| 摘要 |
PROBLEM TO BE SOLVED: To reduce a cost and further, to lighten a working load by dissolving the conventional problem in a porous plug in a ladle refining for melting a stainless steel with which the wearing of the porous plug at the early time is prevented. SOLUTION: The main body 5 of the porous plug 1 is formed of a refractory composed of 91% Al<SB>2</SB>O<SB>3</SB>, 7% SiO<SB>2</SB>and the balance impurities and having 35.2% porosity and 34 MPa compressive strength. At the most top part of the main body 5 of the porous plug 1, the porosity for preventing an infiltration during an RH treatment, i.e. a permeability is lower than that of the main body, and the refractory of material having a little infiltration of the molten steel, e.g. a first layer in the infiltration preventive part 2 is formed with a refractory composed of 94% MgO, 3% SiO<SB>2</SB>and the balance impurities and having 4.9% porosity and 40 MPa compressive strength. COPYRIGHT: (C)2004,JPO
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