摘要 |
An improved lubricating layer for heavy cold working of iron and steel objects can be obtained by first phosphating them with a solution comprising, in percentages by weight, 0.3 to 2.5 % of zinc ions, 0.01 to 2.0 % of ferrous ions, 0.5 to 5.0 % of phosphate ions, 0.7 to 12.0 % of nitrate ions, and 0.02 to 0.25 % of water soluble aromatic organic compounds that contain both nitro and sulfonic groups, with the ferrous ion and zinc ion contents additionally being such that the weight ratio of ferrous ions to zinc ions in the phosphating solution in within the range from 0.005 to 3.0. Optionally, the phosphating solution may also contain from 0.2 to 2.0 % of calcium ions, and when it does, the weight ration of calcium ions to zinc ions in the solution should also be in the range from 0.7 to 4.0. After phosphating, the phosphated surfaces are treated with a conventional lubricant, preferably a weakly alkaline solution of sodium stearate. |