Patent ID: 7803236

Claim:
A cold forged titanium valve spring retainer, comprising: 0.8 wt %≦Fe≦1.2 wt %; 0.24 wt %≦O≦0.32 wt %; 0.02 wt %≦N≦0.05 wt %; wherein the balance consists essentially of titanium, the valve spring retainer including a large diameter part, a small diameter part coaxially joined integral to a peripheral part of the large diameter part, a tapered part coaxially joined integral to a peripheral part of the small diameter part, the large diameter part having a diameter ranges from 1.5 cm to 2.5 cm, and an axial thickness that ranges from 1 mm to 2 mm, the small diameter part having an axial thickness that is greater than the axial thickness at the large diameter part, the tapered part having an axial thickness that is greater than the axial thickness at the large diameter part, wherein the valve spring retainer has a cross sectional hardness that is greater than or equal to 230 HV0.1 in Vickers hardness, and wherein prior to an oxidation treatment over an outer surface of the valve spring retainer the average grain size is less than or equal to 20 μm.