Application of statistics models to verify the influence of residual elements (Cr, Ni e Cu) in the machinability of free cutting steels

by Nascimento Sousa, Marcelo do

Abstract (Summary)
Low carbon free-cutting steels are widely used for parts and components subject tomoderate strength levels and relatively low shock loading, with machinability being the mostimportant factor. Examples are hydraulic valves, keys, contact boards and other parts requiringrapid metal removal. These materials are especially designed for high machinability, that is,reduced tool-chip contact length, low coefficient of friction between the tool and the chip or theworkpiece, production of easy handled chips, low cutting forces and power consumption, therebyproviding long tool lives and/or high productivity by using high cutting speeds. Elements like Mn,P, S and Pb are generally present in their composition ensuring improved machinability.However, low carbon free-cutting steels also contain residual elements that often impairmachinability such as Cr, Ni, Mo and Cu, which are difficult to be eliminated during themanufacturing process. This work investigates the influence of the trump elements Cr, Ni and Cuon the machinability of the SAE 12L14 low carbon free-cutting steel after testing in accordancewith VOLVO STD 1018, 712 standard. The standard is based on tool life tests using HSS singlepoint tools in face milling operation under special cutting conditions. The tool life results weretreated statistically using ANOVA method, Student´s t distribution and multiple regressionanalysis. The results showed that the residual elements actually affect machinability of the SAE12L14 low carbon free-cutting steel, with Ni and Cu being more significant.
This document abstract is also available in Portuguese.
Bibliographical Information:

Advisor:Álisson Rocha Machado; Márcio Bacci da Silva; Marcos Antonio de Souza Barrozo; Joao Roberto Ferreira

School:Universidade Federal de Uberlândia

School Location:Brazil

Source Type:Master's Thesis

Keywords:Usinabilidade Low carbon free-cutting steels Machinability Trump elements Design of experiments and statistic analysis Volvo STD 1018 - 712 standard


Date of Publication:02/21/2006

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