Wyniki wyszukiwania - BazTech

1

Effect of surface integrity on fatigue life of 7075‑T6 aluminum alloy by combination of fine turning with hydrostatic deep rolling

Zhou Yongxin, Chu Xingrong, Zang Shunlai, Sun Jiao, Yang Lei, Gao Jun

Archives of Civil and Mechanical Engineering

|

2023

|

Vol. 23, no. 1

art. no. e41, 2023

EN

In this study, the 7075-T6 aluminum alloy sample was firstly prepared by fine turning(FT) process, and then the surface treatments were subjected to hydrostatic deep rolling(HDR), including constant pressure deep rolling(CPDR) and increasing pressure deep rolling(IPDR). Subsequently, the influence of surface integrity on the fatigue life of the 7075-T6 aluminum alloy is investigated by the combination of FT with HDR. The results show that the fatigue life of IPDR and CPDR samples is increased significantly by 148% and 450% compared to the FT sample in the tensile-compression fatigue test. The improved fatigue life of IPDR and CPDR samples is a result of reduced significantly surface roughness and the increase of surface compressive residual stress, surface micro-hardness and the depth of plastic deformation layer. In addition, the deeper plastic deformation layer is the main reason for the higher fatigue life of the CPDR sample than the IPDR sample.

2

The influence of the tool surface texture on friction and the surface layers properties of formed component

Šugárová Jana, Šugár Peter, Frnčík Martin, Necpal Martin, Moravčíková Jana, Kusý Martin

Advances in Science and Technology. Research Journal

|

2018

|

Vol. 12, no 1

181--193

EN

The morphological texturing of forming tool surfaces has a high potential to reduce friction and tool wear and also has an impact on the surface layers properties of formed material. In order to understand the effect of different types of tool textures, produced by nanosecond fibre laser, on the tribological conditions at the interface tool-formed material and on the integrity of formed part surface layers, the series of experimental investigations have been carried out. The coefficient of friction for different texture parameters (individual feature shape, including the depth profile of the cavities and orientation of the features relative to the material flow) was evaluated via a Ring Test and the surface layers integrity of the formed material (surface roughness and subsurface micro hardness) was also experimentally analysed. The results showed a positive effect of surface texturing on the friction coefficients and the strain hardening of test samples material. Application of surface texture consisting of dimple-like depressions arranged in radial layout contributed to the most significant friction reduction of about 40%. On the other hand, this surface texture contributed to the increase of surface roughness parameters, Ra parameter increased from 0.49 μm to 2.19 μm and the Rz parameter increased from 0.99 μm to 16.79 μm.

3

Surface microhardening studies on steels after high feed milling

Petrů Jana, Zlámal Tomáš, Špalek František, Čep Robert

Advances in Science and Technology. Research Journal

|

2018

|

Vol. 12, no 2

222--230

EN

The paper deals with the impact of high-speed machining production methods on the integrity of component surfaces. One has to point out that cutting conditions during machining have a significant impact on the final properties of surface and subsurface layers of the workpiece. The conclusion summarizes and analyzes the achieved results of experimental activities on stainless austenitic steel 1.4301, hardened tool steel 1.2343 and high-speed steel 1. 3344 (ASP 2023). The results of the work experimental parts demonstrate the influence of cutting parameters on selected surface integrity ones, specifically strengthening the surface and subsurface layers. The performed experiments show that microhardness of a surface layer of the machined material can be influenced by suitable cutting conditions and other cutting process parameters.

4

Technological parameters of belt grinding process of hard steel

Hamdi A., Aliouane T., Bouzid D.

Mechanics and Mechanical Engineering

|

2017

|

Vol. 21, nr 4

843--853

EN

A mechanical workpiece in the field of the automobile industry (crankshaft, camshaft, valves, gear, synchronizer gearbox ... etc) is good quality, if it fulfills the function for which, it is destined. To ensure the required function of these workpieces, they are necessary for the purpose of machining a high precision superfinishing process. There are several methods of superfinishing in this area, for example: honing, polishing, belt grinding ... etc. The belt grinding is a mechanical manufacturing process by removing of material involving a tool called abrasive belt. It is complementary to the hard turning and recent compared to other process principle and objective. To date the cutting mechanism and its exact effect on the surface integrity remains unclear. This study allows optimizing the technological parameters, such as time of belt grinding, size of the abrasive grains, the rotation speed and lubrication, and seeing the influence of these parameters on the surface state of the hard steel.

5

Effects of cryogenic cooling on surface layer characteristics produced by hard turning

Grzesik W., Żak K., Prażmowski M., Storch B., Pałka T.

