球墨鑄鐵凝固縮孔模擬模組之驗證

The Validation of solidification shrinkage models for Ductile Iron Casting

陳宇宏(Yu-Hung Chen)；許富淵(Fu-Yuan Hsu)

球墨鑄鐵凝固 ； 凝固模擬模組驗證 ； 石墨體積膨脹 ； 熱點區域 ； 斷面硬度分佈 ； 冒口設計 ； ductile cast iron ； shrinkage model validation ； graphite volumetric expansion ； hot-spot ； hardness contour test ； feeder design

鑄造工程學刊

45卷3期（2019 / 09 / 01）

25 - 38

繁體中文

本研究是應用兩種凝固模擬模組經由三種冒口方案設計的球墨鑄造實來驗證其準確性。發現只有所謂的第一原則（First Principle model）的數值模擬模組包含了追蹤獨立液體區域三維型體隨凝固過程的變化外，也考慮了球墨鑄鐵液體的流動及球狀石墨體積膨脹等現象。實際鑄造這三種冒口方案的球墨鑄件，在分別的鑄件中心剖面上，每間隔5mm處進行2維的硬度分佈的測量，找尋在中心剖面的實際縮孔的外形及位置。證實了模擬所追蹤的縮孔位置即是凝固過程中殘留液體在當時凝固鑄件的最低處。也提出凝固模擬與實際鑄件之縮孔外形上的差異原因。應用這個經過驗證後的第一原則數值凝固模組，來模擬分析正方型鑄件（鑄件模數為16.67mm）所需要的冒口模數為17.84mm。此冒口與鑄件模數比為1.07比一般短的固液區間（共晶成分）的合金所需要的冒口模數還低，此亦證明此模組有考慮石墨膨脹的現象。對於此正立方形鑄件之冒口補縮效率為12.21%。又由內插凝固模擬結果得出，預測鑄造時實際球墨鑄鐵的實際碳含量。這種內插法，可以補足長期實際量測球墨鑄件碳含量不準確的問題。

In this study, two solidification shrinkage models were validated by three feeder designs of ductile iron castings. It was found that the so called First Principle model is a model not only tracking the isolated liquid region in 3 dimension but also considering the residual liquid flowing and the volumetric expansions of spheroidal graphite during the solidification of ductile iron castings. After casting the three feeder designs of ductile iron castings, the hardness in every 5 mm distances within the central cross-section of the three castings were measured. The actual shrinkage contour and locations on the central plane of the castings were discovered. It shows that the shrinkage profile and locations predicted by the modeling are the shape and places where the residual liquid in the lowest liquid level within an isolated regions during solidification. The difference of shrinkage profiles between the actual casting and the modeling were explained. Applying the validated model (First principle model), an optimized feeder design (with a modulus of 17.84mm) for cube-shaped cast with a modulus of 16.67mm was found. In this optimized feeder design, the modulus ratio of the feeder and cast is 1.07 which is much lower than that required by short feeding range alloy. This implies that the graphite volumetric expansion somehow helps the feeding of ductile iron casting. In this feeder design, its feeding efficiency is 12.21%. In tuning carbon simulation, a precise carbon composition can be predicted by the modeling.

1. Flow 3D Casts, Flow Science, https://www.flowsciences.com/ 2018.06
2. Campbell, J.(2011).complete casting handbook.
3. Fredriksson, H.,Stjerndahl, J.,Tinoco, J.(2005).On the solidification of nodular cast iron and its relation to the expansion and contraction.Materials Science and Engineering A,413-414,363-372.
4. Hsu, Fu-Yuan,Lin, Huey-Jiuan(2011).Foam filters used in gravity casting.Metallurgical and Materials Transactions B,42(6),1110-1117.
5. Richins, D.S.,Wetmore, W.O.(1952).Hydraulics applied to molten aluminum.Trans. ASME,725-732.
6. Schmidt, W. A.,Sullivan, E.,Taylor, H. F.(1954).AFS Trans,9,70.

1. 馮玉麟,許富淵,洪啟銘(2022)。鑄件型體與模具常數驗證之研究。鑄造工程學刊，48(2)，11-24。
2. 馮玉麟,許富淵,洪啟銘(2023)。重力鑄造模具數位輔助設計系統。機械工業雜誌，489，41-45。