An Experimental Investigation Of Various Factors On The Machinability Of Powder Metallurgy Austenitic Stainless Steels

The machinability of powder metallurgy steels is poorer compared with wrought steels of appropriate composition and/or mechanical [properties. The reason for it is a larger number of material and processing variables affecting the final properties of a sintered material. Therefore the machining of powder metallurgy (PM) steels is a permanent subject of investigation and practice. The aim of the book is to make on the basis of present knowledge an overview of all interacting factors in machining process including those applied for the improvement of the machinability. There are the properties of basic plain iron and alloyed powders, various additions, compaction and sintering conditions. Effect of porosity, individual alloying elements and microstructure character is considered. The description of the basic machining processes with their characteristics and with the characteristics of the tool geometry belongs to the mentioned factors. For the improvement of machinability of PM steels different machining aids, as S, MnS, MoS2 and other are frequently used and their chemical and physical characteristics are given. The effect of various machining aids used on machinability of sintered plain iron, iron-carbon and of steels alloyed with Cu, Ni, Mo, Cr, Mn including powder forged steels with very different mechanical properties and very different microstructures is analysed and summarized. The high-speed steel, hardmetal and other tools with their geometry as the part of the cutting process are described in relation to the sintered powder materials. The recommendations for machining of various steels enclose the present knowledge about the machinability of powder metallurgy steels.

Stainless steels represent a quite interesting material family, both from a scientific and commercial point of view, following to their excellent combination in terms of strength and ductility together with corrosion resistance. Thanks to such properties, stainless steels have been indispensable for the technological progress during the last century and their annual consumption increased faster than other materials. They find application in all these fields requiring good corrosion resistance together with ability to be worked into complex geometries. Despite to their diffusion as a consolidated materials, many research fields are active regarding the possibility to increase stainless steels mechanical properties and corrosion resistance by grain refinement or by alloying by interstitial elements. At the same time innovations are coming from the manufacturing process of such a family of materials, also including the possibility to manufacture them starting from metals powder for 3D printing. The Special Issue scope embraces interdisciplinary work covering physical metallurgy and processes, reporting about experimental and theoretical progress concerning microstructural evolution during processing, microstructure-properties relations, applications including automotive, energy and structural.