Did you know…
What central wing structure did Grumman use to replace the F-111's steel?
Short answer
With a single-piece central wing carry-through structure in electron-beam welded Ti-6Al-4V titanium alloy, spanning 6.71 m. That wing box was manufactured in titanium and electron-beam welded at Grumman's plant in Bethpage, Long Island.

The Tomcat's titanium box
The F-14's central wing carry-through structure is a single piece electron-beam welded from Ti-6Al-4V titanium alloy, spanning 6.71 m. The wing box was manufactured in titanium and electron-beam welded at Grumman's facility in Bethpage, Long Island. About 25% of the aircraft's structure is titanium: the wing box, the pivots and the wing's upper and lower skins. A large fixed glove carries the outer wing pivot, with the two spaced 17 feet 10 inches apart.
What it did inherit from the F-111
The F-14 derived from Grumman's initial Model 303 design and reused the TF30 engines from the F-111B, as well as incorporating the large AWG-9 radar and AIM-54 Phoenix missiles, both carried over from the F-111B. The weight targets for the two versions of the F-111 proved too optimistic, and excess weight burdened the F-111B throughout its development.
A structure that survived crashes
The wing box was so physically strong that in many F-14 crashes it was the only part of the airframe that survived intact. Variable-sweep wing technology appeared on several aircraft, including the XF10F, the F-111, the MiG-23/27 and the B-1 bomber, but it is probably the Grumman F-14 Tomcat that is most associated with it.
More questions

Aviation history
Which was the most-produced American fighter of the Second World War?
The Republic P-47 Thunderbolt, of which 15,636 or 15,683 units were built, depending on the source. It was also one of the heaviest fighters of the conflict… more…

Aviation history
Who flew the E-66 at 2,149 km/h?
Konstantin or Vladimir Kokkinaki, depending on the source. Konstantin is credited with the absolute record on a closed 100 km circuit, at 2,148.66 km/h, set… more…

Fly-by-Owen (CC BY SA), vía commons Aviation history
How many I-11Bs were built?
Between 208 and around 450, depending on the source: one of the AISA I-11 reference sheets gives 208 examples built, while All-Aero speaks of around 400 built… more…

Aviation history
How many HH-53s could be converted to Pave Low III?
Eight HH-53C aircraft received an improved systems package and were redesignated HH-53H Pave Low III. The other figure in circulation, nine MH-53H and 32… more…

SCDBob (CC BY SA), vía commons Aviation history
What did the A129 Mangusta's armor protect?
The fuselage: the A129's airframe is armored and, according to All-Aero, designed to protect against 12.7 mm rounds, with partial protection against 23 mm… more…

Fly-by-Owen (CC BY SA), vía commons Aviation history
What landing gear and canopy did the AISA I-11B have?
According to one account, AISA reduced the cockpit canopy and fitted tailwheel gear on the production I-11B. All-Aero claims the opposite: the I-11B was… more…