LOW-EXPANSION Fe-Ni ALLOY FOR SEMI-TENSION MASK, SEMI-TENSION MASK OF THE ALLOY, AND COLOR PICTURE TUBE USING THE MASK

摘要

A low-expansion Fe-Ni based alloy for semi-tension masks with excellent creep properties consists of, in mass percentage, from 34 to 38% Ni, from 0.01 to 0.5% Mn, from 0.0003 to 0.0015% B, from 0.0010 to 0.0050% N, and the balance Fe and unavoidable impurities. The alloy further includes from 0.005 to 0.20% Si and from 0.005 to 0.030% Al. Among the unavoidable impurities, C, P and S are controlled to no more than 0.010%, no more than 0.015%, and no more than 0.010%, respectively. The alloy is subjected, at least once after hot rolling or after cold rolling, to annealing in a non-oxidizing atmosphere at between 650 and 750° C. for from 30 minutes to less than 5 hours. The alloy is subjected to stress relief annealing after final cold rolling. A semi-tension mask using the alloy and a color picture tube using the semi-stretched-tension mask, are also provided.