Steel excellent in resistance to sulfuric acid dew point corrosion and preheater for air

The present invention provides a high temperature to a low temperature from the entire temperature range has excellent resistance to sulfuric acid dew point corrosion of steel, and a heat transfer assembly for use in an air preheater, containing by weight percent, C : ≤0.20%, Si: 1.2 ~ 3.5%, Cu: 0.05 ~ 1.0%, Sb: 0.01 ~ 0.30%, Mn: ≤1.0%, P: ≤0.05%, S: ≤0.05%, Al: ≤0.10%, N: ≤0.050%, and the remaining portion containing incidental ingredients and / or Fe, unavoidable impurities has excellent corrosion resistance to sulfuric acid dew point of the steel. The steel further contains in weight% of Cr: ≤1.0%, Mo: ≤1.0%, Ni: ≤0.5%, Nb: ≤0.1%, V: ≤0.1%, Ti: ≤0.1%, Sn: 0.01 ~ 0.2 %, B: 0.0005% to 0.010%, or more than one.