ELECTROLYTIC NICKEL-PLATING FOR SURFACE PROTECTION AGAINST HIGH-TEMPERATURE OXIDATION AND DECARBURIZATION

In steel research, as well as in the manufacture of semi-finished metallurgical products and finished formed products, such as forged parts, the material is often heated to high temperatures which leads to surface oxidation and decarburization. Material-technological modelling involves the use of small-size specimens which are treated according to schedules identical to those in real-world processing. From these treated specimens, test bars are made for various mechanical tests. If severe decarburization occurs, the affected surface layer may give rise to substantially different results of mechanical testing than in a thermomechanically treated material with an intact surface. Therefore, protective barriers were sought by which formation of scale on the surface of test specimens, and decarburization in subsurface layers could be prevented. One of the available options involves depositing a coating of 10-15 micrometre thickness by electrolytic nickel-plating. By this simple and readily-available technique, very good protection was obtained for specimens exposed to high temperatures.