Abstract: A crackable forging steel with excellent machinability and low ductility consisting of (by weight percent): 0.6-0.75 carbon, 0.25-0.5 manganese, 0.04-0.12 sulfur, and the remainder essentially iron except for up to about 1.2% residual impurities selected from the group consisting of phosphorous, silicon, nickel, vanadium, copper, chromium, and molybdenum, the manganese/sulfur ratio being greater than 3.0 and the microstructure of said alloy being substantially 100% pearlite with a grain size grade between 3-8 according to ASTM Specification E112-88.A method of making a connecting rod with such steel comprising: (a) forging a rod of such steel; (b) cooling the forging to ensure essentially a 100% pearlitic microstructure and a grain size of 3-8 ASTM per Specification E112-88; (c) fracturing the rod into cap and body portions; (d) reassembling by use of bolts which have a clearance no greater than 0.04 inch to guide the fractured surfaces to within 0.

Abstract: A method of cracking bearing assembles including the steps of (a) forming a ductile metal (steel, aluminum or titanium) connecting rod in one piece (e.g., by hot forging) having an annular wall defining a crankshaft opening with preformed surface crevices for guiding the initiation of a cracking plane that extends across the crank opening; (b) charging (i.e., for about 40 seconds) the region of such wall along at least one portion of the cracking plane with hydrogen by means of an electrolytic cell or by means of reacting the metal rod with a strong acid (e.g., concentrated sulfuric) to cause hydrogen to dissolve in the metal to facilitate hydrogen stress cracking thereat, with or without the imposition of static mechanical tensile loading at such crevices (i.e., for about 40 seconds) of a magnitude insufficient to cause yielding of the metal; and (c) prolonging, increasing, or imposing the static mechanical loading (i.e.