Patent ID: 7670444

Claim:
A non-heat treated and hot forged steel product having easy fracture splitting, consisting essentially of: by weight, C: 0.3-0.46%, Si: 0.5-2.0%, Mn: 0.3-1.5%, P: 0.05-0.15%, Cr: 0-1.0%, V: 0-0.4%, Al: 0-0.05%, N: 0.005-0.03% and the balance being Fe and inevitable impurities, provided that: (1) the contents of C, Mn and Cr fulfill the following condition: 1.40(C %)+0.28(Mn %)+0.50(Cr %)≧0.75 (2) the pearlite area fraction is 50% or more, and (3) the shape of the product being a combination of two or more components of a machine part with a notch or notches provided by processing with a thermal source that increases brittleness of the non-heat treated and hot forged steel product at bottom portions of the notch or notches, the thermal source being selected from the group consisting of laser, electron beam, plasma arc, TIG, and equivalents thereof; the product being easily split by fracture upon application of load, whereby fracturing starts from the notch or notches to separate the two or more components into distinct parts, wherein forging accurcacy is improved by hot coining or hot sizing during the hot forging at a temperature of 600° C. or higher.