Discrete spot laser hardening and remelting with a high-brilliance source for surface structuring of a hypereutectoid steel

作者：Tricarico L; Ancona A; Palumbo G^*; Sorgente D; Spina R; Lugara P M

来源：Materials and Design, 2017, 115: 194-202.

DOI：10.1016/j.matdes.2016.10.079

• Laser hardening
• Laser remelting
• Surface structuring
• Finite element model tuning

In this work the single-pulse laser irradiation of a hypereutectoid steel was investigated using a fiber laser source, in a range of process parameters enabling surface hardening and remelting. Effects of laser power, pulse energy and defocusing distance were investigated using a numerical/experimental approach. Laser surface treatments were conducted on uncoated samples without any gas shielding, changing both the laser power and the pulse energy, and exploring a wide range of defocusing distances. Numerical simulations were conducted using a finite element model calibrated by means of an optimization procedure based on a specific calculation algorithm and using a subset of experimental data producing surface melting. Using both simulations and experiments, the process operating windows of the discrete spot laser treatment were determined: it was found that, when varying the laser power between 250 W and 750 W, melt-free hardened zones are produced with a maximum extension between 0.7 mm and 1.0 mm; on the contrary, in case of more tightly beam focusing conditions, surface melting occurred with a size of the re-melted areas ranging between 1.0 mm and 1.4 mm. Results further showed that a small change (generally 2-3 mm) of the defocusing distance suddenly brings the material from melting to a non-hardening condition.

• 出版日期2017-2-5