Laser cladding process to enhanced surface properties of hot press forming die: A review

Laser cladding is one of the advance processes in laser surface treatments. The process involved a laser beam to combines another material that has different metallurgical properties on a substrate, whereby a very thin layer of the substrate has to be melted for it to achieve metallurgical bonding with minimal dilution of added material and substrate. The resulted properties were characterized by surface topography, subsurface microstructure, hardness, and residual stresses. The objective of this paper is to review the factors that affected of cladding process to get the best cladding, suitable to enhance hot press forming die surface and subsurface. The parameter control, metallurgical bonding between coating and substrate, and effect of powder size were discussed

Optimization of laser melting parameter to enhanced surface properties in hot press forming die

This paper presents laser melting process with various parameter to enhanced surface properties of AISI H13 tool steel. The design of experiment (DOE) optimisation was conducted to obtain significant model using regression analysis. DOE were analysed using response surface method (RSM) with Box-Behnken design approach. Design Expert 7 software was used to design parameter of laser melting process. The laser melting processes was conducted using Nd:YAG laser system with pulsed mode at a constant average power of 100 W, overlapping rate of 30 to 50%, peak power of 1700 to 2500 W and pulse repetition frequency (PRF) of 50 to 70 Hz respectively. The responses were characterised for sub-surface hardness, melt depth and surface roughness. The results show that optimum parameter of 2500 W peak power, 60 Hz PRF and 30% overlapping rate produced highest surface hardness of 793.7 HV0.1 with 0.21 mm melted depth and 3.89 µm surface roughness from experimental data. This finding was important to enhance properties of AISI H13 tool steel for hot press forming die using laser process

Surface Modification of AISI H13 Tool Steel by Laser Cladding with NiTi Powder

This paper presents laser cladding of NiTi powder on AISI H13 tool steel surface for surface properties enhancement. The cladding process was conducted using Rofin DC-015 diffusion-cooled CO2 laser system with wavelength of 10.6 µm. NiTi powder was pre-placed on H13 tool steel surface. The laser beam was focused with a spot size of 90 µm on the sample surface. Laser parameters were set to 1515 and 1138 W peak power, 18 and 24 % duty cycle and 2300–3500 Hz laser pulse repetition frequency. Hardness properties of the modified layer were characterized by Wilson Hardness tester. Metallographic study and chemical composition were conducted using field emission scanning electron microscope and energy-dispersive X-ray spectrometer (EDXS) analysis. Results showed that hardness of NiTi clad layer increased three times that of the substrate material. The EDXS analysis detected NiTi phase presence in the modified layer up to 9.8 wt%. The metallographic study shows high metallurgical bonding between substrate and modified layer. These findings are significant to both increased hardness and erosion resistance of high-wear-resistant components and elongating their lifetime

Effect of heating time on hardness properties of laser clad gray cast iron surface

This paper presents effect of heating time on cladded gray cast iron. In this study, the effect of heating time on cladded gray cast iron and melted gray cast iron were analysed. The gray cast iron sample were added with mixed Mo-Cr powder using laser cladding technique. The mixed Mo and Cr powder was pre-placed on gray cast iron surface. Modified layer were sectioned using diamond blade cutter and polish using SiC abrasive paper before heated. Sample was heated in furnace for 15, 30 and 45 minutes at 650 °C and cool down in room temperature. Metallographic study was conduct using inverted microscope while surface hardness properties were tested using Wilson hardness test with Vickers scale. Results for metallographic study showed graphite flakes within matrix of pearlite. The surface hardness for modified layer decreased when increased heating time process. These findings are significant to structure stability of laser cladded gray cast iron with different heating times

Laser melting of groove defect repair on high thermal conductivity steel (HTCS-150)

This paper presents laser melting repair of groove defect on HTCS-150 surface using Nd:YAG laser system. Laser melting process was conducted using JK300HPS Nd:YAG twin lamp laser source with 1064 nm wavelength and pulsed mode. The parameters are pulse repetition frequency (PRF) that is set from 70 to 100 Hz, average power (PA) of 50–70 W, and laser spot size of 0.7 mm. HTCS-150 samples were prepared with groove dimension of 0.3 mm width and depths of 0.5 mm using EDM wire cut. Groove defect repaired using laser melting process on groove surface area with various parameters’ process. The melted surface within the groove was characterized for subsurface hardness profile, roughness, phase identification, chemical composition, and metallographic study. The roughness analysis indicates high PRF at large spot size caused high surface roughness and low surface hardness. Grain refinement of repaired layer was analyzed within the groove as a result of rapid heating and cooling. The hardness properties of modified HTCS inside the groove and the bulk surface increased two times from as received HTCS due to grain refinement which is in agreement with Hall–Petch equation. These findings are significant to parameter design of die repair for optimum surface integrity and potential for repairing crack depth and width of less than 0.5 and 0.3 mm, respectively