Rolling Conditions for Annihilation of Micro Porosities and Development of Center-portion Heavy Reduction Rolling

Abstract

The authors investigated the method to get the sound heavy gauge plates only by rolling process, and developed the Low-speed Heavy Reduction Rolling process, the purpose of which was to secure the necessary temperature, time and compressive stress for annihilating micro porosities. Furthermore, taking notice that most of micro porosities are distributed in the about 50-60% region of mid-width of ingots, they have developed the Center-portion Heavy Reduction Rolling process which reduce only the high density area of micro porosities partially by the low speed and heavy reduction rolling. In such a partial rolling, the compressive stress in midthickness increases notably as a result of the binding force caused by the un-rolled edge parts and an increase in the reduction amount per pass.
It would be possible to manufacture the sound heavy gauge plates stably from the conventional ingots by the application of this developed rolling process.