Paper 4: Surface Integrity—A New Requirement for Surfaces Generated by Material-Removal Methods

1967 ◽  
Vol 182 (11) ◽  
pp. 31-45 ◽  
Author(s):  
J. F. Kahles ◽  
M. Field
Keyword(s):  
Residual Stress ◽  
Surface Layer ◽  
Fatigue Strength ◽  
Stress Corrosion ◽  
Surface Integrity ◽  
Material Removal ◽  
Electrical Discharge Machining ◽  
Electrochemical Machining ◽  
Practical Implementation ◽  
Surface Geometry

The design of structures for modern industry has created stringent service, reliability, and safety requirements. Present manufacturing specifications for surfaces are concerned primarily with geometry, which includes surface roughness and accuracy. The need is growing to consider not only surface geometry per se, but also the nature of alterations in the surface layer. Typical surface layer modifications, as a result of temperature, stress, and environment during material removal, include phase transformations, plastic deformation and fracture, and chemical changes. These various changes in the surface layer become increasingly significant with the more extensive application of materials such as high-temperature alloys, high-strength steels (including the maraging steels), refractory alloys, titanium, and beryllium. Some of the non-conventional machining methods, such as electrical discharge machining and grinding, electrochemical machining and grinding, and laser beam machining, can generate surface layer characteristics quite different from those produced by conventional methods. Surface alterations may also affect the residual stress, and with it the accuracy of thin section hardware, as well as decrease some of the significant mechanical and physical properties, such as fatigue strength, stress corrosion resistance, and fracture propagation rate. Control of surface layer characteristics, consistent with design requirements, develops ‘surface integrity’ which, in turn, leads to reliable service performance. A general review of previous work on the subject of surface integrity is presented. Typical microstructural surface alterations are illustrated, and the residual stress induced in the surface and its correlation with dimensional accuracy is demonstrated. A survey is presented relating machining methods to fatigue strength and stress corrosion characteristics. Finally, some guidelines are suggested for the practical implementation of surface integrity by means of processing specifications. Some consideration is given to the cost of implementing surface integrity requirements and their effect on production rates, including precautions concerning needless over-emphasis for certain manufacturing requirements. The data presented in this paper manifest that the metrologist's technical jurisdiction should be extended in depth from the Ångström range to the millimetre subsurface level.

Characterization of nanocrystalline surface layer induced by shot peening and effect on their fatigue strength.

2004 ◽  
Vol 843 ◽  
Author(s):  
Hideo Mano ◽  
Kondo Satoru ◽  
Akihito Matsumuro ◽  
Toru Imura
Keyword(s):  
Residual Stress ◽  
Surface Layer ◽  
Fatigue Strength ◽  
Vickers Hardness ◽  
Shot Peening ◽  
White Layer ◽  
The Other ◽  
Fatigue Properties ◽  
Nanocrystalline Layer

ABSTRACTThe shot peening process is known to produce a hard layer, known as the white layer” on the surface of coil springs. However, little is known about the fatigue properties of this white-layer.In this study, coil springs with a white-layer were manufactured. The surface of these springs was then examined using micro Vickers hardness, FE-SEM etc. to test fatigue strength of the springs.From the results obtained, a microstructure of the white-layer with grain size of 50–100 nm was observed, with a Vickers hardness rating of 8–10 GPa.Tow category springs were manufactured utilizing a double-peening process. These springs had the same residual stress destruction and surface roughness. Only one difference was observed: one spring had a nanocrystalline layer on the surface, while the other did not. The results of the fatigue test realized an increase in the fatigue life of the nanocrystalline surface layer by 9%.

Study on Surface Integrity of an Ultra-High Strength Alloy in HSC Process

2006 ◽  
Vol 532-533 ◽  
pp. 241-244
Author(s):  
Zhen Hai Long ◽  
Xi Bin Wang ◽  
Wen Xiang Zhao
Keyword(s):  
Residual Stress ◽  
Surface Layer ◽  
Surface Integrity ◽  
High Speed ◽  
High Strength ◽  
Cutting Parameters ◽  
Depth Of Cut ◽  
Cutting Condition ◽  
Tempered Martensite ◽  
Strength Alloy

Aiming to study the surface integrity of an ultra-high strength alloy in high speed milling process, 2K factorial design experiments were conducted to explore the effects of cutting parameters, such as cutting velocity, feed rate and depth of cut, on microstructure, microhardness and residual stress in the sub-surface layer. The following conclusions could be drawn from this paper within the range of cutting conditions: The cutting parameters could significantly influence the microstructure and microhardness in the surface and sub-surface layers, and the original fine martensite of the surface and sub-surface layer might be transformed into the over-tempered martensite, under-tempered martensite, secondary troostite, and tempered sorbite; Compressive residual stress distributions with different maximum stress values in the sub-surface layer of machined surfaces could emerge in high speed cutting process; the properly arranged cutting condition could achieve ideal surface characteristics and surface integrity.

scholarly journals Principles of the express method for controlling interelectrode space condition during wire electrochemical processing

