A method for increasing tensile strength of a cold workable alpha-beta titanium alloy comprises solution heat treating a cold workable alpha-beta titanium alloy in a temperature range of T.sub.106 C. to T.sub.72.2 C. for 15 minutes to 2 hours; cooling the alpha-beta titanium alloy at a cooling rate of at least 3000 C./minute; cold working the alpha-beta titanium alloy to impart an effective strain in the range of 5 percent to 35 percent in the alloy; and aging the alpha-beta titanium alloy in a temperature range of T.sub.669 C. to T.sub.517 C. for 1 to 8 hours. Fastener stock and fasteners including solution treated, quenched, cold worked, and aged alpha-beta titanium alloys are also disclosed.

The present invention relates to a method for producing a subassembly having a form-fitting connection with a precipitation-hardened form-fitting region as well as a corresponding subassembly, wherein at least two components of a subassembly are provided that are connected together in form-fitting manner, wherein each of the components has a form-fitting region that can come in contact with at least one other form-fitting region of the other component to be connected, in order to produce a form-fitting connection by limiting at least one degree of freedom of movement of the connected components relative to one another, wherein at least one of the components has at least one deformation form-fitting region for providing the form-fitting connection that is reshaped for producing the form-fitting connection after arranging the components to be connected relative to one another, in order to produce the form-fitting connection.

The present invention relates to a method for producing a subassembly having a form-fitting connection with a precipitation-hardened form-fitting region as well as a corresponding subassembly, wherein at least two components of a subassembly are provided that are connected together in form-fitting manner, wherein each of the components has a form-fitting region that can come in contact with at least one other form-fitting region of the other component to be connected, in order to produce a form-fitting connection by limiting at least one degree of freedom of movement of the connected components relative to one another, wherein at least one of the components has at least one deformation form-fitting region for providing the form-fitting connection that is reshaped for producing the form-fitting connection after arranging the components to be connected relative to one another, in order to produce the form-fitting connection.

A method for increasing tensile strength of a cold workable alpha-beta titanium alloy comprises solution heat treating a cold workable alpha-beta titanium alloy in a temperature range of T.sub.-106 C. to T.sub.-72.2 C. for 15 minutes to 2 hours; cooling the alpha-beta titanium alloy at a cooling rate of at least 3000 C./minute; cold working the alpha-beta titanium alloy to impart an effective strain in the range of 5 percent to 35 percent in the alloy; and aging the alpha-beta titanium alloy in a temperature range of T.sub.-669 C. to T.sub.-517 C. for 1 to 8 hours. Fastener stock and fasteners including solution treated, quenched, cold worked, and aged alpha-beta titanium alloys are also disclosed.

A method for increasing tensile strength of a cold workable alpha-beta titanium alloy comprises solution heat treating a cold workable alpha-beta titanium alloy in a temperature range of T.sub.-106 C. to T.sub.-72.2 C. for 15 minutes to 2 hours; cooling the alpha-beta titanium alloy at a cooling rate of at least 3000 C./minute; cold working the alpha-beta titanium alloy to impart an effective strain in the range of 5 percent to 35 percent in the alloy; and aging the alpha-beta titanium alloy in a temperature range of T.sub.-669 C. to T.sub.-517 C. for 1 to 8 hours. Fastener stock and fasteners including solution treated, quenched, cold worked, and aged alpha-beta titanium alloys are also disclosed.

In at least one embodiment, an assembly is provided comprising a first member including a 6xxx series aluminum alloy heat treated to have a yield strength of at least 200 MPa and an r/t (bendability) ratio of up to 0.4. One or more members may be secured to the first member with a rivet (e.g., a self-piercing rivet). The heat treated alloy may have a yield strength of at least 260 MPa and may have a bendability ratio of up to 0.3. A method of forming an assembly is also provided, including heat treating a 6xxx series aluminum alloy to produce an alloy having a yield strength of at least 200 MPa and an r/t (bendability) ratio of up to 0.4 and riveting a member including the heat treated alloy to one or more additional members.

In at least one embodiment, an assembly is provided comprising a first member including a 6xxx series aluminum alloy heat treated to have a yield strength of at least 200 MPa and an r/t (bendability) ratio of up to 0.4. One or more members may be secured to the first member with a rivet (e.g., a self-piercing rivet). The heat treated alloy may have a yield strength of at least 260 MPa and may have a bendability ratio of up to 0.3. A method of forming an assembly is also provided, including heat treating a 6xxx series aluminum alloy to produce an alloy having a yield strength of at least 200 MPa and an r/t (bendability) ratio of up to 0.4 and riveting a member including the heat treated alloy to one or more additional members.

A fastening structure includes a first structural member, a second structural member, and a fastening member. The first structural member includes a composite material, and has a first electrically-conductive surface having electric conductivity. The second structural member has a second electrically-conductive surface. The second electrically-conductive surface is in contact with the first electrically-conductive surface and has electric conductivity. The fastening member penetrates the first electrically-conductive surface and the second electrically-conductive surface, and fastens the first structural member and the second structural member.

A joined structure includes a first component, a second component, and an insert. The first component is formed of a fiber-reinforced material and has a hole defining an axis. The second component is adjacent the first component and has a hole aligned with the hole of the first component. The insert is positioned in the hole of the first component. The insert includes an inner layer having a tubular shape about the axis, a middle layer concentrically adjacent to the inner layer about the axis, and an outer layer concentrically adjacent to the middle layer about the axis. The layers are formed of fiber-reinforced materials. One of a boundary between the inner and middle layers and a boundary between the middle and outer layers has a nonlinear profile in a direction parallel to the axis.

A joined structure includes a first component, a second component, and an insert. The first component is formed of a fiber-reinforced material and has a hole defining an axis. The second component is adjacent the first component and has a hole aligned with the hole of the first component. The insert is positioned in the hole of the first component. The insert includes an inner layer having a tubular shape about the axis, a middle layer concentrically adjacent to the inner layer about the axis, and an outer layer concentrically adjacent to the middle layer about the axis. The layers are formed of fiber-reinforced materials. One of a boundary between the inner and middle layers and a boundary between the middle and outer layers has a nonlinear profile in a direction parallel to the axis.