Critical assessment 41: The strength of undeformed pearlite

Abstract

The dependence of the proof strength of undeformed pearlite on its interlamellar spacing is examined in detail, with a view to resolving the plethora of relationships that exist in the research literature. It is found by the analysis of published data that the Hall–Petch equation is best suited to explain the strength, not simply on the basis of empirical fit, but even when examined in a Bayesian framework. Furthermore, it is the only relationship that gives a physically meaningful value to the friction stress. The reasons why previous analyses have failed to resolve this issue are examined and explained. It is discovered that ferrite in interstitial-free iron is, at an identical length scale, stronger in yield than the ferrite within pearlite.