GB920896A - A method of producing workpieces required to exhibit high strength at room and at elevated temperatures - Google Patents

Abstract

A method of producing a hot extrusion, drop forging or like die or tool or component stressed at high temperature and made of an alloy containing more than 50% nickel or nickel and cobalt and up to 45% chromium and at least one of the elements iron, manganese, aluminium molybdenum, tungsten, vanadium, titanium, niobium, tantalum, silicon and carbon in quantity not exceeding a total of 40% comprises the steps of successively reducing the workpiece by hot working, e.g. by forging, upsetting or pressing, to a shape exceeding the final dimensions by between 10 and 20% subjecting the workpiece to a solution heat treatment at 1,050 to 1,200 DEG C. for 1 to 10 hours, cooling the preformed workpiece directly from the said temperature to a temperature below the recrystallization point and within the range 600 DEG to 700 DEG C. and then reducing the workpiece to its final dimensions and finally subjecting the workpiece to a precipitation hardening treatment at between 650 DEG and 800 DEG C. for 10 to 20 hours. In an example, a precipitation hardenable austenitic alloy is hot worked into a disc or plate-shaped die blank having dimensions exceeding the desired final dimensions by 13.5%. The blank is solution heat treated at 1,150 DEG C. for 2 hours and then cooled to 650 DEG C. at which temperature the blank is reduced to its final dimensions by upsetting. Finally, the blank is heat treated at 700 DEG C. for 16 hours to effect the precipitation hardening. The alloys contain not more than 1% C., not more than 5% titanium and silicon, and none of said additional elements should exceed 25%. Minor quantities of nitrogen, copper and rare earth metals may be included. The alloys may contain alloying components in the following quantities:- .Chromium.Up to 30% .Molybdenum.Up to 10% .Tungsten.Up to 10% .Vanadium.Up to 5% .Titanium.Up to 5% .Niobium and tantalum.Up to 10% .Aluminium.Up to 6% .Silicon.Up to 3% .Manganese.Up to 3% .Nitrogen.Up to 0.5% .Boron.Up to 0.5% .Zirconium.Up to 0.5% .Iron.Up to 10%