f Cu content on hot cracking l-Cu System
Figure 3. Graphic outline of the derivation of tR and tV for the C446 alloy (Al-3.6wt% Mg-1.2wt%Mn-0.12wt%Fe)
INDUSTRY NEWS/čĄŒä¸šć–°é—ť
king Model
2. çƒčŁ‚樥型 2.1 樥型的ć??čż° The Hot Cracking Model [7] uses a cracking susceptibility çƒčŁ‚樥型[7]用裂纚ć•?ć„&#x;性糝数(CSC)ć??述了ĺ?ˆé‡‘ćˆ?ĺˆ†ĺŻš uses a cracking coefficient (CSC) to describe the effect of alloy Model [7]coefficient (CSC) tosusceptibility describe the effect of alloy composition on çƒčŁ‚的役ĺ“?。CSC的厚䚉 ot tearing.hot The CSC The is defined as: tearing. CSC is defined as: 2. Hot Cracking Model
2.1 MODEL DESCRIPTION SCRIPTION
đ?‘Ąđ?‘Ąđ?‘Ąđ?‘Ą
đ??śđ??śđ??śđ??śđ??śđ??śđ??śđ??śđ??śđ??śđ??śđ??ś = đ?‘Ąđ?‘Ąđ?‘Ąđ?‘Ą đ?‘Łđ?‘Łđ?‘Łđ?‘Ł
(1)
đ?‘…đ?‘…đ?‘…đ?‘…
me during solidification which thesolidification casting is in ‘‘vulnerable’’ and tR is the Where tv is thein time during which the cast-to cracking, tVć˜Żé“¸äťśĺœ¨ĺ‡?固过程ä¸â€œć˜“裂â€?çš„ć—śé—´ďźŒtRć˜Żç”¨ć?Ľçź“解 is ‘‘vulnerable’’ 应力的旜间。 the stressing relief process. to cracking, and tR is the time available for the stress relief process.
3 spent in 60% to 10% liquid As shown in Figure 3, the time volume range is defined as tR, as mass and liquid feeding will readily occur at this liquid fraction level. A volume fraction of liquid between 10% and 1% was chosen as the vulnerable regime, and the time spend here is defined as tV. At very low volume fractions of liquid, the material will be too strong to crack. In order to predict the variation of the cracking susceptibility coefficient with alloy composition, it is necessary to obtain the fraction liquid (fL) vs. time curves corresponding to a range of initial alloy compositions. To achieve this end, PanEngine[13] and PanAluminum Thermodynamic Database[14] were used to calculate the fL vs. temperature curves. Figure 4 shows the fraction liquid versus temperature curve for the C446 alloy (Al-3.6wt%Mg-1.2wt%Mn-0.12wt%Fe). PanEngine is a collection of C++ classes, which performs thermodynamic and equilibrium calculations. An application program was written in the current study to perform the Scheil solidification simulation and CSC calculation for multicomponent aluminum alloys using PanEngine. The composition- and temperature-dependent liquidus slope and partition coefficient were obtained from PanEngine at each time-step during the simulation. The heat evolution during