IF (Interstitial-Free steel): Steel produced with very low amounts of interstitial elements (primarily carbon and nitrogen) with small amounts of titanium or niobium added to tie up the remaining interstitial atoms. Without free interstitial elements, these steels are very ductile and soft, will not age or bake harden, and will not form strain (Lüder’s) lines during forming due to the absence of YPE (yield point elongation).

Mechanical Properties

Fatigue Properties

Strain-Life Fatigue Curves