材料期刊网

<正> 从1957年4月起,鞍钢曾在初轧机轧制钢3沸腾钢中板坯时,发现板坯上起鼓包的现象,在生产中叫作“气囊”。气囊的位置都相当于钢锭的头部。仔细的检查证明,在一部份未发现气囊的头部板坯的横断面上,特别是在氧气-乙炔切断的横断面上,也可以看出有分层现象,就是说在板坯厚度的中线附近有或长或短的、形状不规则的缝(图1),宽度大多在1mm以下,但也有较宽的,直到形成明显的气囊。这些缺陷都发生在正常的板坯切

An extraordinarily large gas pocket formed during the rolling of a rimming steel slab wasstudied. Results of investigation indicated that the serious lamination defects that often occurredin such slabs were due to the presence in large rimming steel ingots of central cavities that (1) con-tained gases at high pressure, (2) were surrounded by heavily segregated metal, and (3) wereloaded at their surfaces with non-metallic substances. During the rolling operation these cavitiesfailed to weld up. On the contrary, the solid walls dividing neighbouring cavities were pushedopen and, as a result, a large discontinuity remained in the rolled slab. It was found that aftershearing the slab and thus exposing the discontinuity to atmosphere, in most cases such discon-tinuities could weld up during subsequent rolling into plates. Lower tapping temperature and lower pouring temperature (speed) were found effective tolessen lamination rejects.