鋳鋼の引け巣の最下点及びザク巣の予知
スポンサーリンク
概要
- 論文の詳細を見る
This paper presents the methods for predicting the lowest position of the shrinkage cavity and porosities in steel castings. Casting defects caused by volume contraction during solidification of the molten metal are categorized into "Shrinkage Cavity" and "Porosity", depending on their generation mechanisms. The "Fluid Critical Solid Fraction Ratio Method" (flimit Method) is proposed to predict the lowest position of the shrinkage cavity, and the "Solid Fraction Ratio Gradient Method" (fs Gradient Method) is proposed for porosity prediction. By combined use of the above two method, a comprehensive approach to predicting any type of shrinkage defect can be synthesized. The flimit Method states that the lowest position of the shrinkage cavity corresponds to the fading point of the flimit contour line. With 0.67 as the flimit, the calculated and experimental results correspond closely. The fs Gradient Method is based on the concept that porosities are generated by volume contraction of a large quantity of interdendritic molten metal which remains at the fading stage of the flimit contour line. Since the fs gradient is defined in this study along the direction from the flimit contour fading point toward outside, the existence of a large quantity of molten metal corresponds to a low fs gradient. The porosity region observed in the experiment and the region where the calculated gradient was less than 0.25 (1/cm) were almost identical. For the general application of the proposed method, the following three types of shrinkage defect generation patterns are considered to be the most fundamental of the various types of shrinkage cavity and porosity generation in the casting : (1) generation of an isolated shrinkage cavity, (2) generation of both a shrinkage cavity and porosities, and (3) generation of a secondary shrinkage cavity. The proposed methods are verified synthetically through comparison between numerical calculations and experiments with respect to the above-mentioned three fundamental patterns. Furthermore, the "Solidification Temperature Method" and the "Temperature Gradient Method", which have been widely used for practical problems, are theoretically examined to clarify their applicability and limitations. The "Solidification Temperature Method" can only predict the lowest position of the shrinkage cavity for castings in which the flimit fading point and final solidification point have the same location. The "Temperature Gradient Method" may be more applicable to porosity prediction than shrinkage cavity prediction, since the low fs gradient defined in this study corresponds to a low temperature gradient. However, if the influence of the temperature distribution change of the casting during the time interval between flimit contour fading and solidification termination is included in the "Temperature Gradient Method", the accuracy of the method will improve.
- Japan Foundry Engineering Societyの論文
Japan Foundry Engineering Society | 論文
- 球状黒鉛鋳鉄の延性破壊に及ぼす応力３軸度及び基地組織の影響
- 紡織機鋳物の鋳造法に就いて (其の一)
- 光ファイバで紫外線を導光した光造型機の開発と石こう鋳造への適用
- 薄肉球状黒鉛鋳鉄の黒鉛粒数に及ぼす元湯硫黄量，冷却速度及び希土類元素添加時期の影響
- Fe-Si合金及びFe-C-Si合金の塩浴窒化に及ぼすSiの影響とFe，Siの窒化物について