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防爆电机的毛坯,除了机壳用钢板焊接或铸钢铸造之外,还有部分零件如端盖、轴承盖等是用HT25-47铸铁铸造的。十年来,我们采用广西土铁,云南、贵州土焦,生产JBT、JBJ、1JB、BJO2、JBT2等系列部分规格的铸件,由于土焦的固定联低,仅有60%左右,而灰分高,平均高达25~30%,挥发物在10%以下,含S高达2.3~2.8%。土铁合S也高,C、Si元素含量波动大。所以,炉温难于提高,铁水温度偏低,很难进行孕育处理;五个主要元素难控制,机械强度经常低于标准,以致产生废品。针对以上问题,经过几年摸索后,找出了一些方法,现在简介如下: 一、关于主要元素的控制五个主要元素C、Mn、Si、S、P在铸铁件中的含量和铸铁的结晶形式,对铸件的机
Explosion-proof motor rough, in addition to the shell welded steel plate or cast, there are parts such as end caps, bearing caps, etc. are cast with HT25-47 cast iron. In the past ten years, we have adopted some specifications of castings such as JBT, JBJ, 1JB, BJO2 and JBT2 from Guangxi Tietui, Yunnan and Jiaozhou, and only 60% An average of 25 to 30%, less than 10% of volatiles, containing up to 2.3 to 2.8% S. Soil iron S is also high, C, Si element content fluctuations. Therefore, the furnace temperature is difficult to improve, the hot metal temperature is low, it is difficult to conceive treatment; five main elements difficult to control, mechanical strength often below the standard, resulting in waste. In response to the above problems, after several years of exploration, to find out some of the methods, are summarized as follows: First, the control of the main elements of the five main elements of C, Mn, Si, S, P content in iron castings and cast iron crystallization Form, on the casting machine