Patent ID: 6099668
Filing Date: 2000-08-08
Classification: C21D,C22C,F01L

Abstract:
A method for producing an exhaust valve comprising the steps of:subjecting a raw material of a heat resisting alloy consisting by weight percentage of 0.01 to 0.1% of C, not more than 2% of Si, not more than 2% of Mn, 12 to 21.2% of Cr, 0.2 to 2.0% in total of Nb and Ta, not more than 3.5% of Ti, 0.5 to 3.0% of Al, 25 to 45% of Ni, 0.52 to 5.0% of Cu, and the balance being Fe plus incidental impurities to solid solution treatment;forming a head portion of the exhaust valve from the solution treated raw material through cold working or warm working;joining a stem portion made of martensitic heat resisting steel to said head portion of the exhaust valve; andsubjecting the head portion and the stem portion joined with each other to aging treatment.