Digital Repository, ECF14, Cracow 2002

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Fatigue Crack Growth in Re-welded AISI 4130 High Strength Steel

Last modified: 2013-02-10


All over the world the flight safety has been the main concerns ofaeronautical authorities. Structural failures during flight are usually attributed to fatigue ofmaterials, project errors or aerodynamic overloads. Nowadays, fatigue is the mostimportant consideration of project and operation in both civil and military aircrafts. Fromsmall aircraft (<20 kN) the most solicited component is one that support the motor. Thiscomponent contains a complex geometry, made of different welded tubes from severalangles. It has the function of supporting the aircraft motor, besides maintaining fixed thenose landing gear in another extremity. As a result, fatigue cracks are always observed atthe weld sites. After successive welding repairs, they are frequently retired of operation.Therefore, it is extremely important to determine the effects of welding repairs on thestructural integrity of this component. The aim of this study is to analyze the effects ofsuccessive TIG welding repairs on the structural integrity of the AISI 4130 aeronauticalsteel through fatigue crack propagation tests located in base material, heat affected zone -HAZ - and weld metal (the original one and that re-worked). Increase of the fatigue crackpropagation was observed in both HAZ and re-welded material. The results wereassociated to their microhardness and microstructure variation.

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