Analysis of the Influence of Shot Peening on the Fatigue Life of a Hard Chromium Electroplated AISI 4340 Steel Underplate

Author:  Torres, Baptista, Nascimento, Voorwald
Source:  Conf Proc: ICSP-9 (pg 273-279)
Doc ID:  2005097
Year of Publication:  2005
Abstract:  
ABSTRACT Hard chromium plating is widely used on AISI 4340 landing gears to obtain high levels of resistance against wear and corrosion. However, it causes a reduction in the fatigue strength of the components. In order to increase the fatigue resistance of chromium electroplated steel, a shot peening treatment was applied before coating deposition. This treatment introduces compressive residual stresses in the coating / substrate interface in order to make more difficult the crack propagation from the chromium plating into the base material. In the present research, the effect of shot peening in fatigue life of AISI 4340 steel, tempered to the two different hardnesses used in landing gear, is evaluated by rotating bending fatigue tests. To support the fatigue result analyses, the compressive residual stress fields were measured by x-ray tensometry, prior and after fatigue tests in order to analyze its relaxation. In addition, the surfaces of fractured fatigue specimens were investigated.