Influence Of Surface Integrity Research Articles

Influence of surface integrity on the fatigue performance of TiB2/Al composite treated by ultrasonic deep rolling: Experiments and simulations

The influences of surface integrity on the fatigue performance of in-situ 6 wt% TiB2/2024Al composite treated by ultrasonic deep rolling (UDR) were comprehensively investigated with both experiments and simulations. Results reveal that only a single pass of UDR treatment can impressively reduce the surface roughness of the fine-turned specimens by 94 %. Moreover, axial compressive residual stress (RSc) larger than −400 MPa and strain hardening (SH) higher than 50 % were obtained on the surface. The comprehensive effect of these surface integrity improvements has enhanced the fatigue limit by 22 %, extended the fatigue life by 10∼20 times, and expanded the safe region in the Goodman-Haigh graph by 14.6 %. More importantly, UDR significantly dispersed the TiB2-particle aggregates in the composite surface, which provided the possibility of improving the surface comprehensive mechanical properties of particles reinforced metal matrix composites (PRMMCs) through a simple and convenient mechanical way.

Surface integrity and fatigue performance of GH4169 superalloy using abrasive belt grinding

GH4169 superalloy is the key material for advanced aero-engine high-temperature blades. Improving the surface integrity of the GH4169 superalloy after machining is conducive to improving fatigue performance, which is of great significance for the long-term stable service of the aero-engine. Abrasive belt grinding can effectively improve the surface integrity of GH4169, but the influence of surface integrity on fatigue performance after belt grinding with different process parameters has not been fully revealed. The grinding experiments on the influence of different process parameters on GH4169 surface integrity were carried out, and the influence of process parameters on surface morphology, roughness, and residual stress was explored. On this basis, fatigue experiments were carried out on the samples processed with typical process parameters at 80 % yield strength. The influence of process parameters on fatigue performance was discussed in combination with the surface integrity and cross-section of four groups of samples. The results show that different abrasive belt grinding process parameters can significantly change the surface morphology, roughness, residual stress, and other surface integrity indexes. Roughness mainly affects stress concentration. Macroscopically, the greater the roughness is, the easier crack initiation is. Sample 3 with the smallest roughness is 111.04 % higher than Sample 1. The residual stress can inhibit crack initiation and slow crack propagation. Even under large roughness, the fatigue life of Sample 4 is still better than that of Sample 1, and the stable propagation rate of Sample 4 is 32.4 % slower than that of Sample 3. Considering the anti-fatigue performance and processing efficiency, the linear speed range is 11 to 15 m/s, the feed speed range is 5 to 9 mm/s, and the grinding depth is 0.1 to 0.25 mm.

Influence of Surface Integrity and Coating on the High Cycle Fatigue Properties of 300M Steel from Self-Heating Tests under Cyclic Loads

300M, an ultra-high strength steel used in aeronautics for landing gears, is generally shot-peened and coated with High Velocity Oxygen Fuel sprayed WC-10Co-4Cr to improve tribological behavior. In literature, few treatment parameters have been tested to analyze the surface integrity influence on fatigue properties. The self-heating method under cyclic loading is used to quickly determine fatigue properties by coupling them with intrinsic dissipation. Investigations on dissipation mechanisms of coating and substrate enable to develop self-heating models. That is the first step to build a lifespan forecast model based on temperature measurement to study shot-peening and coating influence on fatigue properties.

Influence of surface integrity on fatigue life of bearing rings finished by precision hard turning and grinding

Machined surface integrity of bearing rings is often the main concern for the bearing manufacturers as it affects their fatigue life. The present study investigates the surface integrity of AISI 52100 bearing rings finished by precision hard turning and grinding and its influence on fatigue life. A twin-disk machine is used to evaluate the RCF life. As main results, precision hard turning can achieve low surface roughness 0.1 μm Ra with respect to the required 0.2 μm Ra obtained by grinding. Both processes introduce microstructural changes. At subsurface, precision hard turning induces subsurface compressive and maximum residual stresses at 10–50 μm depth, corresponding to the transition zone formed after a thin white layer (<1 μm); however, grinding induces tensile residual stresses from 15 μm depth, corresponding to the bulk material. The residual stresses measured during RCF test (after running-in process and after spalling) of ground ring specimens exhibit peak compressive value in subsurface from 140 μm depth. The ring specimens machined by precision hard turning have fatigue life four times higher than those machined by grinding. This enhancement of RCF life is due to the low roughness reached and also to the subsurface compressive residual stresses at shallow depth before RCF test.

