Patent ID: 7284308
Filing Date: 2007-10-23
Classification: C21D,Y10S,Y10T

Abstract:
1. A production process for a leaf spring for a car, the process comprising: holding a spring main body made from a spring steel in which a Brinell hardness is under 555 HBW and not less than 388 HBW, the hardness of the spring steel corresponding to a diameter of under 2.70 mm of hardness and not less than 3.10 mm of hardness on a Brinell ball mark, at 150° to 400° C.; applying a load to the spring main body in a direction that is the same direction of a load to be applied in actual use; and performing a first shotpeening at a plane of the spring main body where a tensile stress is applied to the spring body, wherein the tensile stress of 1200 to 1900 MPa is applied by the load.