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Austenitic stainless steel E309L is frequently used for welded repairs on 13%Cr-4%Ni martensitic stainless steel blade runners. However, very high tensile residual stresses are found in the upper layers of these repairs, thus reducing the fatigue resistance of the repaired area in comparison with the free of residual stress base material. The use of hammer peening to increase the fatigue life of E309L welded on UNS-S41500 base metal plates has been investigated using welded samples replicating in situ blade runner repairs. Residual stress measurements using the contour method on these samples have confirmed the high stresses caused by flux cored arc welding (FCAW) of E309L, leaving stress magnitudes close to the ultimate tensile strength of the base material. Hammer peening of the surface beads effectively creates high compressive stresses at the weld’s surface up to 3 mm depth. Alternating bending fatigue tests conducted on hammer peened samples have shown an average life increase of 5.8 times at S a = 330 MPa over unpeened samples. Fatigue tests have however shown diminishing returns when overpeening the samples. [ABSTRACT FROM AUTHOR]

Highlights: [•] Induction heating is used to introduce residual stresses (RS) in hollow fatigue specimens. [•] The effect of RS on fatigue life of AISI 304L stainless steel is investigated. [•] A statistical method is used to assess the validity of the experimental results. [•] RS evolution during the tests is shown to affect significantly the fatigue life. [•] Life prediction based on stabilized RS correlates well with nonzero mean stress fatigue tests. [Copyright &y& Elsevier]

The austenitic stainless steel E309L filler is a commonly used material for in-situ crack repairs of hydro-turbines due to its high weldability, mechanical and chemical compatibility with the turbine's base material. However, experimental data for the as-welded E309L filler is scarce. In this paper, the mechanical properties of as-deposited 75% Ar/25% CO 2 flux-cored arc welding E309L austenitic stainless steel are investigated. The material is shown to be rate- and temperature-sensitive. Furthermore, although the directional nature of the welding/repair process might suggests otherwise, the response is found to be isotropic. Finally, a classic three-dimension Johnson-Cook plasticity theory is implemented and reproduces the experimental results with good accuracy. [ABSTRACT FROM AUTHOR]