Formation of Nanostructure and Tool Wear during Cutting Treatment of Titanium Alloy

Methods of the optical metallography, TEM, SEM-technique, tests for hardness and wear resistance are used to investigated the structural - phase transformation in metal blanks from alloy VT23 at cutting treatment in an interval of speeds 2...120 m/min are given. The patterns of interaction of dynamic plastic deformation and destructions on macro-, meso-, micro-and nanolevels are determined. It is shown that the formation in metal blank of modulated high-tensile secondary nanostructures promotes a heightening of a protective wearproofity of treated metal blank, but cutting edge, lowering a wearproofity, of the cutting tool.

Microstructural Characterization and Mechanical Properties of Ti-6Al-4V Alloy Subjected to Dynamic Plastic Deformation Achieved by Multipass Hammer Forging with Different Forging Temperatures

Dynamic plastic deformation (DPD) achieved by multipass hammer forging is one of the most important metal forming operations to create the excellent materials properties. By using the integrated approaches of optical microscope and scanning electron microscope, the forging temperature effects on the multipass hammer forging process and the forged properties of Ti-6Al-4V alloy were evaluated and the forging samples were controlled with a total height reduction of 50% by multipass strikes from 925°C to 1025°C. The results indicate that the forging temperature has a significant effect on morphology and the volume fraction of primary α phase, and the microstructural homogeneity is enhanced after multipass hammer forging. The alloy slip possibility and strain rates could be improved by multipass strikes, but the marginal efficiency decreases with the increased forging temperature. Besides, a forging process with an initial forging temperature a bit above β transformation and finishing the forging a little below the β transformation is suggested to balance the forging deformation resistance and forged mechanical properties.

Improvement of Mechanical Properties and Morphological Studies of Friction Stir Processed Composites

Friction-stir processing (FSP) is a property enhancement technique which, not only removes the defects of initial casting process, but also improves the microstructure of the metals and metal matrix composites (MMCs). The process is based on frictional heating which results in a considerable dynamic plastic deformation within the metals. FSP can be specifically applied to develop fine-grained microstructures throughout the thickness of metal surface, to impart super plasticity and ensure homogeneous distribution of reinforced particles, if any. This chapter is a dedicated effort to consolidate the latest developments contributed by different researchers in last few years. The work covers various components and parameters, selected and used, for FSP to obtain specific desired results. Also, it includes past researches to exhibit various changes in mechanical properties with a keen focus on morphological study (by scanning electron microscopy) of these MMCs. In the last, a brief discussion on application and future scope of FSP processed MMC materials, is presented.

Analysis of Dynamic Plastic Deformation process on an Electrolytic Tough - Pitch copper (Cu-ETP): From material characterization to models improvement

This paper presents a comprehensive study of a direct impact compression loading on an Electrolytic Tough-Pitch copper (Cu-ETP). The aim of the study is to provide reliable experimental data in this dynamic loading using high-speed video camera records and real time projectile deceleration profiles. Test set-up has been optimized to ensure an efficient recovery of the samples after the Dynamic Plastic Deformation (DPD) process in the 103 to 104 s-1 strain rate range regime. Structural investigations have been made on post-mortem samples: microstructure investigations of recovered samples have shown more structural changes in terms of crystallographic texture and grain sizes. Post-mortem tensile tests have also been carried out to evaluate yield strength behavior of the Cu-ETP copper after the DPD process. Numerical simulations have been performed to evaluate the ability of empirical models to reproduce recorded signals. In-situ results (time evolution of strain, strain rate, temperature, etc.) given by the numerical analysis have contributed to enrich the post-mortem analysis.