Premature Corrosion of Steak Knives Due to Extensive Precipitation of Chromium Carbides

Abstract

Steak knives from three different suppliers were brought to our facility to conduct a comparative analysis of their metallurgical properties. Although they have allegedly been used and cleaned in similar conditions in several restaurants across North America, only knives coming from one supplier showed signs of premature corrosion. Our investigation found that even though they have similar chemical and mechanical properties, and had been submitted to the same heat treatment, major microstructure discrepancies made some of these knives prone to rapid corrosion. As per our examination, the prematurely corroded knives experienced extensive chromium carbides precipitation during heat treatment, which determined a massive chromium depletion of the matrix and lowered their corrosion resistance. On the contrary, the knives that never corroded kept all their chromium content inside the matrix, thus contributing to better corrosion resistance.