| 1. |
- Mallipeddi, Dinesh, 1987, et al.
(författare)
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Effect of running-in - load and speed - on surface characteristics of honed gears
- 2017
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Ingår i: World Tribology Conference 2017.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The initial cycles, as in a running-in process, can influence the performance of gear. Presented here are the surface characteristics of honed spur gears, which evolved due to the combined effect of running-in load (0.9 or 1.7GPa) and speed (0.5 or 8.3m/sec). The testing is performed using an FZG test rig. Running-in effected the surface layers to a depth of 5µm. High running-in load promoted plastic deformation of asperities, created microstructural changes associated with surface cracks and relaxed residual stresses. Surface phosphorus content from EP additives was also enhanced by higher running-in load. Interestingly, running-in speed promoted micropitting than load.
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| 2. |
- Mallipeddi, Dinesh, 1987, et al.
(författare)
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Influence of running-in on surface characteristics of efficiency tested ground gears
- 2017
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Ingår i: Tribology International. - : Elsevier BV. - 0301-679X .- 1879-2464. ; 115, s. 45-58
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Tidskriftsartikel (refereegranskat)abstract
- The effect of running-in load (0.9 or 1.7 GPa) on surface characteristics of ground spur gears, and on their development during subsequent efficiency testing (FZG rig), is examined. The effect was confined to less than 10 ism depth. Micropitting was associated with surface asperities and their plastic deformation; higher running-in load gave more micropitting, also after identical efficiency tests. Running-in increased unequal compressive residual stresses in both profile and axial directions, while after efficiency testing they approached equal levels. Deformation induced martensite is considered to form during running-in only at high load, still the amount after efficiency testing increased with running-in load. Higher surface content of phosphorous from extreme pressure additive (EP) occurred only after efficiency test following running-in at high load.
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| 3. |
- Yang, R., et al.
(författare)
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Effect of shot peening on the residual stress and mechanical behaviour of low-temperature and high-temperature annealed martensitic gear steel 18CrNiMo7-6
- 2017
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Ingår i: IOP Conference Series: Materials Science and Engineering. - 1757-8981 .- 1757-899X. ; 219:1, s. Art no: UNSP 012046-
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Konferensbidrag (refereegranskat)abstract
- A martensitic gear steel (18CrNiMo7-6) was annealed at 180 °C for 2h and at ∼ 750 °C for 1h to design two different starting microstructures for shot peening. One maintains the original as-transformed martensite while the other contains irregular-shaped sorbite together with ferrite. These two materials were shot peened using two different peening conditions. The softer sorbite + ferrite microstructure was shot peened using 0.6 mm conditioned cut steel shots at an average speed of 25 m/s in a conventional shot peening machine, while the harder tempered martensite steel was shot peened using 1.5 mm steel shots at a speed of 50 m/s in an in-house developed shot peening machine. The shot speeds in the conventional shot peening machine were measured using an in-house lidar set-up. The microstructure of each sample was characterized by optical and scanning electron microscopy, and the mechanical properties examined by microhardness and tensile testing. The residual stresses were measured using an Xstress 3000 G2R diffractometer equipped with a Cr Kα x-ray source. The correspondence between the residual stress profile and the gradient structure produced by shot peening, and the relationship between the microstructure and strength, are analyzed and discussed.
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