Abstract
Laser surface transformation hardening (LSTH) of AISI 4130 was investigated by a Nd:YAG pulsed laser. Laser focal height (LFH), pulse width (LPW), scanning speed (LSS), and power (LP) varied during the experiments. The microstructure of the treated zone was characterized by optical (OM) and field emission scanning electron microscopy (FESEM). Micro-hardness was measured in the width and depth directions. Results showed that the hardness and depth of hardened layer increased by decreasing the LSS and the laser focal position (LFP), and by increasing the LPW. The results were compared with those obtained by furnace heat treatment of the same steel. Eventually, a finite element model was employed for the simulation of the LSTH of AISI 4130 steel and calculation of the heat-treated zone. The results showed that the model can predict with accuracy the temperature profile and the size and the shape of the laser hardened region.
Highlights
Surface transformation hardening processes are developed to produce wear, corrosion, and fatigue-resistant surfaces in order to enhance the lifespan for numerous industrial applications.There are several methods in order to improve surface properties
For the CO2 laser surface hardening samples, the results showed that melting of the surface layer occurred
The results showed that the micro-hardness increased from 242 HV to 1700 HV and the depth of the hardened layer was in the 60–80 μm range
Summary
Surface transformation hardening processes are developed to produce wear-, corrosion-, and fatigue-resistant surfaces in order to enhance the lifespan for numerous industrial applications. Dumiterscu et al [8] investigated the fiber laser surface heat treatment of AISI D2 steel. The advantages of this process were (1) catastrophic fracture of the used carbide tools could be removed, (2) tool life was improved, (3) chatter of machining and formation of saw tooth chips could be prevented, and (4). Guarino et al [17] improved the fatigue life of AISI 1040 steel by a high-power diode laser treatment. Yazici et al [21] investigated the effect of different processing temperatures on wear properties of R260 grade rail steel They studied the mechanical properties, surface hardness, tribological properties, and microstructure of high-power diode laser treated specimens. The effects of laser focal point position, laser pulse width, and LSS were investigated after LSTH of AISI 4130 alloy steel. The results show that the model can predict with accuracy the temperature profile and the size and the shape of the laser hardened region
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