Composition for reducing the removal of material by pickling in the pickling of metal surfaces that contain galvanized and/or ungalvanized steel

An aqueous composition for reducing corrosive removal of material in pickling of metallic surfaces comprising bare and/or galvanized steel, wherein the composition comprises a mixture of a compound of formula I

• R1O—(CH2)x—C≡C—(CH2)y—OR2 (I),
• in which R1 and R2 are both H and a compound of the formula I in which R1 and R2 are each, independently of one another, an HO—(CH2)w— group with w≥2, wherein x and y are each, independently of one another, from 1 to 4 in each of the two compounds of the formula I,
• wherein a mixing ratio in % by weight of the compound of the formula I in which R1 and R2 are both H and the compound of the formula I in which R1 and R2 are each, independently of one another an HO—(CH2)w— group with w≥2 is in a range from 0.5:1 to 2:1 (calculated as 2-butyne-1,4-diol and 2-butyne-1,4-diol bis(2-hydroxyethyl) ether),
• wherein the composition additionally comprises at least one compound of formula II
• R1O—(CH2)x—S—(CH2)y—OR2 (II),
• in which R1 and R2 are each, independently of one another, an HO—(CH2)w— grows with w≥2 and x and y are each, independently of one another, from 1 to 4.