yamada oka 2-1,Suita,Osaka,Japan 上海200030 ,上海200030
By reheating the semi-solid microstructure with spheroidal solid particles distributed uniformly in the liquid phase can be obtained. The reheating conditions of the semi-solid billet of ZL101 alloy produced by re-melting heat treatment method were studied. The rational reheating route including optimal holding time was obtained through reheating experiments using a high frequency heater with power of 20 kW and frequency of 30 kHz. The results show that it is necessary to pide the whole reheating process into several heating stages with different heating rates in order to obtain satisfactory semi-solid structure before final forming. Finally, the structure evolution during reheating process was discussed.
表2 半固态组织初晶相尺寸及形状的计算结果 Table 2 Calculated dimensions andshape of primary phase in semi-solid state
Holding time/s
3 steps heating
4 steps heating
Roundness
Diameter/μm
Roundness
Diameter/μm
60
1.37±0.33
147.37±62.09
1.32±0.17
148.60±58.18
90
1.28±0.24
118.32±50.04
1.31±0.27
134.86±54.10
120
1.44±0.27
133.14±47.53
1.16±0.08
150.33±41.59
150
1.42±0.48
130.29±57.92
1.26±0.18
136.68±31.76
300
1.48±0.39
179.74±86.01
1.33±0.23
143.18±36.67
420
1.24±0.21
188.72±60.50
1.36±0.31
173.92±53.78
图3 三步二次加热获得的半固态组织 Fig.3 Semi-solid microstructures after three steps reheating for different durations (a)—60 s; (b)—90 s; (c)—120 s; (d)—150 s; (e)—300 s; (f)—420 s
图4 四步二次加热获得的半固态组织 Fig.4 Semi-solid microstructures after four steps reheating for different durations (a)—60 s; (b)—90 s; (c)—120 s; (d)—150 s; (e)—300 s; (f)—420 s
