| 摘要 |
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 0.002 inch of their original integration and thereafter, while the cap and body portions are free to laterally adjust, applying a clamping load through the bolts to force the fractured ridges into exact rematch. |
