Vacuum heat treatment offers an alternative method to traditional salt-bath and controlledatmosphere furnace hardening techniques for high strength steels, such as AISI 4340M and 300M. However, heat treaters must be prudent when choosing between oil and gas quenching for vacuum hardening of high strength steels, because each process has its advantages and disadvantages. High strength steel alloys, such as 4340M, 300M, and others, are most commonly used in the manufacture of landing gear components. These alloys are hardened and tempered to produce ultimate tensile strengths exceeding 280 ksi (1,930 MPa). By Jeff Pritchard and Scott Rush - VAC AERO International Inc., Oakville, Ontario, Canada

The Thermal Processing Divisions of VAC AERO International have provided repair services for damaged components from land-based and aerospace gas turbine engines. Engine manufacturers, operators, overhaul centers and commercial airlines are just a few of the customers that depend on these services. Many hot section engine components are fabricated from nickel-based superalloys. These materials cannot be repaired by traditional techniques, such as welding, without causing significant reductions in mechanical properties. As a result, VAC AERO developed proprietary vacuum brazing techniques to repair cracks, wear and other service-induced damage. By Jeff Pritchard - Vac Aero International Inc.

Stretching the service life of a hot zone-one of the most expensive consumables in a vacuum furnace-is of prime importance to the furnace owner. Proper care and maintenance can slow down hot-zone deterioration, which directly translates to cost savings. Hot-zone service life is directly related to the type of heat treating process used in a vacuum furnace and to the severe thermal stresses imposed by continuous vacuum-furnace cycles. Distortion and contamination are the main factors causing a breakdown of hot-zone components. Distortion is inevitable because thermal cycling is inherent to the process. However, periodic inspection and remediation of hot-zone components together with thorough component cleaning can extend service life. By Bill Potts, Vac-Aero International Inc., Oakville, Ontario, Canada