Steel is composed of mostly the element, Iron (Fe). More than 95% of steel is Iron with the balance being composed of other elements the most important of which is Carbon.
Carbon steel are steels whose alloying elements do not exceed the following percentages:
Stainless steel is steel that does not stain thus is called "Stainless Steel". It is corrosive resistant and does not rust as readily as ordinary carbon steels. Stainless steel has a minimum of 11% chromium by weight. Austenitic or 300 series grades are the most prevalent and have a minimum of 16 % chromium and a maximum of .15 % carbon. 316 L is the most common 300 series grade with the L meaning less than .03 % carbon in the 300 series. Nickel is added to stabilize the Austenitic structure making the steel non magnetic. Manganese does the same as nickel but at a lower cost. To add more strength the amount of carbon is increased.
Quality Bar buys Hot Rolled Bars from the mills. The most common grade produced by the mills is 1018 which is a low carbon steel. Quality Bar stocks some 1018 but more 1045 which has a carbon content of .45 % and is a mid carbon steel.
1045 is a four digit number used by the American Iron and Steel Institute (AISI) to describe carbon steel The first two digits 10 stand for non-resulfurized. The last two digits stand for the percents of carbon or .45 %.
If the first two digits were 11 it would stand for resulfurized. If 12 it would mean resulfurized and rephosphorized. If 15 it would mean non-sulfurized with Mn being greater than 1%.
Letters between the second and third digit further describes the steel. V stands for Vanadium, B for Barium and L for Leaded steels. 10V45, which Quality Bar stocks, is non-resulfurized with .15 % vanadium and .45 % carbon and is a medium carbon steel.
1018 is a low carbon bar widely used in shafting. It has relatively low strength but is easily formed, easily machined, and easily welded. 1045 is a medium carbon steel also used in shafting but where higher strength is required, it is also used to make hydraulic cylinders. 1144 is a medium carbon steel with high manganese, excellent machine ability but is difficult to weld. 4140 is even a higher strength steel than 1045, is very tough and is well suited to heat treating - it is very wear resistant. 8620 has high core strength, good ductility, is very hard and weldable.
Low carbon steels and high alloy steels have relatively the same density, 7.85 kg/m3 and the same approximate weight, 450 lbs. per cubic foot. Alloy steels have a higher yield points 366 to 1793 compared to low carbon steels of 86 to 388 MPa. Alloy steels have a higher tensile rating 758 to 1882 compared to low carbon steels of 276 to 1882 MPa. Alloy steels will have a higher Brinell hardness 149 to 627 compared to low carbon steels of 86 to 388. The modules of elasticity are similar 190 to 210 GPa.