鋼塊鑄型に就て
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概要
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The materials of Ingot mould are one of the largest factor affecting the economical operation of the steel works. To obtain a good result on this point we should supply cheap moulds sufficiently and reject the old moulds that have got damages on the inner surface, or prefer a suitable material to the mould that will give more durable life. Hence for the former reason I selected the moltem metal of the blast furnace and performed, so called, direct casting, and have found this very profitable. I made also some consideration upon their appliances. For the latter purposes I studied the sand mould for casting, and the variation of the chemical and physical properties affected by repeated heatings on the special cast iron containing Si, Cr and Mn in different percentages. From these results I decided the most suitable compositions for ingot moulds. The conclusions abstracted are as follows : -1. Taken 44% molten iron directly from the blast furnace and mixed with 56% cupola iron, 2, 600kg. square ingot mould was cast. In practical use of the mould 4% loss in life and 9% gain in cost have been proven. If we take 20% of the residual molten steel from the converter or open hearth furnace and 80% of the molten iron from the mixer, casting a mould with the composition of C below 3% Si about 4% I am sure it will be more economical giving a suitable material for the mould. 2. Some improvements in sand moule give a strong and hard casting, but they cannot prevent the changes of the materials by repeated heatings. 3. Silicon content of about 2.5% gives the worst result, but decreasing Si a little and increasing C, or adding more Si and subtracting C will give better results. Si 3.5∿5%, C below 3% gives the best results, Carbon must always be below the eutectic percentage of the ternary equilibrium diagram of Fe-C-Si. 4. Chromium increases the hardness and strength of the casting and prevents the altering of the characteristic of the materials by heat. The composition must be changed according to the Si percentage. When the composition are as follows Si Cr C 3.5 2.0 3.3 2.5 1.3 3.4 2.0 1.0 3.9 1.5 0.4 3.4 on repeated heating until 800℃, the expansion and contraction are reversible and the changes of hardness, strength, and structure by repeated heatings are the least. But when Cr increased more, cementite appears and casting becomes brittle accompanied by internal stress which result the destruction of the mould when the hot molten steel are cast. In such cases it is prevented by annealing the mould at 600℃ for 4 hours. 5. It is such better to add Cr with more Si content. 6. It is preferable to have less Mn as this element increases the changes of the materials by repeated heatings.
- 社団法人日本鉄鋼協会の論文
- 1928-01-25
著者
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