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文章从两方面研究了灰口铸铁大型钢锭模(9.8吨和7.1吨)的失效原因。一是组织上的变化,以确凿的事实和显微照片证明了:使用后的钢锭模从内壁开始,珠光体严重的球化、石墨片氧化,在石墨片周围形成疏松的硅锰氧化物区,使内壁的力学性能首先降低,在反复使用、冷热急剧变化的恶劣条件下,是造成内壁裂纹源的重要原因。二是研究了钢锭模残余应力的变化规律,对铸造态,时效态和退火态的钢锭模分别做了残余应力的测定和分析。结果表明;铸造态残余应力最大,时效态和退火态残余应力变小。但文章认为,致使钢锭模失效报废的原因,主要是循环使用于冷热急剧变化条件下的热应力作用的结果,与残余应力的关系不大。对钢锭模经退火或时效可以提高寿命的传统看法提出了质疑,认为根据不足,此工艺完全可以省去。
In this paper, the failure causes of gray cast iron large steel ingots (9.8 tons and 7.1 tons) were studied from two aspects. First, the organizational changes, with solid facts and photomicrographs proved that: after the use of ingot mold from the inner wall, pearlite serious ball, graphite sheet oxidation, in the graphite sheet around the formation of loose silicomanganese oxide zone , So that the inner wall of the mechanical properties of the first to reduce, in repeated use, abrupt changes in hot and cold conditions, is an important cause of the source of cracks in the wall. Second, the variation of residual stress in ingot mold was studied. Residual stresses were measured and analyzed in cast ingot, aging and annealing ingot mold respectively. The results show that the residual residual stress is the largest in the as-cast state and the residual stress in the aged and annealed state becomes smaller. However, the article argues that the cause of invalidation of the ingot mold failure is mainly the result of the thermal stress under the condition of abrupt change of hot and cold cycles, which has little to do with the residual stress. The traditional view that the ingot mold can be annealed or aged to increase its life expectancy is questioned, which, according to the deficiency, can be completely eliminated.