Crankshaft and method of manufacture
AssigneeGM Global Technology Operations LLC
InventorsJianghuai Yang, James D. Cremonesi, Paul J. Gelazin, Qigui Wang, Daniel J. Wilson
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Abstract
A method for manufacturing a crankshaft for an internal combustion engine with a plurality of journals having a hardened case with a first microstructure. The crankshaft is comprised of a steel comprising between about 0.3 wt % and 0.77 wt % Carbon. The first microstructure of the hardened case of the journals comprises between about 15% and 30% ferrite and a balance of martensite and the resultant subsurface residual stress between 310 MPa and 620 MPa.
Claims20
A crankshaft for an internal combustion engine, the crankshaft comprising a plurality of journals each comprising a surface and a hardened case, and wherein the crankshaft is further comprised of a steel having up to about 0.77 wt % Carbon and the hardened case has a first microstructure comprising ferrite and martensite.
A method for manufacturing a ferrous workpiece, the method comprising:
- providing a machined workpiece comprised of a steel comprising up to 0.77 wt % Carbon, and wherein the workpiece comprises a first journal having a surface;
- heating the surface of the first journal to an intercritical temperature;
- and
- quenching the surface of the first journal with a quench medium achieving a cooling rate between 15 to 20° C./sec.
A crankshaft for an internal combustion engine, the crankshaft comprising a plurality of journals each comprising a surface and a hardened case, and wherein the crankshaft is comprised of a steel comprising between about 0.3 wt % and 0.77 wt % Carbon and the hardened case has a first microstructure comprising between about 15% and 30% ferrite and a balance of martensite.
Dependencies are inferred from the claim text.