Influence of Surface Integrity after Turning on the Consecutive Plasma Nitridation and Barkhausen Noise Emission

This paper deals with non destructive evaluation of components after plasma nitridation via Barkhausen noise techniques. The effect of the different surface state before plasma nitriding is studied via non destructive Barkhausen noise technique as well as the conventional destructive techniques. Turning operation was performed by the use of the inserts of variable flank wear. The results of experiments show that Barkhausen noise emission is a function of tool flank as well as the different regime of heat treatment. The different state of the surface before plasma nitriding results into the different thickness of compound layer. Furthermore, also the underlying diffusion layer state differs.

Influence of surface integrity on vibration characteristics of microbeams

Abstract This is the first study on the influence of the surface integrity on the vibration characteristics of microbeams. A new model that represents the real surface texture of beams is developed. This model incorporates measures for the surface roughness, surface waviness, altered layer, and surface excess energy. This model outweighs Gurtin-Murdoch surface model by representing beams with real engineering surfaces. The derived model is solved for the free vibration of simple-supported, cantilever, and clamped-clamped microbeams. A parametric study is carried out to demonstrate the variations of the natural frequencies of microbeams due to surface integrity and a beam size decrease. It was revealed that a decrease in the beam size is accompanied with an increase in the surface integrity effects. Moreover, the surface integrity may decrease/increase the beam natural frequency. Surface integrity either softens the beam and hence decreases its natural frequency or inhibits the vibration propagation through the beam and hence increases the beam frequency.

Influence of surface integrity on the plastic flow in analogous testing of 42CrMo4

Surface modification of workpieces for cold forming processes is common in industrial practice. Specific surface topographies manufactured by means of shot peening form lubricant pockets, which provide a continuous lubricating film throughout the process. Furthermore, hydrostatic as well as hydrodynamic lubrication effects emerge, which further reduce the friction during the process and protect the tool from wear effects. These effects are well researched and applied in order to enable cold forming processes. In dry forming processes, no lubricants are used, and the positive lubrication effects do not appear. Surface modifications by shot peening or knurling change surface integrity in terms of hardness, residual stresses and geometry. The effects of the changed surface integrity on the forming process are not researched. In tribometer tests, a hard and rough surface texture lead to a lower frictional shear stress, whereas a rather smooth and hard surface texture leads to a lower punch force in an extrusion process. The mechanisms between surface textures and the smoothing and forming process are unknown. Furthermore, findings of the tribometer tests cannot be fully transferred to the extrusion process. As in tribometer tests a pin is used as tool and in extrusion a whole die, a discrepancy between the most suitable surface texture for a friction reduction results out of different flow conditions. Still, the tribometer tests give a first reference on a surface pretreament. The paper deals with an investigation of surface textures in order to distinguish characteristics of surface textures respectively a friction reduction. By means of indentation tests of the quenched and tempered steel 42CrMo4 the plastic flow in dependency of different surface integrities are researched. The results show which characteristics help to lower the punch force the most, so for further investigations an optimized surface modification is set up in order to enable a dry metal forming process.

