| 摘要 |
PROBLEM TO BE SOLVED: To obtain a steel excellent in an acoustic property and quietness by making an acid insoluble impurity less than a specified pieces per unit steel when dissolving, in a mixed acid aqueous solution heated to a specified temp, the steel which contains a specified content in each of C, Si, Mn, Cr, Al and the balance Fe with inevitable impurities, and restricts Ti, O in the impurities to a specified content. SOLUTION: A content, by weight, is 0.6-1.2% C, 0.1-2.0% Si, 0.1-2.0% Mn, 10.0-14.0% Cr, <=0.04% Al. Ti, O in the impurities, by weight, <=0.0015% T, <=0.0012% O. A mixed acid aqueous solution is prepared by mixing, by mass, 60% nitric acid, 96% sulfuric acid, pure water in the volume ratio of 25:1:55 and heating to 90-95 deg.C. An acid insuluble impurity includes Al2 O3 of 50%, and its size is >=15μm major diameter and is less than 19 pieces in 10 g of the steel. In the case corrosion resistance is not required, a Cr content is 0.8-2.0%, and in the case of needing that of medium degree, it is 2.0-10.0%.
|
