NON-DESTRUCTIVE METHOD FOR DETECTING MACHINING BURNS OF A VERY-HIGH-STRENGTH STEEL, AND COLOUR CHART FOR CALIBRATING MACHINING BURNS OF SAID STEEL

摘要

A method for efficient, industrialisable detection of machining burns of VHS steel. Machined steel is immersed in an aqueous solution of acids including hydrofluoric acid and nitric acid. To define a burn degree, a color chart for calibrating machining burns of VHS steel detected using the method is prepared. The color chart can include studs of the examined steel subjected to deliberate damage by excessive resurfacing actions (or other machining modes), then submerged in the acid solution. The resurfacing actions can be simulated by overheated thermal treatment, between an ageing temperature (for example 510° C. for steel) and a solution annealing temperature (950° C. for the steel). The samples are classified according to the grey level thereof resulting from the immersion and corresponding to a predetermined hardness and thus to a predetermined level of damage.