M. E. Alvarado Ponce, D. M. Lopez Ochoa, L. G. Vargas Quiroz, National University of Colombia, Medellin, Colombia
In an induction heating process, the control signal is a square pulse train with a specific frequency, the spectral content of this signal is accomplished by odd harmonics. Based on the SHE- PWM (Selective Harmonic Eimination - Pulse Width Modulation) method for designing pulse trains, it is possible to remove specifically the 3rd, 5th, 7th, 9th, and 11th harmonic. The aim of this work is to evaluate the resulting effect of selective elimination of harmonics on microhardness and microstructure at different depths from surface after an induction process on an AISI 1050 steel. This effect is analyzing as a non-linear superposition of single phenomenon each one with a specific power and depth hardening. The tests were planned based on experimental design using frequency as main factor. Optical and scanning electron microscopy images were used to assess the microstructure and to support the results obtained by microhardness tests.
Summary: This work is a result of development of an experimental induction furnance designed and constructed for academic purpose at Physical Engineering program with colaboration of the Surface and Tribology Group of the National University of Colombia (Medellin). The design of the inverter for the furnace have flexibility for manipulate control variables, operating point, and different process like hardenning surface.
The harmonic problem is consider an important point of the art of state in the develop of induction heating process.
