| 摘要 |
PROBLEM TO BE SOLVED: To prevent generation of flow rust and to early produce corrosion resistant stabilized rust improving corrosion resistance by holding an environment of a specified oxygen gas composition while forming a water film of a specified thickness on a steel surface. SOLUTION: While forming a water film of <=500μm thickness on a steel plate surface, an environment of 15-50 vol% gaseous oxygen thereon. A steel 1 is held in a rust forming bath 2, voltage of a humidifying pump 12 is continuously changed so that an output value of a water film thickness detection sensor 13 set to a dummy test piece 1D surface is coincide to an objective value, a water film thickness is maintained fixed by feed-back control changing a water spray quantity to a water content adjustment chamber 3 communicating to a rust forming bath 2. The atmosphere in the rust forming bath 2 is a mixed one between a gaseous nitrogen 7 and gaseous oxygen 8, by changing a partial pressure of the gaseous oxygen 8 with using a gas supply device 6, the gaseous oxygen in the atmosphere is adjusted. Pure water is used for spraying in order to produce efficiently obtain stabilized rust.
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