Surface coatings for 3-piece freight bogie centre bearings

This research is conducted under Rail CRC Project 82 to investigate bogie rotation friction management. Existing centre bearing surfaces include flame hardened AlSl 1030 steel against un-greased Bisplate 320 steel, AlSl 1053 steel against un-greased Hadfield steel, and steel against polyethylene. The wear of the longitudinal rim wall of AlSl 1053 steel, Hadfield steel, and polyethylene centre bearing components is observed. The microhardness depth profile of an Hadfield steel centre bowl liner showed significant work hardening to 500 HV (100g) near the surface compared to 300 HV (100g) at the core. Plasma nitriding of steels with a low concentration of the strong nitride forming alloying elements such as aluminium, chromium, molybdenum, vanadium, and tungsten provides a surface hardness of around 500 HV (1009). This hardness is similar to that of the work hardened Hadfield steel, so when mated together should provide reasonable sliding wear resistance. Based on this reasoning, it is proposed that plasma nitrided Bisplate 320 molybdenum steel, that has a low concentration of the strong nitride forming alloying elements, could provide a candidate centre bearing surface when mated against work hardened Hadfield steel. Bisplate 320 molybdenum steel samples have been plasma nitrided at 450, 500, 550 and 580 C using 75% N2: 25% H2 mixture gas for 5 hours. The microhardness-depth profiles are presented. The optimum nitriding temperature for this steel was 500 C and it is the sample treated at this temperature that has been wear tested. Wear and friction testing of Hadfield steel pins against AlSl 1053, untreated and nitrided Bisplate 320 steel plate specimens, and polyethylene pins against Hadfield steel plate specimens was conducted using a tribometer in the pin-on-plate (reciprocating) mode. Prior to wear testing, the near surface hardness of the machined Hadfield steel pin was determined to be similar to the worn Hadfield steel centre bowl liner. However, after wear testing of the existing material pair, being Hadfield steel - AlSl 1053 steel, the work hardened case of the Hadfield pin had worn away and there was no further work hardening. This result shows that the current wear test method and conditions do not simulate the work hardening that occurs in Hadfield steel centre bowl liners in service. Therefore, this test is not considered suitable for the evaluation of material pairs for the centre bearing rim wall surfaces.

Media Info

  • Pagination: pp. 383-394
  • Monograph Title: Rail achieving growth: CORE 2006: conference on railway engineering, 30 April-3 May 2006, Melbourne, Victoria, Australia

Subject/Index Terms

Filing Info

  • Accession Number: 01517179
  • Record Type: Publication
  • Source Agency: ARRB
  • Files: ATRI
  • Created Date: Mar 4 2014 8:11PM