Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
APPLICATION OF MICROWAVE HYBRID HEATING FOR PACK CHROMIZING OF THE AISI M2 TOOL STEEL
Submission Author:
Vitor Silveira Rolin , SP , Brazil
Co-Authors:
Vitor Silveira Rolin, Luciana Takahashi, Juno Gallego
Presenter: Vitor Silveira Rolin
doi://10.26678/ABCM.COBEM2023.COB2023-0513
Abstract
Failures caused by wear and corrosion can greatly shorten the life of engineering tools and parts. A solution to reduce these failures is the strengthening of surfaces by thermochemical treatments, such as pack chromizing. That treatment demands high temperatures and a long processing time, causing a high energy and time cost. Modern metallurgical processing claims more efficient and sustainable heating techniques, becoming microwave heating an innovative and promising process. In the present work a domestic microwave oven, operated at 2.45 GHz and with nominal power of 1050 W, was applied for pack chromizing of the AISI M2 tool steel samples performed at 1000C during 1 hour. High temperatures was obtained by hybrid heating mechanism, where an thermal insulated silicon carbide ring acting as susceptor was able to transfer heat to the samples. Pack chromizing samples were prepared insert small pieces of AISI M2 steel (5 x 5 x 20mm) into a powder mixture composed by Cr-rich iron alloy acting as diffusion metal, ammonium chloride (NH4Cl) as activator and aluminum oxide (Al2O3) as inert compound. Temperature was measured by K-type thermocouple. After air cooling samples were investigated by optical and scanning electron microscopy, EDS microanalysis, X-ray diffraction (XRD) and Vickers microhardness. The innovative treatment was able to form hard chromium-rich coatings on the surface of AISI M2 steel samples, which average thickness was 6.9 µm. Microstructure analysis have shown that coatings are composed by 2 distinctive layers, formed due to partition during diffusion of the chromium from mixture with the iron and carbon from the steel. XRD results show that outer layer is mainly composed by Cr2C0.46N0.44 orthorhombic chromium carbonitride and few body-centered cubic ferrite. Vickers microhardness of the chomized surfaces has attained 1480±156HV, near 3.7 times harder than substrate/matrix. The obtained results confirm that microwave hybrid heating is a faster e quite promising metallurgical process to improve surface properties for tool steels.
Keywords
coating, pack chromizing, microwave hybrid heating
