QPQSM (SALT BATH NITRIDING)
Salt bath nitriding, or Quench-Polish-Quench, (QPQ) is particularly important to companies such as oil field service firms whose parts operate for extended periods in highly corrosive environments and are subject to high levels of friction.
QPQSM provides excellent corrosion protection of cast iron and steel components and is an effective and environmentally acceptable alternative to chrome and cadmium coatings.
QPQSM is a diffusion process that provides distortion-free dimensional stability while hardening the surface of the part (up to three times the strength of carbon steel) thereby producing superior wear resistance, improved fatigue strength, and surface lubricity.
The term “QPQ,” or Quench-Polish-Quench is based on a sequence of process events that occur directly following the nitrocarburizing cycle. It begins with the treating cycle of the nitrocarburizing segment, i.e. pre-heat, Nu-Tride salt, Kolene KQ-5OO salt bath quench, which produces a layer of epsilon iron nitride.
The next step is a mechanical polish of the nitride layer, thus restoring the original surface finish. This may be accomplished by vibratory polishing, lapping, centerless polishing, or by other similar means. Finally, to optimize the corrosion resistance, the component is then re-immersed in the KQ5OO salt quench bath for 20-30 minutes, rinsed and oil dipped. The overall QPQ process gives the work piece a cosmetically appealing matte black finish.
LP&C is the only company authorized to provide the remarkable salt bath nitriding, or QPQSM corrosion protection process services in Louisiana.