The factor cosφ cosλ that converts a tensile stress into the resolved shear stress on a slip system, where φ and λ are the angles of the slip-plane normal and the slip direction to the tensile axis. Its maximum is 0.5.
Japanese name: シュミット因子
Schmid factor appears in 2 practice questions across 1 topic, including Strengthening mechanisms and dislocations.
Answer: B. For neighboring grains to deform without opening gaps or overlapping at the grain boundaries, at least five independent slip systems must operate in each grain, including poorly oriented ones
In a polycrystal, if each grain deformed into any shape it liked, gaps and overlaps would open at the grain boundaries. To accommodate an arbitrary change of shape at constant volume, five independent slip systems are needed (the von Mises criterion). As a result, poorly oriented systems must operate along with those of high Schmid factor, and averaging over a randomly oriented FCC polycrystal gives a Taylor factor of about 3.06. If yielding were set only by the most favorably oriented grains, a factor larger than 2 could not be explained. The Taylor factor is set by the distribution of grain orientations and does not depend on grain-boundary area or grain size; the effect of grain size is added separately through the Hall–Petch relationship. The same criterion explains why polycrystals of HCP metals, which lack enough independent slip systems, have poor ductility.
As a result, poorly oriented systems must operate along with those of high Schmid factor, and averaging over a randomly oriented FCC polycrystal gives a Taylor factor of about 3.06.
The yield stress σy of an FCC polycrystal is about three ti…The resolved shear stress on a slip system is τ = σ cosφ cosλ (Schmid's law), and cosφ cosλ is called the Schmid factor.
A single-crystal rod is pulled in tension. For a slip syste…Critical resolved shear stress Taylor factor Hall–Petch relationship Bauschinger effect Dispersion strengthening Orowan mechanism Peierls stress