METHOD FOR EVALUATING RESISTANCE TO CORROSION OF STEEL PRODUCT

摘要

PROBLEM TO BE SOLVED: To provide a method for evaluating the resistance to the corrosion of steel products for vehicle bodies driven in cold regions assuming regions to which a Mg-based snow melting salt agent is applied in a method for evaluating the resistance to the corrosion of steel products or steel products to which a surface treatment including zinc is applied through the use of Mg-based salt.;SOLUTION: In the method for evaluating the resistance to the corrosion of steel products or steel products to which a surface treatment including zinc is applied through the use of Mg-based salt, their resistance to the corrosion is evaluated by repeating processes constituted of the following process (a) and process (b) a plurality of times. In the process (a), a solution including at least NaCl, sulfate ions, and MgCl₂; having a pH of 3.0 to 5.0; having chlorides having a total concentration of 0.1 to 2.0 wt.% in the solution, and of which the NaCl concentration is three times the concentration of MgCl₂ or less is adhered to the surface of a steel product within the range of a processing time of 1 to 15 minutes. The process (b) comprises both a drying process at a relative humidity of 10 to 50% for 3 to 12 hours and a wetting process at a relative humidity of 80 to 98% for 2 to 8 hours. One cycle of the drying process and the wetting process within a temperature range of 10 to 60°C with the temperature of the drying process equal to or greater than the temperature of the wetting process, having a set transition time of 20 to 60 minutes included in a drying process time from the wetting process and the drying process is performed once or a plurality of times.;COPYRIGHT: (C)2005,JPO&NCIPI