AIT Welder 2nd Period Practice Test

Ductility in steel generally decreases as carbon content increases. Adding more carbon strengthens the iron lattice and promotes harder microstructures like pearlite and cementite, which resist dislocation motion. This makes the material stiffer and more brittle, so it can withstand less plastic deformation before fracturing. Low-carbon steels are mostly ferrite with some pearlite, allowing more slip and greater elongation, while higher carbon steels have more hard phases that reduce ductility. So the best answer is that ductility decreases with more carbon.