Abstract
Reliable and resilient constructions are basic for ensuring the safety of various structures. The superalloys are used as constructive materials due to their superb mechanical properties and endurance. However, even these materials can have certain areas where the stress concentration is higher than expected, such as drilling holes, which are common in various structures that need additional enhancement. Surface laser modifications of the areas surrounding the holes drilled in Nimonic 263 sheets are done by pulsed picosecond and nanosecond Nd:YAG laser irradiations with pulse durations of 170 ps and ≤8 ns, respectively. Following the laser surface treatment, the effectiveness of the enhancement was analyzed by the microhardness test and the deformation test. The results show that the deformation and stress values are decreased by 25−40 percent, showing the improvement in the resilience to deformation. The Vickers microhardness test results indicate an improvement in the Nimonic 263 microhardness. The dimensions of the microcracks are higher for the untreated material in comparison to the laser-treated material.
Highlights
The areas around the holes on the sheets are treated with laser irradiation in order to strengthen the material around the drilled holes, in terms of reinforcing the location where the stress concentration is expected
Nanosecond laser processing of the material results in uniform modification, with laser spots overlapping in order to homogenize the laser beam energy distribution on the surface
After picosecond laser processing of the material outside the hole, the surface morphology appears uniform throughout the area affected by the laser light, with approximately 1.5 mm width around the hole
Summary
The nickel-based superalloy studied in this work is the Nimonic 263, a centered cubic austenite crystal structure alloy with superb surface stability, high corrosion and oxidation resistance, thanks to the aluminum and chromium present in the alloy, high mechanical strength, excellent flexible properties, which makes it convenient for both hot and cold working processes, as well as good weldability and formability, compared to other nickelbased alloys [7]. These properties give Nimonic 263 a wide use in marine and gas turbine engines, combustion chambers for aeronautical use, etc. Various laser surface treatments are of great importance [14], such as laser polishing [15,16] of surface hardening [17], surface cladding [18], and thermal spraying [19,20,21]
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