Resistance of steel-teeming stoppers

Conclusions

In order to make spalling-resistant stoppers which can be used to teem metal satisfactorily, the charge at the refractory shop of the Nizhnly Tagil Metallurgical Combine should include 7–10% chamotte coarser than 2 mm and 45–50% finer than 0.54 mm. The temperature should be raised from 30 to 150° at the rate of 5–7°/hr, and from 800 to 1200° at the rate of 20–25°/hr. The holding time at 1280–1300° should be 10 hours.

When laying down new specifications for standards for steel-teeming stoppers, it is essential to stipulate a porosity of 15–20% at refractoriness-under-load of 2 kg/cm² of not less than 1320 or not more than 1380°