Têmpera por Indução Eletromagnética Progressiva de Alta Frequência Aplicada em Virabrequim de Motocicleta

Abstract

Mechanical properties of machined components are controlled by inducing phase transformations in the outer layer of the materials. Induction hardening is a manufacturing process where the surface hardness is enhanced while the core retains its original structure and characteristics. This work aims to apply the electromagnetic induction heat treatment to the crankshaft of a motorcycle, focusing on surface hardening. The heat treatment was applied in the motorcycle manufacturing industry. Metallographic tests, optical microscopy, X-ray diffraction (XRD), and hardness tests (Rockwell C - HRC and microhardness - HV) were performed. The results show that the hardening depth reached 1.5 mm, with average microhardness values of 678.2 HV, 516.2 HV, and 658.8 HV for the three tested samples. The resulting microstructure in the core shows pro-eutectoid ferrite network around the grains of toostite pearlite, while the thermally treated region is composed of a refined area of carbides dispersed in a refined ferrite-rich matrix, resulting in a tempered-martensite microstructure responsible for the high hardness observed.