2.1. Materials and the Specimen Preparation

The experimental material is an aerial cold rolled 3039 superalloy sheet with 2 mm in thick. The chemical composition of GH3039 superalloy is shown in Table 1. Its ultimate stress and yield stress are 763 MPa and 520 MPa, respectively. The GH3039 superalloy fatigue specimens are cut by means of electric spark machining, which are presented in Figure 1. It should be noted that the length direction of all fatigue specimens is parallel to the rolling direction. Moreover, an arc of radius 19 mm of fatigue samples was machined after LSP. Fatigue specimens are divided into two groups: one is the as-received sample, and the other is laser treated sample. Each group contains six specimens. Before LSP, all samples were cleaned in acetone and then dried by hot-air.

(a) Dimensions of fatigue sample and (b) LSP sample.

The chemical composition of GH3039 superalloy (wt %).