<P> Low - carbon steels suffer from yield - point runout where the material has two yield points . The first yield point (or upper yield point) is higher than the second and the yield drops dramatically after the upper yield point . If a low - carbon steel is only stressed to some point between the upper and lower yield point then the surface develop Lüder bands . Low - carbon steels contain less carbon than other steels and are easier to cold - form, making them easier to handle . </P> <P> Carbon steels which can successfully undergo heat - treatment have a carbon content in the range of 0.30--1.70% by weight . Trace impurities of various other elements can have a significant effect on the quality of the resulting steel . Trace amounts of sulfur in particular make the steel red - short, that is, brittle and crumbly at working temperatures . Low - alloy carbon steel, such as A36 grade, contains about 0.05% sulfur and melts around 1,426--1,538 ° C (2,599--2,800 ° F). Manganese is often added to improve the hardenability of low - carbon steels . These additions turn the material into a low - alloy steel by some definitions, but AISI's definition of carbon steel allows up to 1.65% manganese by weight . </P> <P> Carbon steel is broken down into four classes based on carbon content: </P> <P> 0.05 to 0.309% carbon content . </P>

As the carbon content of carbon steel rises the steel becomes