A4T - Politecnico di Milano

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Open points at the begin of the project • Corrosion fatigue crack growth in A1N Material is affected by the coalescence phenomena; • The corrosion fatigue SN diagram for A1N material seems continuously decreasing N cycles • The damaged surface shows corrosion pits and cracks Dipartimento di meccanica [MPa] 500 400 300 200 100 S-N A1N, provino lucidato, testato a fine vita (pH6) Batch 1, provino lucidato, testato a fine vita (pH6) Batch 2, provino lucidato, testato a fine vita (pH6) Log. (A1N e Batch 1-2 (pH6)) 1.E+05 1.E+06 1.E+07 1.E+08 Full scale tests RSSB project 2
Wolaxim experimental plan and aims Small scale tests • To consolidate the corrosion-fatigue SN diagram for the material A1N, but also to investigate the corrosion fatigue life of A4T and 30CrMb. • To evaluate the effect of the corrosion on the crack propagation rate • To study the coelescence phenomena and its interaction with the growth of the cracks • To understand the mechanism of pit-to-crack transition To set a corrosion fatigue model for the life prediction of railway axles Full scale tests • To investigate scale effect on the process of corrosion fatigue surface damage • To validate the corrosion fatigue model Dipartimento di meccanica 3
Page 1: Wolaxim final meeting 24 th -25 th
Page 5 and 6: Materials 5 30CrMb Bainitic microst
Page 7 and 8: Summary of A1N tests • End life t
Page 9 and 10: Summary of A4T tests • End life t
Page 11 and 12: Tests on 30CrMb material For 30CrMb
Page 13 and 14: Observations • Atmospheric corros
Page 15 and 16: Corrosion fatigue process 15 Dipart
Page 17 and 18: First stage of the Fatigue Life 180
Page 19 and 20: Damage of the surface 19 • Chemic
Page 21 and 22: Probability 0.99 0.96 0.90 0.75 0.5
Page 23 and 24: Probability 0.99 0.96 0.90 0.75 0.5
Page 25 and 26: Crack propagation tests Microdrille
Page 27 and 28: Interrupted test and crack propagat
Page 29 and 30: Crack growth rate A4T 320 MPa Confr
Page 31 and 32: Propagation of single cracks A4T 40
Page 33 and 34: Interrupted test and crack propagat
Page 35 and 36: Prove Full-Scale
Page 37 and 38: Full scale test A4T = 360 MPa Stop
Page 39 and 40: Plastic replica 1e6 cicli 0° Dipar
Page 41 and 42: Plastic replica 2.2e6 cicli 0° Dip
Page 43 and 44: Mechanical cleaning- 4.317e6 cycles
Page 45 and 46: Full scale test A4T = 240 MPa Stop
Page 47 and 48: Plastic replica 2e6 cycles Dipartim
Page 49 and 50: TWI Digital Microscope - 2e6 cycles
Page 51 and 52: TWI Digital Microscope - 2e6 cycles
Page 53 and 54:
Assile 038 - Replica 6e6 cicli Dipa
Page 55:
Conclusion • Agreement between cr
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A4T - Politecnico di Milano

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