不锈钢铸造工艺的两大基本特点
一、
1.
由于不锈钢精细铸造的缩短大大超过铸铁,为避免铸件呈现缩孔、缩松缺点,在铸造工艺上大都选用冒口和、冷铁和补助等办法,以完成次序凝结。
Because the shortening of stainless steel precision casting is much more than that of cast iron, riser, chill and subsidies are mostly used to complete the sequential solidification in order to avoid the defects of shrinkage cavity and porosity.
为避免不锈钢铸件发生缩孔、缩松、气孔和裂纹缺点,应使其壁厚均匀、避免尖角和直角结构、在铸型用型砂中加锯末、在型芯中加焦炭、以及选用空心型芯和油砂芯等来改进砂型或型芯的让步性和透气性。
In order to avoid shrinkage, porosity, porosity and cracks in stainless steel castings, uniform wall thickness, sharp angle and right angle structure, sawdust addition in mold sand, coke addition in mold core, hollow core and oil sand core should be selected to improve concession and air permeability of sand mold or core.
二、
Two.
由于钢液的流动性差,为避免铸钢件发生冷隔和浇缺乏,铸钢件的壁厚不能小于8mm;选用干铸型或热铸型;恰当进步浇注温度,一般为1520°~1600℃,由于浇注温度高,钢水的过热度大、保持液态的时间长,流动性可得到改进。可是浇温过高,会引起晶粒粗大、热裂、气孔和粘砂等缺点。
Because of the poor fluidity of molten steel, the wall thickness of steel castings should not be less than 8 mm in order to avoid cold separation and lack of pouring. Dry or hot moulds should be selected, and the proper progressive pouring temperature should be between 1520 and 1600 degrees Celsius. Because of the high pouring temperature, the superheat of molten steel is high and the time of liquid holding is long, the fluidity can be improved. However, too high pouring temperature can cause coarse grain, hot cracking, porosity and sand sticking.
因此一般小型、薄壁及形状杂乱的精细铸造件,其浇注温度约为钢的熔点温度+150℃;浇注体系的结构力求简略、且截面尺度比铸铁的大;大型、厚壁铸件的浇注温度比其熔点高出100℃左右。
Therefore, the pouring temperature of small, thin-walled and disorderly-shaped fine castings is about the melting point temperature of steel + 150'; the structure of the pouring system is simple and the section size is larger than that of cast iron; the pouring temperature of large and thick-walled castings is about 100'.