Surface grain coarsening and surface softening during machining of ultra-fine grained titanium

Abstract

Experiments are run to show that different machining conditions applied to ultra-fine grained pure titanium lead to different levels of grain coarsening and softening near the machined surface. Under “hard” machining conditions the upper 40 microns of the machined surface are altered with a decreased microhardness. The experimental results are reasonably reproduced by model calculations. Expanding the parameter field of the model calculations, the surface coarsening diagram and the surface softening diagram due to machining are presented, showing the region of technological parameters, under which neither grain coarsening nor softening takes place along the machined surface

Properties and Performance of Ultrafine Grained Titanium for Biomedical Applications

“…The UFG material keeps the advantages of cpTi concerning corrosion resistance, biocompatibility and osseointegration and, at the same time, achieves strength levels comparable to those of Ti alloys thanks to the use of the SPD (Severe Plastic Deformation), Figure 10, for grain refinement [3][4][5][6][51][52][53][54][55][56][57][58][59] .…”

“…One of the most successful processing routes for grain size reduction is a special mechanical work called SPD (severe plastic deformation) which is described elsewhere 8,17,54,[60][61][62][63][64] . The method also known as Equal-Channel Angular Pressing (ECAP) 5,6,8,51,60,64 .…”

“…SPD processing of cpTi is an effective way to produce an UFG structure 51,54,60,[65][66][67][68] . Figure 10a shows a TEM micrograph of UFG Ti obtained by ECAP-Conform with equiaxed morphology with grain/subgrain sizes between 150 and 200 nm.…”

Physical Principles of Manufacturing of Periodic Profile Bars by Vibratory Drawing

“…Однако коэффициент использования металла по этой технологии не превышает 0,05 -0,14 [1 -4]. Заготовки периодических профилей так же можно получать асимметрической прокаткой металлических порошков с последую щей механической обработкой [5,6].…”

“…Для идеально пластического материала при отсутствии конвекции это уравнение запишется следующим образом: (6) Учитывая, что деформации малы, т. е. то Поскольку 7то получаем волновое уравнение (8) где ρ -плотность материала деформируемой системы.…”