Influence of surface integrity on the fatigue behaviour of a hot-forged and shot-peened C70 steel component

Hot-forging is a process commonly used in the manufacturing of automobile parts such as connecting rods. Most hot-forged components are shot-blasted after forging in order to clean off the forging scale. The shot-blasting process is akin to shot-peening and greatly affects the surface integrity of the components by introducing hardening and residual stresses. This study focuses on the influence of the surface integrity on the fatigue behaviour of a hot-forged C70 steel connecting rod. Specimens were machined out of the connecting rods in order to perform fatigue testing on the forged surface. Several surfaces states, including shot-peened surfaces, were studied in order to quantify the influence of the surface integrity.A thorough characterisation of the surface integrity of the specimens was first performed. The hardness, residual stresses and microstructure gradients were analysed, and the surface of each specimen was scanned using a profilometer. The specimens show complex networks of surface defects introduced during forging, and the shot-blasting process introduces important surface residual stress and microstructure gradients. High cycle fatigue tests in plane bending were then performed on the specimens, with the surface scans helping to identify the critical defect on which crack initiation occurred. The fatigue results, presented in the form of a Kitagawa diagram, are analysed in order to determine which surface integrity parameters are the most influential on fatigue behaviour. The forging defects have an important negative effect on fatigue strength. After shot-blasting, the fatigue strength increases considerably because of the large compressive residual stresses introduced by the shot-blasting process.

Special Issue on Machining of CFRP Composites

There is a growing need for carbon-fiber-reinforced plastics (CFRP/CFRTP/GFRP) inthe aircraft, aerospace, and automotive industries due to their high strength-to-weightratio, high rigidity, and other features. Using these outstanding composites as machinecomponents requires machining with the desired configuration, accuracy, and surfaceintegrity. However, due to the composite structure of high-strength carbon fiber and theadhesive plastics, CFRP is difficult to machine without causing spalling or delamination,fluffing, fiber pullout, thermal degradation of the matrix resin, or other kinds of surfaceor subsurface damage. Rapid tool wear is also a serious problem that varies with thefiber orientation of the CFRP. In order to avoid these problems, various innovative or careful approaches have beentaken in drilling, trimming by milling, sawing, and grinding CFRP. Non-traditional machiningtechniques, including the use of abrasive waterjets, have been employed. Inthese techniques, the machining process, tool geometry, cooling system, and other machiningparameters are optimized. In addition, the influence of surface integrity on thetensile and/or fatigue strength or on other mechanical properties of CFRP has also drawninterest. In addition, regarded as a “machining process” in a broad sense, the press formingof continuous fiber reinforced thermoplastic (CFRTP) sheets is a promising techniqueused in the manufacture of structural components. In CFRTP forming, the effects thatfiber layout naturally have on the deformation mechanisms must be understood, andtemperature, pressure, speed, and stroke control should be optimized. This special issue consists of twelve recent, high-quality research articles related to themachining of CFRP composite materials. These articles include one review and eleventechnical papers on the topics of drilling, end milling, abrasive waterjet machining, andforming. The editors would like to express our deep appreciation to all the authors fortheir invaluable submissions and to the anonymous reviewers for their earnest efforts.Without these, this special issue could not have been published. We hope that furtherresearch on the machining of CFRP composites will make advances inspired by thisspecial issue.

Influence of Milling on the Fatigue Lifetime of a Ti6Al4V Titanium Alloy

The present article focuses on the influence of machining on the fatigue life of a titanium alloy: Ti6Al4V. An experimental design was adopted in order to highlight the effects of machining parameters on surface integrity while generating very different surfaces with a view to subsequent fatigue testing (four point bending tests). Firstly, the impact of machining parameters on surface integrity was demonstrated. Then, the influence of surface integrity on fatigue lifetime was observed: no influence of the geometric and metallurgical parameters was observed. However, the mechanical parameter (e.g., residual stress) seemed to have a preponderant influence. To conclude, a machining plan of procedure was proposed to significantly improve the fatigue lifetime as compared with a reference industrial plan of procedure.

