Quench polish quench (QPQ) is a specialized type of nitrocarburizingcase hardening that increases corrosion resistance. It is sometimes known by the brand name of Tufftride, Tenifer or Melonite.[1] Three steps are involved: nitrocarburize ("quench"), polish, and post-oxidize ("quench").[2]
This process is often used when two or more of the following properties are required in a workpiece:
The process starts with a standard salt bath nitrocarburizing cycle, which produces a layer of ε iron nitride.[4] Next, the workpiece is mechanically polished; typical polishing processes include vibratory finishing, lapping, and centerless grinding. Finally, the workpiece is re-immersed into the salt quench bath for 20 to 30 minutes, rinsed, and oil dipped. This last step optimizes the corrosion resistance by creating a layer of iron oxide about 3 to 4 micrometers thick.[5] It also gives the workpiece a black finish.[3][6]
Corrosion resistanceedit
Field immersionedit
Field immersion comparison chartASTM B117 Salt Spray Test
The chart on the right shows a comparison of corrosion resistance against other surface treatments, based on field immersion tests. Test conditions for the immersion test are full immersion in 3% sodium chloride plus 3 g /L of hydrogen peroxide for 24 hours.[citation needed]
Salt spray testedit
The chart on the right shows a comparison of the corrosion resistance of surface treated steel automotive steering columns based on the ASTM B117 salt spray test.[citation needed]
Referencesedit
^"Melonite/QPQ". HEF Group (USA). 14 June 2012. Retrieved 16 February 2014.
^Davis, Joseph R., ed. (2002). Surface Hardening of Steels: Understanding the Basics. ASM International. pp. 203–204. ISBN9781615032501. Retrieved 16 February 2014.
^ abEasterday, James R. (1996). "The Kolene QPQ(SM) Process". Detroit, Michigan: Kolene Corporation. Retrieved 14 February 2014.
^Liapina, T.; Leineweber, A.; Mittemeijer, E. J. (June 2003). "Nitrogen redistribution in ε/γ′-iron nitride compound layers upon annealing". Scripta Materialia. 48 (12). Elsevier: 1643–1648. doi:10.1016/s1359-6462(03)00136-2.(subscription required)
^"Use Salt Bath Nitriding for Uniform & Consistent Layers". Kennebunk, Maine: Northeast Coating. Retrieved 16 February 2014.
^"QPQ Liquid Nitriding". Edmonton, Alberta: Thermex Metal Treating Ltd. 2010. Retrieved 16 February 2014.
External linksedit
April 12, 2024
quench, polish, quench, specialized, type, nitrocarburizing, case, hardening, that, increases, corrosion, resistance, sometimes, known, brand, name, tufftride, tenifer, melonite, three, steps, involved, nitrocarburize, quench, polish, post, oxidize, quench, th. Quench polish quench QPQ is a specialized type of nitrocarburizing case hardening that increases corrosion resistance It is sometimes known by the brand name of Tufftride Tenifer or Melonite 1 Three steps are involved nitrocarburize quench polish and post oxidize quench 2 This process is often used when two or more of the following properties are required in a workpiece wear resistance corrosion resistance fatigue strengthCommon applications of the process are for piston rods of shock absorbers cylinders and rods for hydraulic systems pumps axles spindles firearm slides and barrels and valves 3 Contents 1 Process 2 Corrosion resistance 2 1 Field immersion 2 2 Salt spray test 3 References 4 External linksProcess editThe process starts with a standard salt bath nitrocarburizing cycle which produces a layer of e iron nitride 4 Next the workpiece is mechanically polished typical polishing processes include vibratory finishing lapping and centerless grinding Finally the workpiece is re immersed into the salt quench bath for 20 to 30 minutes rinsed and oil dipped This last step optimizes the corrosion resistance by creating a layer of iron oxide about 3 to 4 micrometers thick 5 It also gives the workpiece a black finish 3 6 Corrosion resistance editField immersion edit nbsp Field immersion comparison chart nbsp ASTM B117 Salt Spray TestThe chart on the right shows a comparison of corrosion resistance against other surface treatments based on field immersion tests Test conditions for the immersion test are full immersion in 3 sodium chloride plus 3 g L of hydrogen peroxide for 24 hours citation needed Salt spray test edit The chart on the right shows a comparison of the corrosion resistance of surface treated steel automotive steering columns based on the ASTM B117 salt spray test citation needed References edit Melonite QPQ HEF Group USA 14 June 2012 Retrieved 16 February 2014 Davis Joseph R ed 2002 Surface Hardening of Steels Understanding the Basics ASM International pp 203 204 ISBN 9781615032501 Retrieved 16 February 2014 a b Easterday James R 1996 The Kolene QPQ SM Process Detroit Michigan Kolene Corporation Retrieved 14 February 2014 Liapina T Leineweber A Mittemeijer E J June 2003 Nitrogen redistribution in e g iron nitride compound layers upon annealing Scripta Materialia 48 12 Elsevier 1643 1648 doi 10 1016 s1359 6462 03 00136 2 subscription required Use Salt Bath Nitriding for Uniform amp Consistent Layers Kennebunk Maine Northeast Coating Retrieved 16 February 2014 QPQ Liquid Nitriding Edmonton Alberta Thermex Metal Treating Ltd 2010 Retrieved 16 February 2014 External links edit Retrieved from https en wikipedia org w index php title Quench polish quench amp oldid 1195449933, wikipedia, wiki, book, books, library,
