OPTIMIZATION OF PROPERTIES OF POWDERED IRON AND STAINLESS-STEEL PARTS BY STATISTICAL DESIGN AND COMPUTER ANALYSIS *

Abstract

A statistically designed experiment was formulated to study the effect of several major powder variables on the strength properties of porous iron and stainless-steel parts. The resulting data were analysed by means of a suitable computer programme to develop individual response equations relating the chosen dependent variables with selected independent variables. Computer analysis of the data and the optimization techniques adopted led to an improvement of ∼50% in the strength of sintered parts by comparison with those made by conventional processes. A certain set of powder properties and process variables resulted in a tensile strength of 170 MN/m², 11.5% elongation, and very low dimensional change in a sintered iron sample with 25% porosity. In a 316L stainless-steel part with 25% porosity, a tensile strength of 435 MN/m², 0.2% yield strength of 269 MN/m², and 12.6% elongation were reached–values far above those that can be obtained without the benefit of statistical design.

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