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.
Claims18
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 made of a steel comprising between 0.3 wt % and 0.77 wt % Carbon and the hardened case has a first microstructure comprising ferrite and martensite having a residual stress between 400 MPa and 550 MPa, and wherein the plurality of journals have been heated to an intercritical temperature of between 724° C. and 822° C.
A crankshaft for an internal combustion engine, the crankshaft comprising:
- a main journal having a surface and a hardened case, wherein the hardened case penetrates into the main journal from the surface to a depth, wherein the main journal is comprised of steel having between 0.3 wt % and 0.77 wt % Carbon, and wherein the surface of the main journal has been heated to an intercritical temperature of between 724° C. and 822° C. and the surface of the main journal has been cooled at a cooling rate between 15 to 20° C./sec.
A crankshaft for an internal combustion engine, the crankshaft comprising:
- a main journal having a surface and a hardened case, wherein the hardened case penetrates into the main journal from the surface to a depth, wherein the main journal is comprised of steel having between 0.3 wt % and 0.77 wt % Carbon, and wherein the surface of the main journal has been heated to an intercritical temperature of between 724° C. and 822° C. and the surface of the main journal has been cooled such that the hardened case has a microstructure comprising between 15 wt % and 30 wt % ferrite with the balance of martensite.
Dependencies are inferred from the claim text.