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ACTA AERONAUTICAET ASTRONAUTICA SINICA ›› 2020, Vol. 41 ›› Issue (8): 223631-223631.doi: 10.7527/S1000-6893.2020.23631

• Solid Mechanics and Vehicle Conceptual Design • Previous Articles     Next Articles

Damage mechanism of shot peened ultra-high strength steel under combined action of marine environment and fatigue load

TAN Xiaoming, ZHANG Danfeng, ZHAN Guipan, WANG De   

  1. Qingdao Branch of Naval Aeronautical University, Qingdao 266041, China
  • Received:2019-11-03 Revised:2020-01-06 Online:2020-08-15 Published:2020-02-21

Abstract: The landing gear structure of carrier-based aircraft is subject to not only erosion by marine atmosphere, salt spray and sea wave splashes, but also large ejection take off and arresting landing load. Under the combined action of marine environment and fatigue load, the bearing capacity of ultra-high strength steel landing gear structure is significantly deteriorated, posing a serious challenge to its safe use. Based on the marine environment in which the carrier-based aircraft is in service, corrosion fatigue tests were conducted on two kinds of test specimens of ultra-high strength steel: shot peened and unpeened. The variation rule of fatigue life was obtained. Through the analysis of roughness, grain size, micro-hardness, residual stress and fatigue fracture, the action mechanism of shot peening on fatigue life enhancement, the mechanism of alternate action of corrosion and fatigue damage and the mechanism of pre-corrosion fatigue damage were revealed. The results show an average increase of 93.1% in fatigue life after shot peening. For the shot peened specimen, a slight pitting with a depth of about 20 μm results in a fatigue life decay of about 30%. A competition mechanism exists between shot peening and corrosion. The damage mechanism of alternating corrosion and fatigue has a considerably more serious effect on the service life of the ultra-high strength steel than the pre-corrosion fatigue damage mechanism. Under the same conditions, the fatigue life of the former is only 47%-54% of that of the latter.

Key words: ultra-high strength steel, marine environment, shot peening, corrosion, fatigue life, damage mechanism

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