U.S. STEEL FIRMS STUDY USX UNIT PRICE HIKE Two major steel companies said they were studying a price increase announced yesterday by USX Corp's USS steelmaking division. Spokesman for Armco Inc and Bethlehem Steel Corp said the proposed price hike was under study. Yesterday, USS said it plans to raise base prices on plate products by 20 dlrs a short ton, or about five pct, effective with shipments October 4. A spokesman for LTV Steel Co, a unit of LTV Corp, declined comment, adding that the company does not make heavy plate and makes few other plate products.