Prediction Of Hot Tearing Tendency For Multicomponent Aluminum Alloys

Hot tearing is one of the most common and the most serious defects that occurs during casting of aluminum alloys.It is very important in practice to predict the hot tearing tendency for multicomponent aluminum alloys.Based on the CSC model proposed by Clyne and Davies,phase diagram calculations coupled with solidification simulation was used to provide detailed information about thermal physical properties of aluminum alloys.A software to predict the hot tearing tendency for multicomponent aluminum alloys was developed proprietarily in our group.Experimental value of HTS is introduced to get the maximum cracking length to modify the CSC for multicomponent system.Binary,ternary and multicomponent aluminum alloys are predicted by this software using Single Point Module and Area Module,what's more,our prediction results are consistent with the experimental data from literature.The main results are summarized as follows.(1)Using PanEngine API and MFC,we custom-developed the prediction software which is convenient for user to operate.Thermodynamic database PanAluminumTM is called by this software to simulate the solidification process to obtain the rich supply of data about thermal physical properties of aluminum alloys.The typical key points can be tracked automatically for different alloys designed by user,and then they are used to calculate CSC(Cracking Susceptibility Coefficient)value.The developed software has functions of Single Point Module and Area Module.(2)For common Al-Si,Al-Cu,Al-Mg and Al-Zn binary systems,the prediction results indicate all CSC curves have "A-shaped" peaks at about 0.22wt.%Si,0.74 wt.%Cu,1.55 wt.%Mg and 13 wt.%Zn respectively.The calculated CSC values in this study are in excellent agreement with the other prediction from literature and experimental data from our HTS test and literature.(3)For Al-i binary alloy,the HTS(i)max was determined by adopting HTS test,and CSC(i)max was calculated by software.Then,for multicomponent aluminum alloys,a modification factor Fn was used to modify the calculated CSC values by the software,(?),in which,Fi(i=Si,Cu,Mg,Zn,Fe,Mn)are 1,1.29,1.64,0.22,0.97,1.76 respectively.(4)Contour maps of hot tearing tendency of Al-Cu-Si,Al-Si-Mg and Al-Cu-Mg alloys are predicted by Area Module.For Al-Cu-Si ternary alloy,one severe hot tearing sensitive zone is observed at 0.4?1.5wt.%Cu and 0-0.3wt.%Si and two ridge peaks are at Cu=0.75wt.%and Si=0.2wt.%.There are two hot tearing sensitive zones in Al-Si-Mg ternary system and the hot tearing tendency is decreased with Si content.For Al-Mg2Si pseudo-binary system,if Mg is rich a little,there is strip zone that is not prone to hot tearing.For Al-Cu-Mg ternary systems,there is a large and severe hot tearing zone at 0-0.7wt.%Cu and 0.8-2.8wt.%Mg with CSC prediction of 2.8,and at the same time,there is only small trigonum at 3.4?5.0wt.%Cu and 1.0-3.3wt.%Mg that is not prone to hot tearing.The prediction results for ternary aluminum alloy in this study are in good agreement with the experimental data of ours and from literature as well as the prediction data from literature.The above results indicate the developed CSC prediction software for multicomponent aluminum alloys is reliable and accurate.(5)The CSC predictions for four series of commercial aluminum alloys:Al-Cu-Mg-Si,Al-Mg-Zn-Cu,Al-Mg-Zn-Cu-Mn and Al-Si-Cu-Mg alloys,were calculated by Area Module.Addition of Si in Al-Cu-Mg alloy can improve the hot tearing tendency and also dwindle the hot tearing zone,even disappear.For Al-Mg-Zn-Cu alloy,addition of Cu can efficiently suppress the hot tearing sensitive zone in a low Mg content less than 1wt.%which remises the sensitive effect of Mg on hot tearing.In Al-Si-Cu alloy,addition of Mg can't change the hot tearing zone but enhances the hot tearing tendency.