Method for fabricating an article of an alpha-beta titanium alloy by forging

A method for fabricating an article of a titanium-base alloy for a gas turbine application, comprising the steps of

• providing a starting ingot having a thickness of at least about 20 inches, wherein the starting ingot is made of a titanium-base Ti-6Al-4V alloy having a temperature-composition phase diagram with a beta-phase field and an alpha-beta phase field;
• thereafter
• first forging the starting ingot in the beta-phase field to form an in-process billet;
• thereafter
• second forging the in-process billet in the alpha-beta phase field;
• thereafter
• heating the in-process billet into the beta-phase field to recrystallize the in-process billet;
• thereafter
• third forging the in-process billet, wherein the step of third forging includes a step of
• forging the in-process billet from a first forging thickness of not less than about 15 inches to a second forging thickness of not more than about 13 inches, at a third-forging temperature of from about 1600° F. to about 1700° F. to develop a fine alpha grain size of about 5 micrometers or less;
• thereafter
• fourth forging, in a closed forging die, the in-process billet to form a semi-finished article, wherein the step of fourth forging is performed at a fourth-forging temperature of from about 1550° F. to about 1725° F.;
• and thereafter
• heat treating the semi-finished article prior to further processing for gas turbine applications.

A method for fabricating a disk of a titanium-base alloy, comprising the steps of

• providing a starting ingot having a thickness of at least about 20 inches, wherein the starting ingot is made of a titanium-base Ti-6Al-4V alloy having a temperature-composition phase diagram with a beta-phase field and an alpha-beta phase field;
• thereafter
• first forging the starting ingot in the beta-phase field to form an in-process billet;
• thereafter
• second forging the in-process billet in the alpha-beta phase field;
• thereafter
• heating the in-process billet into the beta-phase field to recrystallize the in-process billet;
• thereafter
• third forging the in-process billet to a forged billet, wherein the step of third forging includes a step of
• forging the in-process billet from a first forging thickness of not less than about 15 inches to a second forging thickness of not more than about 13 inches, at a third-forging temperature of from about 1600° F. to about 1700° F. to develop a fine alpha grain size of about 5 micrometers or less;
• thereafter
• fourth forging, in a closed forging die, the in-process billet to form a semi-finished gas turbine disk, wherein the step of fourth forging is performed at a fourth-forging temperature of from about 1550° F. to about 1725° F.;
• and thereafter
• heat treating the semi-finished disk, wherein the step of heat treating includes the steps of
• solution heat treating the semi-finished disk at a solution-heat-treating temperature of from about 1550° F. to about 1725° F., and thereafter
• stress relieving the semi-finished disk at a stress-relieving temperature of from about 1000° F. to about 1300° F.

A method for fabricating a disk of a titanium-base alloy, comprising the steps of

• providing a generally cylindrical starting ingot having a cylindrical diameter of at least about 30 inches and a cylindrical surface, wherein the starting ingot is made of a titanium-base Ti-6Al-4V alloy having a temperature-composition phase diagram with a beta-phase field and an alpha-beta phase field;
• thereafter
• first forging the starting ingot in the beta-phase field to form a generally cylindrical in-process billet by applying a first-forging primary forging force;
• thereafter
• second forging the in-process billet in the alpha-beta phase field by applying a second-forging primary forging force;
• thereafter
• heating the in-process billet into the beta-phase field to recrystallize the in-process billet;
• thereafter
• third forging the in-process billet by applying a third-forging primary forging force, wherein the step of third forging includes a step of
• forging the in-process billet from a first forging thickness of not less than about 15 inches to a second forging thickness of not more than about 13 inches, at a third-forging temperature of from 1600° F. to about 1700° F. to develop a fine alpha grain size of about 5 micrometers or less;
• thereafter
• sectioning the in-process billet perpendicular to a cylindrical axis of the generally cylindrical in-process billet, to form a sectioned in-process billet;
• upset forging the sectioned in-process billet by applying a primary upsetting force in a direction parallel to the cylindrical axis, to form an upset in-process billet;
• thereafter
• fourth forging, in a closed forging die, the upset in-process billet by applying a fourth-forging primary forging force in the direction parallel to the cylindrical axis to form a semi-finished gas turbine engine disk, wherein the step of fourth forging is performed at a fourth-forging temperature of from about 1550° F. to about 1725° F.;
• and thereafter
• heat treating the semi-finished disk, wherein the step of heat treating includes the steps of
• solution heat treating the semi-finished disk at a solution-heat-treating temperature of from about 1550° F. to about 1725° F., and thereafter
• stress relieving the semi-finished disk at a stress-relieving temperature of from about 1000° F. to about 1300° F.