| 摘要 |
PURPOSE: To manufacture a long service life C hook for pickling enabling continuous use for long term by hot-forging a steel having a specific composition regulating the contents of Ni, Cr and Mo and executing machining. CONSTITUTION: A steel ingot composed of, by wt.%, <=0.08% C, <=1.00% Si, <=2.00% Mn, <=0.030% P, <=0.030% S, <=3.00% Cu, 10.0-15.0% Ni, 15.0-19.0% Cr, 1.0-4.0% Mo, <=0.010% O and the balance Fe with impurity elements is hot-forged into a specific shape at about 1000-1250 deg.C and >=3 forging ratio. Successively, after executing solid solution heat treatment, the last finish working is applied by machining and the surface roughness after machining is desirable to be <=3μm Rmax . By this method, in a pickling apparatus used to both of acid solution and salt solution, the C hook obviating the exchange is obtd. at a low cost.
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