When steel needs to be softened to alter ductility, toughness, or properties, or to produce a specific microstructure, a heat treater can turn to any one or combination of processes to suit the material or the application.
Metlab Heat Treat’s primer series includes a short explanation of the options available, whether it is
annealing, which “removes the internal stresses, which build up as a result of cold working and other fabrication processes;”
protective atmosphere normalizing, which “refines the grain size and enhances the uniformity of the microstructure;” or
spheroidize annealing, which “is generally done on parts which have been work hardened, to allow them to be further worked, either rolled in the case of coils, or drawn for wire.”
1.) Load of torsion bars, manufactured from 4340 steel, normalized in the vertical position to maintain straightness. Parts measure approximately 3\” in diameter by 6\’ long.
2.) 26,000 pounds of low carbon steel flat wire being prepared for spheroidize annealing. Spheroidize annealing is an intermediate processing step to allow the wire to be further rolled to a smaller gage without cracking.
A USAF C-69, the military version of the Constellation
In the aerospace industry, heat treating is an essential step in the manufacturing process. Stress reduction on metal parts to improve the strength and fatigue life of aircraft components is critical to ensure parts stand up to the demands and specifications of aerospace applications. Every aircraft we see in the sky today contains precision-made parts and systems that have undergone heat treatment, whether it’s engine brackets, landing gear, bearings, gears and rods, fuselage, frame parts, brakes, or cooling systems.
Sometimes, however, those involved in modern heat treating processes, such as Metlab, based in Wyndmoor, Pennsylvania, and DELTA H Technologies, LLC, located in Carroll, Ohio, also expand their capabilities and apply their expertise to heat treating parts of historic aircraft in order to restore them to their former glory.
Lockheed L1649A “Super Star”
A DELTA H heat treating system is now being used in a project to make a Lockheed Constellation airworthy. The science of heat treating has not changed, therefore, a state of the art heat treating system is fulfilling the requirement to repair damaged antique aircraft and parts. Using the DELTA H heat treating systemto make this aircraft flight-worthy ensures that the aircraft will be in compliance with AMS2750E.
The Lockheed Constellation is an important piece of U.S. aviation history, a plane used for civilian and military transport, as well as a presidential aircraft for U.S. President Dwight D. Eisenhower.
Ryan ST-A (Aerobatic) training aircraft circa. 1934
Classic Metalcraft recently turned to Metlab for the heat treatment of a newly fabricated structural bulkhead for a Ryan ST-A historic aircraft (circa.1934). Ryan Sport Trainers were the aircraft of choice for sport pilots, flying schools, and the military of other countries.
“The most difficult part that needed to be fabricated was the #2 bulkhead,” said David Paqua of Classic Metalcraft. “Not only is it tough to replicate without heavy pressing equipment, but it requires heat treating by a knowledgeable firm to prevent distortion.”
Bulkhead component prior to heat treating
The bulkhead component is a structural piece fabricated with 4130 steel and located just forward of the instrument cluster, where it bears significant stress. Metlab’s heat treating capabilities ensured that the shape integrity of the part was maintained as well as the aerodynamic characteristics of the aircraft.
Metlab has worked with a number of NASCAR and Indy Racing Car Teams and also companies that restore antique cars, sports and muscle cars and has a history of heat treating race car parts that must endure severe conditions. Big B Manufacturing is a specialty machine shop located in Klingerstown, PA which specializes in design and engineering as well as machining of small and large components. They also make and race off road cars. Big B brought a project to Metlab that required the heat treating of four (4) link arms. The arms are fabricated from 4130 steel and TIG welded with 4130 filler. The suspension parts are for Big B Manufacturing’s racing team.
