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在铸钢件的生产中,经常用外冷铁配合冒口来调整铸件各部的冷却速度,尤其是难以用冒口补缩的地方,使型腔内的钢水向冒口方向顺序凝固,防止铸件产生缩孔、缩松等缺陷。但在北方的气候条件下,铸型出窑后,外冷铁随温度下降,表面吸附水分氧化而生成铁锈,在高温金属液的作用下产生如下反应: 2Fe(OH)_3→Fe_2O_3+3H_2O↑上式右端将氧化铁液,析出的H_2和CO很难排出,故极易产生皮下气孔。为了使外冷
In the production of steel castings, often with the outer cooling iron with riser to adjust the cooling rate of the various parts of the casting, especially in the riser is difficult to fill the place, so that the cavity of the molten steel to the direction of the riser to the order of solidification to prevent casting Produce shrinkage, shrinkage and other defects. However, in the north of the climate conditions, the mold after the kiln, the outer cold iron decreases with temperature, the surface adsorption of water oxidation and the formation of rust, the role of high temperature molten metal produced the following reaction: 2Fe (OH) _3 → Fe_2O_3 + 3H_2O ↑ On the right side of the iron oxide solution, precipitated H_2 and CO is difficult to discharge, it is easy to produce subcutaneous pores. In order to make the cold