This is the second part of a two-part article. Read Part I. If you examine the mechanical properties of several materials, including carbon steel, alloyed steel, stainless steel, as they relate to roll forming, you'll gain an understanding of the influence of some primary metal processes on roll forming.
Alloyed Steel
In addition to carbon, large varieties of metallic and nonmetallic elements are used to achieve the desired mechanical properties and corrosion resistance. The most frequently used alloying elements are manganese, cobalt, chromium, copper, molybdenum, vanadium, nickel, zirconium, and titanium.
The yield strength of the different high-strength, low-alloy (HSLA) steels is in the range of 60,000 to 120,000 PSI. The yield strength of the dual-phase martensitic steels can be as high as 180,000 to 220,000 PSI.
High-strength alloyed steels have unusual properties, strength, and springback that generate challenges for roll formers. In some cases, 25 degrees or more of overbend is required to achieve a 90-degree bend.
Furthermore, specifications cover only the minimum mechanical properties. Maximum yield can be considerably higher than the specified minimum, and it can fluctuate from coil to coil or even within a coil.