the solidification process was also obtained from PanEngine. Based on the heat evolution of the alloy, the cooling rates were estimated with a heat flow proportional to the square root of time, dQ/dt � t-1/2. Figure 5 shows the calculated cooling curve for the C446 alloy(Al3.6wt%Mg-1.2wt%Mn-0.12wt%Fe). Once the fL-T curve (Figure 4) and the T-time curve (Figure
匂回3ć‰€ç¤şďźŒĺœ¨é‡‘ĺąžćś˛ä˝“ç§ŻčŒƒĺ›´60至10内所用的旜 间袍厚䚉为tRďźŒĺ› ä¸şĺœ¨čż™ä¸Şä˝“ç§ŻčŒƒĺ›´ĺ›şç›¸ĺ˝˘ćˆ?ĺ’Œé‡‘ĺąžćś˛čĄĽ ĺ……ĺžˆĺŽšć˜“ĺ?‘ç”&#x;ă€‚ĺœ¨é‡‘ĺąžćś˛ä˝“ç§Żĺˆ†ć•°10%ĺˆ°1%䚋间的袍视为 č„†ĺźąçš„é˜śćŽľďźŒĺœ¨ć¤é˜śćŽľć‰€ç”¨çš„旜间袍厚䚉为tVă€‚ĺœ¨é‡‘ĺąžćś˛ ä˝“ç§Żĺˆ†ć•°é?žĺ¸¸ä˝Žçš„ćƒ…ĺ†ľä¸‹ďźŒć??料塲çť?čśłĺ¤&#x;ĺźşč€Œä¸?䟚裂埀。
Figure 4. Fraction liquid versus temperature curve for the C446 alloy(Al3.6wt%Mg-1.2wt%Mn-0.12wt%Fe)
Figure 5. Calculated cooling curve for the C446 alloy(Al-3.6wt%Mg-1.2wt%Mn0.12wt%Fe)
回4ďźšC446ĺ?ˆé‡‘ďźˆAl-3.6wtďź…Mg-1.2wtďź…Mn-0.12wtďź…Feďź‰çš„éƒ¨ĺˆ†ćś˛ 体与渊庌曲线。
5, cooling curve) are calculated, the fraction liquid versus time (fL-time) curve can be easily obtained (Figure 3). The CSC can then be obtained from the fraction liquid versus time (fL-time) curve and Eq. [1]. 126
为了预澋çƒčŁ‚ć•?ć„&#x;çłťć•°éš?ĺ?ˆé‡‘ćˆ?ĺˆ†çš„ĺ?˜ĺŒ–ďźŒćœ‰ĺż…čŚ čŽˇ ĺž—ĺŻšĺş”çš„çłťĺˆ—ĺˆ?始ĺ?ˆé‡‘çť„ćˆ?çš„é‡‘ĺąžćś˛ä˝“ç§Żĺˆ†ć•°ďźˆfL寚 ć—śé—´çš„ć›˛çşżă€‚ä¸şĺŽžçŽ°čż™ä¸€ç›Žçš„ďźŒä˝żç”¨PanEngine[13]ĺ’Œ PanAluminumçƒĺŠ›ĺŚć•°ć?Žĺş“[14]莥玗fL与渊庌的曲线。 回4ć˜ŻC446ĺ?ˆé‡‘çš„é‡‘ĺąžćś˛ä˝“ç§Żĺˆ†ć•°ĺŻšć¸ŠĺşŚçš„ć›˛çşżďźˆAl3.6wtďź…Mg-1.2wtďź…Mn-0.12wtďź…Fe。 PanEngineć˜ŻC ++çąťçš„ć•°ć?Žĺšłĺ?°ďźŒć‰§čĄŒçƒĺŠ›ĺŚĺ’Œĺšł 襥莥玗。盎ĺ‰?çš„ç ”çŠśä¸çź–写了一个应用程ĺş?ďźŒç”¨äşŽä˝żç”¨ PanEngineĺŻšĺ¤šĺ…ƒé“?ĺ?ˆé‡‘čż›čĄŒScheilĺ‡?固樥ć‹&#x;ĺ’ŒCSC莥 çŽ—ă€‚ďźŒä¸Žćˆ?ĺˆ†ĺ’Œć¸ŠĺşŚćœ‰ĺ…łçš„ćś˛ç›¸çşżć–œçŽ‡ĺ’Œĺˆ†é…?糝数䝎 PanEngine樥ć‹&#x;ćœ&#x;é—´çš„ćŻ?个旜间ćĽéŞ¤čŽˇĺž—ă€‚ĺ‡?ĺ›şčż‡ç¨‹ä¸ çš„çƒé‡?释攞äš&#x;䝎PanEngine莡垗。ĺ&#x;şäşŽĺ?ˆé‡‘çƒé‡?ćź”ĺ?˜ďźŒ ç”¨ä¸Žć—śé—´ĺšłć–šć šćˆ?ćŁćŻ”çš„çƒćľ ć?Ľäź°çŽ—冡ĺ?´é€&#x;çŽ‡ďźŒdQ/dt âˆ? t-1/2。回5ć˜ŻčŽĄçŽ—ĺž—ĺ‡şçš„C446ĺ?ˆé‡‘ďźˆAl-3.6wtďź…Mg1.2wtďź…Mn-0.12wtďź…Fe冡ĺ?´ć›˛çşżă€‚
一旌莥玗出fL-Tć›˛çşżďźˆĺ›ž4ďź‰ĺ’Œć¸ŠĺşŚ-ć—śé—´ć›˛çşżďźˆĺ›ž5冡ĺ?´
回5莥玗的C446ĺ?ˆé‡‘ďźˆAl-3.6wtďź…Mg-1.2wtďź…Mn-0.12wtďź…Fe冡 ĺ?´ć›˛çşżă€‚
ć›˛çşżďź‰ďźŒĺ°ąĺ?ŻäťĽĺŽšć˜“ĺœ°čŽˇĺž—é‡‘ĺąžćś˛ä˝“ç§Żĺˆ†ć•°ä¸Žć—śé—´çš„ďźˆfLć—śé—´ďź‰ć›˛çşżďźˆĺ›ž3。焜ĺ?Žĺ?ŻäťĽäťŽé‡‘ĺąžćś˛ä˝“ç§Żĺˆ†ć•°ĺŻšć—śé—´ ďźˆfL-ć—śé—´ďź‰çš„ć›˛çşżĺ’Œç‰ĺź?莡垗CSC[1]。 2.2 MODEL VALIDATION
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