No abstract

The AISI 52100 is a tool-type steel and is more often used in industry for the production of bearings. After the end of its life cycle, it is discarded or remelted, but both processes are considered expensive. Thus, the possibility of reusing this material through the powder metallurgy (PM) route is considered advantageous, since it transforms a waste into another product. To obtain the starting powders, the AISI 52100 steel scrap was submitted to a process of high energy ball milling, which was milled pure and with 1 and 3 % of niobium carbide (NbC) additions. Those additions were performed with the intention of increasing the milling efficiency of the steel, through formation of a metal-ceramic composite with a ductile-fragile behaviour. To determine the morphology and particle size, scanning electron microscopy (SEM) and particle size distribution tests were used. The results indicated that with the carbide addition, a significant increase in the milling efficiency was achieved, being possible to obtain nanoparticles after 20 hours of milling time.

In machining processes the chip is considered the disposal of no interest and so little analysis of the morphology observed as the types and forms submitted. The machining does not equal the composition of the physical properties of metal forming, it involves forces or active and inactive stocks. The combination of parameters, conditions and variables of the machining is a means of speculating and trying to explain the phenomena. Such actions reflect directly on the wear of tooling, and structural integrity. The experimental study of machining is of essential importance for the theory of plasticity can not explain satisfactorily the observed phenomena. The speed and the deformations are very large in the machining process, compared with those treated in this theory. This material may reveal why this chip segmented nature which are characterized by continuous large deformation in narrow bands between segments with little or no strain in their interiors. This is a very different from the continuous chip. With the aid of a tool in the expanding area of technology and scientific processing and analysis of images could provide a better analysis of the chips. The goal of this study was to relate the microstructure of the chips of superalloy Aluminum Bronze (C 63020) with milling parameters used in the process of turning on a CNC lathe Nardini - LOGIC 175, in order to analyze the behavior of even through a mechanical process.

In today's industry, production processes evolve every day, together with the development of new materials and geometries for tools and machines more accurate and efficient. These new technologies allow more flexible processes, such as replacement of the grinding process by turning of hardened materials. This change brings significant reductions in costs of tooling, setup time and machining.This work is a study of the conditions for turning aerospace alloy - Bronze Aluminum (UNS 63020)-hardened and tempered with a hardness of 35 HRC with carbide tools with positive and negative geometry.We analyzed the surface roughness of the specimen and as a criterion for end of life of the cutting tool was used to flank wear, crater wear, chip on the tool and/or the breach thereof.All the cutting parameters, when in their highest levels, do not contribute significantly to the reduction in tool life, while the surface roughness for the increase in the feed (f) and the cutting speed (vc) showed a greater influence on surface finish of the piece.