Archives of Materials Science and Engineering

|

2012

|

Vol. 54, nr 1

6-12

EN

Purpose: The purpose of this research is to test the applicability of cryogenic hard machining for improving surface integrity produced in turning operations on parts made of high-strength, low alloy 41Cr4 steel with hardness of 57š2 HRC. The aim of the research is to quantify the surface roughness and the mechanical properties of the sublayer produced under practical working conditions. Design/methodology/approach: The objectives were achieved by the characterization of machined surfaces using 2D and 3D scanning techniques. The surface profile and surface topographies were characterized and compared for optimal machining conditions. Moreover, microhardness beneath the surface was measured using a hardness tester with a Berkovich indenter. The microstucture of the sublayer was examined using SEM/EDS technique. Findings: This investigation confirms that hard machining allows producing surfaces with acceptable surface roughness and, in some cases, with attractive service properties. The main conclusion is that cryogenic hard cutting operations can partly eliminate grinding operations in cases when white layer is not produced. Research limitations/implications: The basic limitations concern the measurement of residual stresses and microstructural alterations including phase analysis. Another important problem is to optimize the surface integrity including surface roughness and sublayer properties. Practical implications: One practical outcome is selecting the machining conditions which guarantee the demanded surface finish together with bearing properties. Moreover, they should be selected in terms of desired microhardness distribution. Originality/value: Original value of the paper is the presentation of the effects of cryogenic pre-cooling of the workpiece in hard turning operations. Experiments were performed under the conditions combining low surface roughness with attractive service properties. This knowledge can support the design of technological processes of hard steel parts.

6

Functional properties of hardened steel parts generated by turning and ball burnishing operations

Grzesik W.

Advances in Manufacturing Science and Technology

|

2012

|

Vol. 36, nr 4

5-17

EN

This paper presents the experimental results of the role of ball burnishing in improving of the surface integrity produced in finish hard machining of hardened 41Cr4 steel. The characterization of the surface integrity includes two standardized sets of 2D and 3D roughness parameters, the distributions of microhardness, residual stresses and the microstucture of the sublayer which was examined using SEM/EDS technique. The functional properties of the surface layer were predicted and discussed. This study reveals that ball burnishing performed on hard turned surfaces improves not only surface roughness but also results in better service properties compared with those generated by CBN hard turning.

PL

W artykule przedstawiono analizę wyników doświadczalnych dotyczących roli nagniatania tocznego kulką ceramiczną w polepszeniu właściwości warstwy wierzchniej wytworzonej podczas wykończeniowego toczenia utwardzonej stali 41Cr4. Charakteryzacja wytworzonej warstwy wierzchniej obejmuje określenie dwóch zbiorów znormalizowanych parametrów chropowatości powierzchni, rozkład wartości twardości naprężeń własnych oraz badania mikrostruktury metodami mikroskopii elektronowej EM/BSE/EDX. Analiza wyników badań pozwala stwierdzić, że nagniatanie kulką po toczeniu na twardo poprawia nie tylko chropowatość powierzchni, ale również polepsza właściwości eksploatacyjne w porównaniu z efektami toczenia narzędziami z CBN.

7

Characteristics of surface integrity generated by oblique machining of steel parts

Grzesik W.

Advances in Manufacturing Science and Technology

|

2012

|

Vol. 36, nr 3

5-18

EN

In this study the surface integrity produced by oblique turning of a C45 carbon steel was quantified by means of 2D and 3D surface roughness parameters, strain-hardening effects and associated residual stresses. Surfaces were produced by a special straight-edged cutting tool with large inclination angle of 55 degrees equipped with carbide cutting tool inserts. It was documented that oblique machining performed with relatively higher feed rate allows to obtain lower surface roughness and, in general, better bearing characteristics. Moreover, compressive stresses with the maximum value located close to the machined surface and with parabolic profile can be induced into the surface layer. The magnitude of stresses depends on the strain-hardening rate of the surface layer.

PL

W pracy scharakteryzowano stan technologicznej warstwy wierzchniej wytworzonej w ukośnym toczeniu stali C45. Stosowano kryteria parametrów chropowatości powierzchni 2D i 3D, efektu umocnienia odkształceniowego i naprężeń własnych. Powierzchnie kształtowano specjalnym narzędziem z węglików spiekanych, w którym prostoliniowa krawędź skrawająca ma duży kąt pochylenia 55 stopni. Analiza wyników badań pozwala stwierdzić, że ukośne skrawanie prowadzone z dużą wartością posuwu pozwala uzyskać powierzchnię o mniejszej chropowatości i lepszej nośności. Dodatkowo w warstwie wierzchniej są wytworzone ściskające naprężenia własne o maksymalnej wartości w pobliżu powierzchni i profilu parabolicznym. Wartość maksymalna naprężeń ściskających zależy od stopnia umocnienia odkształceniowego materiału warstwy wierzchniej.