| 摘要 |
PROBLEM TO BE SOLVED: To obtain a product having high corrosion resistance to acid, seawater, chemicals or the like by subjecting an austenitic stainless steel product to fluoriding treatment while being heated and infiltrating carbon atoms therein to form a concentrated layer of carbon to a specified depth. SOLUTION: An austenitic stainless steel product is charged to a muffle furnace 1, gaseous fluorine such as NF3 is introduced therein, and it is subjected to fluoriding treatment while being heated. Next, the gas is drawn out of an exhaust tube 6 by the operation of a vacuum pump, which is made nonpoisonous in an exhaust gas treating device 14 and is released to the outside. Then, a carburizing gas is introduced into the muffle furnace 1, and infiltrating treatment of carbon is executed at 400 to 500 deg.C to form a concentrated layer of carbon on the surface layer of a depth of about 5 to 50μm from the surface of the stainless steel. After that, the gas is exhausted. The maximum carbon concn. of the concentrated layer of carbon is preferably regulated to 1.2 to 2.6wt.%. The austenitic stainless steel preferably contains molybdenum. Moreover, the topmost surface layer is preferably removed after the infiltrating treatment.
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