P090 ステンレス鋼の研削加工におけるクーラント中の不純物が加工面性状に及ぼす影響(メカボケーション学生研究発表セッション)

P090 ステンレス鋼の研削加工におけるクーラント中の不純物が加工面性状に及ぼす影響(メカボケーション学生研究発表セッション)

Influence of Surface Integrity in Silicon Wafer Thickness Measurements by Reflection Spectroscopy

Wafer thickness meter by reflection spectroscopy is used for on-site thickness inspections in wafer thinning process, because of its excellent properties as high measurement accuracy in very thin wafers inspections by non-contact sensing. In practice, ground surfaces are not ideal flat surfaces. Thus the spectra suffers influences of the surface roughness and the waviness, as modifying spectral features by optical diffusion, and as decreasing the reflection received by dispersion of propagating directivity. In this paper, we investigate how the surface integrities of ground wafer surfaces are involved in the thickness measurements by both theoretical and experimental approach, to investigate the requirements in sample conditions and to guarantee the accuracy of the measurements.

Influence of Surface Integrity on the Tribological Performance of Cold Forging Tools

In forming industry the tool is fundamental for the profitability, as it determines efficiency of cold forging process. In this regard, the tool surface has a distinctive influence on the tribological conditions and thus on the occurring tool stresses. The present study investigates the influence of different fine machining strategies on the tribological performance of cold forging tools made of WC-Co cemented carbide by applying the double cup extrusion test.The results reveal that a peened surface causes higher friction in the forming process compared to polished tool surfaces up to 100%. For polishing a minimum in friction is found for the diamond grit D 6μm with a friction factor of m = 0.03.

Influence of surface integrity on bonding process

Adhesive bonding technology is successfully applied partly in the primary production, partly in the renovation in various fields of human activities. This fact emphasizes the importance of the partial factors research, which influence is essential for the quality, reliability and necessarily the usable life of bonded joints. The mechanical preparation of bonded surface is a varied process which influences directly the resultant bonded joint quality. The aim of the bonded surface mechanical preparation is the adhesion improvement in the adhesive &amp;ndash; adherend interface. For mechanical preparation we use tools of defined cutting edge, by means of which we get the uniform surface texture, e.g. by milling. On the contrary such methods are more often used when the uniform surface cannot be reached. Shot blasting and grinding are significant representatives of these methods. The manual grinding can be significantly applied mainly in the agriculture. The absence of connected areas availability for the mechanical tooling and impossibility of their work clamping are the reasons for that. The breakwater in the sprinkler cistern restricting the liquid motion is the example.

Influence of surface integrity on fatigue strength of 40CrNi2Si2MoVA steel

Influence of surface integrity (including surface roughness, residual stresses, and microstructure in surface) on fatigue limit of 40CrNi2Si2MoVA steel specimens is investigated comprehensively in this work according to a systematic consideration. The surface integrity of specimens is changed due to several widely used manufacturing procedures: heat-treatment, grinding, electro-polishing, hard chromium plating and shot peening. In comparison with specimen electro-polished after grinding, the specimen without polishing has 10% lower fatigue limit due to higher surface roughness; while shot peening improves the fatigue limit for about 36% due to inducing of compressive residual stress field in the surface and transferring the fatigue crack source from surface to interior. The fatigue limit of specimen with decarburized layer after grinding is lower about 13%, but the shot peening can eliminate its detrimental effect. Hard chromium plating decreases the fatigue limit dramatically. The shot peening carried before plating can improve the fatigue limit of specimen and cause it to get to a level even higher than that of specimen without plating.

2309 ADI 歯車の負荷能力に関する研究 : 表面性状が限界伝達荷重に及ぼす影響

2309 ADI 歯車の負荷能力に関する研究 : 表面性状が限界伝達荷重に及ぼす影響

Influence of surface integrity on performance of coated cutting tools

The paper reports on the mechanisms taking place in varying the surface integrity of cermet substrates and their influences on coating adhesion as well as wear behaviour of new developed coated tools. The coating technique used in these tests is plasma assisted chemical vapor deposition (PACVD). Variations of surface integrity were done by grinding operations as well as using a water peening device. Topics considered are the relations between the surface properties of the substrate and the performance of the coated tools. Investigations are done by the use of scratch tests and machinability tests. Face milling experiments were carried out in terms of performance and wear behaviour of these tools.