| Inconel 718 alloy is widely used to make some key components of aerospace engines and gas turbines. In liquid hydrogen rocket engine, the hydrogen embrittlement sensitivity of Inconel 718 alloy is a serious problem in the aging state, which can be resolved by laser surface treatment of Inconel 718 alloy. However, the reports on the laser surface treatment of Inconel 718 alloy are fewer, particularly the studies of relationship between its microstructure and properties about cycles of laser irradiation have not been reported. In view of this, the surface of Inconel 718 alloy is treated by using self-developed laser surface treatment testing machine in oder to study the relationship between its microstructure and cycles of laser irradiation.In this paper, a series of laser surface treatment experiments of Inconel 718 alloy are carried by using self-developed laser surface treatment device, which includes the laser surface treatment experiments under different heat treatment processes and the ones under the different cycles. Based on these experiments, the effect of laser surface treatment on its microstructure and properties is investigated by using modern analytical tools, such as optical metallographic analysis, scanning electron microscopy (SEM) analysis, X-ray analysis, hardness analysis and so on.The experiment results show that plastic deformation occurs on the surface of the Inconel 718 alloy samples, forms obvious slip bands, twins and grain relief formed after laser surface treatment. Inconel 718 alloy containing a great dealδphases, laser surface treatment contributes to the dissolution and conglomeration ofδphase. Nanocrystalline structures are obtained on the surface of the Inconel 718 alloy via heat treatment process A(954℃×1h) and laser surface treatment(Tm=750℃,f=1/10Hz,N=1000cycles), and residual stress occurs in the surface of Inconel 718 alloy. Except heat treatment process A, Inconel 718 alloy exhibits the cyclic softening characteristics after laser surface treatment. |
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