振動對鑄鐵鑄造製程之組織及殘留應力的影響研究

Study on the Influence of Vibration on the Structure and Residual Stress of Cast Iron Casting Process

林啟明(Chi-Ming Lin)；楊湘豐(Hsiang-Fong Yang)；樓紹緯(Shao-Wei Lou)；周燕龍(Yen-Lung Chou)；吳威德(Weite Wu)

鑄鐵 ； 振動 ； 冷卻曲線 ； 應力消除 ； Cast iron ； Vibration ； Cooling curve ； Stress relief

鑄造工程學刊

45卷3期（2019 / 09 / 01）

13 - 24

繁體中文

本研究導入同步振動技術來優化亞共晶鑄鐵的顯微結構特徵，並結合不同溫度下的振動應力消除技術，來探究溫度對應力消除之影響。本研究使用CE值=3.9（3.6%C ,1%Si）的鐵－碳－矽合金，在1350°C進行澆鑄，利用具備高頻特徵在不同激振力的振動條件下凝固至600°C，並對鑄鐵凝固過程進行熱分析與觀察鑄態下各相的分佈、成份與孔隙率進行討論，最後以鑄態組織較佳者在不同溫度下再進行模內應力消除。實驗結果表明隨著激振力與主波振幅增加，則冷卻曲線所得之共晶開始的過冷度、凝固和凝固結束溫度有明顯降低趨勢。當振動條件為38 Hz L時，高頻次波振幅達主波1/2，與未振動者相比較，最低共晶過冷溫度略降、共晶反應時間變長、固液共存區內溫度差減少7.4°C。在各相區之石墨共晶胞與白口組織中的碳、矽重量百分比差異得知，碳由14.32%縮減至11.77%，矽由0.16%縮減至0.06%。38 Hz L同步振動鑄造技術可有效改善鑄件斷面組織的均勻性，消除鑄造過程中的反冷現象，使石墨共晶胞均勻分佈，並得到孔隙率最優之鑄件。將材料以38 Hz L同步振動鑄造至600°C後，於不同溫度實施模內振動應力消除至40°C，經Cr靶X-ray測量晶格間繞射角度後以cosα法計算殘留應力值，發現於200°C模內振動應力消除，即可達到最佳消除效果，應力值為92MPa。

This study introduces the synchronous vibration technique which optimizes the microstructure characteristics of hypoeutectic cast iron. It combines vibration stress reliefs at different temperatures to effect the temperature on stress relief. In this study, an iron-carbon-silicon alloy with a CE value of 3.9 (3.6% C, 1% Si) is casted at 1350 °C. We use high-frequency vibration to solidify the alloy to 600 °C under different vibrational conditions, thermal analysis of cast iron solidification process and distribution, as well as composition and porosity of each phase in as-cast state. Finally, in the as-cast structure, the in-mold stress relief is performed at different temperatures. The thermal results show that as the excitation force and the amplitude of the main wave increase, the under-cooling temperature, the solidification and the solidification ending temperature of the eutectic obtained by the cooling curve decrease remarkably. When the vibration condition is 38 Hz L, the high frequency wave reaches 1/2 of the main wave. Comparing with the non-vibration hypoeutectic cast iron, the minimum eutectic under-cooling temperature decreases slightly, the eutectic reaction time becomes longer, and the temperature difference in the solid-liquid coexistence zone decreases by 7.4 °C. The difference in the weight percentage of carbon and silicon between the graphite eutectic cells and the carbidic white structure region shows that the carbon is reduced from 14.32% to 11.77%, and the silicon is reduced from 0.16% to 0.06%. The 38 Hz L synchronous vibration casting technique can effectively improve the uniformity of the cross-section structure of the casting, eliminate the anti-cold phenomenon in the casting process, make the graphite eutectic cells evenly distributed, and obtain the casting with the best porosity. After the material was synchronously vibrated at 38 Hz L to 600 ° C, the in-mold vibration stress was removed to 40 ° C at different temperatures. The residual stress value was calculated by cosα method after measuring the inter-lattice diffraction angle by Cr target X-ray. It is found that the vibration elimination stress in the mold at 200 °C can achieve the best elimination effect, and the stress value is 92 MPa.

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