2019 ◽  
Vol 9 (4) ◽  
pp. 269-280
Author(s):  
Vasyl Osypenko ◽  
Oleksandr Plakhotnyi ◽  
Oleksii Timchenko
Keyword(s):  
Electrical Discharge Machining ◽  
Electrochemical Machining ◽  
Practical Implementation ◽  
Movement Trajectory ◽  
Electrode Tool ◽  
Space Condition ◽  
Electrochemical Processing ◽  
Electrode Space ◽  
Anode Dissolution ◽  
Adaptive Adjustment

In the practical implementation of the sequential wire electrical discharge machining – pulsed electrochemical machining (WEDM – PECM) technology and in order to perform high quality electrochemical processing, there is a need for the real-time operational control of electrical parameters of inter-electrode space and corresponding adaptive correction of amplitude-frequency power supply parameters (AFPSP). In the context presented by the authors, a mathematical apparatus and an algorithm of operational galvanostatic mode monitoring of anode dissolution using wire electrode-tool are proposed. This will allow adaptive adjustment of AFPSP to ensure controlled passage of electrochemical reactions and significantly increase process stability, dissolved surface layer thickness uniformity along entire electrode tool movement trajectory and resulting surface quality.

scholarly journals Finite Element Analysis of Ball Burnishing on Ball-End Milled Surfaces Considering Their Original Topology and Residual Stress

Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 638 ◽  
Author(s):  
Cyrus Amini ◽  
Ramón Jerez-Mesa ◽  
J. Antonio Travieso-Rodriguez ◽  
Jordi Llumà ◽  
Aida Estevez-Urra
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Coefficient Of Friction ◽  
Surface Integrity ◽  
Finite Element Models ◽  
Real Surface ◽  
Ball Burnishing ◽  
Surface Geometry ◽  
Topological Features ◽  
The Coefficient Of Friction

Ball burnishing is a superfinishing operation whose objective is the enhancement of surface integrity of previously machined surfaces, hence its appropriateness to complement chip removal processes at the end of a production line. As a complex process involving plastic deformation, friction and three-dimensional interaction between solids, numerical solutions and finite element models have typically included a considerable amount of simplifications that represent the process partially. The aim of this paper is to develop a 3D numerical finite element model of the ball burnishing process including in the target workpiece real surface integrity descriptors resulting from a ball-end milled AISI 1038 surface. Specifically, its periodical topological features are used to generate the surface geometry and the residual stress tensor measured on a real workpiece is embedded in the target surface. Secondly, different models varying the effect of the coefficient of friction and the direction of application of burnishing passes with regards to the original milling direction are calculated. Results show that the resulting topology and residual stresses are independent of the burnishing direction. However, it is evident that the model outputs are highly influenced by the value of the coefficient of friction. A value of 0.15 should be implemented in order to obtain representative results through finite element models.

Analysis of Residual Stress Induced by Hand Grinding Process

2011 ◽  
Vol 681 ◽  
pp. 327-331 ◽  
Author(s):  
Sawsen Youssef ◽  
O. Calonne ◽  
Eric Feulvarch ◽  
P. Gilles ◽  
Hédi Hamdi
Keyword(s):  
Residual Stress ◽  
Experimental Study ◽  
Crack Initiation ◽  
Residual Stresses ◽  
Material Removal Rate ◽  
Surface Integrity ◽  
Material Removal ◽  
Removal Rate ◽  
Grinding Process ◽  
Cup Wheel

Grinding cup wheel is often used in the case of hand grinding which allows an important material removal rate but with secondary concern of surface integrity. Integrity is strongly affected by the process and consequently influences the surface behaviour in terms of resistivity to stress corrosion and crack initiation. This operation is difficult to master in terms of results on the surface and subsurface due to its manual nature. The paper presents results of an experimental study to investigate the residual stresses induced by this hand grinding process.

Nonconventional Machining Based on Electrical Charged Particles Motion in Liquid

2014 ◽  
Vol 657 ◽  
pp. 316-320
Author(s):  
Laurenţiu Slătineanu ◽  
Margareta Coteaţă ◽  
Irina Beşliu ◽  
Geo Caracaş ◽  
Gheorghe Bosoancă ◽  
...  
Keyword(s):  
Theoretical Analysis ◽  
Electrical Discharge ◽  
Material Removal ◽  
Electrical Discharge Machining ◽  
Charged Particles ◽  
Electrochemical Machining ◽  
Experimental Tests ◽  
Work Zone ◽  
The Common ◽  
Insulating Properties

<p class="TTPAbstract">Nonconventional machining methods are based on the transfer of the energy to the work zone in ways distinct from those applied in the case of the so-called classical machining methods. A group of nonconventional machining methods achieve material removal from workpiece by using the motion of the electrical charged particles in a liquid. Practically, some machining techniques included in the larger groups of electrical discharge machining and in electrochemical machining are based on the motion of electrical charged particles in fluid. The problem addressed in this paper is to identify the zones where differences between the two groups of machining methods appear. A theoretical analysis was developed in order to identify the common aspects and respectively the differences between the electrical discharge machining and electrochemical machining, if the machining liquid is considered. Some experimental tests were developed to highlight aspects specific to the above mentioned machining techniques. The research facilitated obtaining a more complete image of some common and distinct characteristics of electrical discharge machining and electrochemical machining. The significance of the electroconductive or insulating properties of the work liquid was highlighted.<o:p></o:p></p>

