DECARBURIZATION ANNEALING OF EXTRA-LOW CARBON STEEL FOR SHADOW MASK

摘要

Experimental decarburization annealing showed that yield point elongation in shadow mask can be suppressed when annealing temperature was higher than 760 deg C or drew point was higher than +10 deg C. and hydrogen partial pressure and gas flow rate had little effect on yield point elongation. When the decarburization process was divided by diffusion of carbon in steel matrix and interfacial carbon-gas reaction, the carbon-gas reaction at metal surface was found to be the rate controlling step. In production lines the mid-stacked shadow mask sheets showed higher yield point elongation due to the insufficient penetration of decarburizing atmosphere into the gap. Calculated results showed that accumulated CO gas formed by initial decarburization reaction could increase the solute carbon content in steel.