Papers by Author: Renato Panelli

Abstract: Tool steels have important participation in the worldwide market of steels. They are used by metal-mechanical industry as cutting tools, molds, punches, etc. Because the use is of great responsibility, it is important to discuss the relationship between microstructure and mechanical properties. The starting material was powder of a commercial tool steel with the composition (wt%) 2.5%C, 5.25%Cr, 0.9%Si, 9.75%V, 0.5Mn, 1.3%Mo and balance Fe. The samples were obtained by hot isostatic pressing (hip) process, and than were austenitizing at 1120°C and submitted to tempering in the temperature range varying from 430° to 550°C. The aim of this work was to evaluate the correlation between heat treatment, microstructure and mechanical properties. Results of toughness and hardness are presented.

Abstract: The two major working characteristics of the oil control ring are: 1) to scrape the lubricant oil from the cylinder wall to the direction of the crankcase, and 2) to maintain a sufficient amount of lubricant oil to the compression rings above it in order to sustain a suitable lubricant film thickness between the rings and the cylinder. The oil control ring efficiency is the outcome of the combination of the following parameters: conformability, sort of the contact between the ring and the cylinder, contact pressure, and oil scraping dynamics. This work shows the development of an original oil control ring named Monoland, conceived by powder metallurgy design, having high conformability and optimized contact pressure that provides a superior oil scraping efficiency even with decreasing the friction losses. These qualities were achieved as an effect of an extensive product advance program established by Mahle Metal Leve Research and Development Center and Mahle Metal Leve Miba Sinterizados, which involved steps beginning from the product concept to the production streamline and passing through an extensive product validation program.