Influence of Microshot Peening on Surface Layer Characteristics of Cold Tool Steel

2007 ◽  
Vol 561-565 ◽  
pp. 897-900 ◽  
Author(s):  
Yasunori Harada ◽  
Kenzo Fukaura ◽  
Toshinori Aoki ◽  
Daien Yokoi ◽  
Yasushi Haruna
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Surface Layer ◽  
Fatigue Strength ◽  
Tool Steel ◽  
Compressive Residual Stress ◽  
Heating Furnace ◽  
Cemented Carbide ◽  
Compressed Air ◽  
New Type

Shot peening is a surface treatment and improves the performance of engineering components. More recently, a new type of microshot has been developed to enhance peening effect. In the present study, the influence of microshot peening on the surface layer characteristics of cold tool steel was investigated. In the experiment, the microshot peening apparatus with a heating furnace was produced experimentally. The projective method of the microshot was a compressed air type. The peening microshots of 0.1mm diameter were cemented carbide and the workpiece was commercially cold tool steel SKD11. Surface roughness, compressive residual stress, and hardness in the peened workpiece were measured. The effect of microshot peening on the fatigue strength of cold tool steel was also examined. The use of hard microshot such as cemented carbide was found to cause a significantly enhanced peening effect for cold tool steel.

Effect of impregnated powder materials on surface integrity aspects of Inconel 625 during electrical discharge machining

2016 ◽  
Vol 232 (7) ◽  
pp. 1259-1272 ◽  
Author(s):  
Gangadharudu Talla ◽  
Soumya Gangopadhyay ◽  
CK Biswas
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Surface Integrity ◽  
Electrical Discharge ◽  
Electrical Discharge Machining ◽  
Machining Process ◽  
Inconel 625 ◽  
Powder Materials ◽  
Powder Concentration ◽  
Pulse On Time

In recent times, nickel-based super alloys are widely utilized in aviation, processing, and marine industries owing to their supreme ability to retain the mechanical properties at elevated temperature in combination with remarkable resistance to corrosion. Some of the properties of these alloys such as low thermal conductivity, strain hardening tendency, chemical affinity, and presence of hard and abrasives phases in the microstructure render these materials very difficult-to-cut using conventional machining processes. In this work, an experimental setup was developed and integrated with the existing electrical discharge machining system for carrying out powder-mixed electrical discharge machining process for Inconel 625. The experiments were planned and conducted by varying five different variables, that is, powder concentration, peak current, pulse-on time, duty cycle, and gap voltage based on the central composite design of response surface methodology. Effects of these parameters along with powder concentration were investigated on various surface integrity aspects including surface morphology, surface roughness, surface microhardness, change in the composition of the machined surface, and residual stress. Results clearly indicated that addition of powder to dielectric has significantly improved surface integrity compared to pure dielectric. Among the powders used, silicon has resulted in highest microhardness, that is, almost 14% more than graphite. Lowest surface roughness (approximately 50% less than pure kerosene) and least residual stress were obtained using silicon powder (approximately 8% less than graphite-mixed dielectric). Relative content of nickel was reduced at the expense of Nb and Mo after addition of powders like aluminum and graphite in dielectric during electrical discharge machining.

Research on Stress Corrosion Behavior of AISI304 Stainless Steel Enhanced by Ultrasonic Peening Treatment

2011 ◽  
Vol 697-698 ◽  
pp. 404-408 ◽  
Author(s):  
D.Q. Yin ◽  
Dong Po Wang
Keyword(s):  
Residual Stress ◽  
Stainless Steel ◽  
Surface Layer ◽  
Stress Corrosion ◽  
Corrosion Test ◽  
Base Material ◽  
Magnesium Chloride Solution ◽  
Cracking Behavior ◽  
Ultrasonic Peening ◽  
Stress Corrosion Test

Surface-strengthening treatment was performed on the welded joints and base material specimens of AISI304 austenitic stainless steel using ultrasonic peening treatment. Stress-corrosion test in a 42% boiling magnesium chloride solution were conducted with treated and untreated specimens. Four-point loaded specimens were employed in the stress-corrosion test. Residual stress in the surface layer of the specimens was analyzed with an x-ray stress analyzer before the stress corrosion test. The microstructure of the specimens was observed by a scanning electron microscope after the stress corrosion test. The state of stress in the surface layer of the specimens affected by the ultrasonic peening treatment was analyzed. The stress corrosion cracking behavior was studied by observing the corrosion fractographs. The results showed that the stress corrosion resistance of the welded joint and base material specimens was remarkably improved because of the compressive residual stress employed by the ultrasonic peening treatment. Fracture modes were of the same kinds in the treated and untreated specimens.

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