Pre PVD-Coating Processes and their Effect on Substrate Residual Stress in Carbide Cutting Tools

2010 ◽  
Vol 438 ◽  
pp. 17-22 ◽  
Author(s):  
Berend Denkena ◽  
Bernd Breidenstein
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Cutting Tools ◽  
Residual Stress State ◽  
Pvd Coating ◽  
Parameter Variations ◽  
Single Process ◽  
The Stability ◽  
Cohesive Damage ◽  
Coated Cemented Carbide

Cohesive damage of PVD-coated cemented carbide cutting tools is ascribed to the residual stress state of the substrate subsurface. The present paper shows the formation of the substrate residual stress in the process chain as well as the stability of the single process steps referred to the scattering of the residual stress values. Depth resolved residual stress measurements across coating and substrate subsurface show a layer in the substrate, where possibly tensile stress occurs, from where cohesive damage may be initialized during tool use. Results of experiments are presented, where the influence of parameter variations in pre coating processes on the residual stress state is investigated. The characteristics of compressive residual substrate stress during the final PVD-process is presented as well as a correlation between coating and substrate stress.

Residual Stress Gradients in PVD-Coated Carbide Cutting Tools

2006 ◽  
Vol 524-525 ◽  
pp. 607-612 ◽  
Author(s):  
Berend Denkena ◽  
Bernd Breidenstein
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Cutting Tools ◽  
Surface Residual Stress ◽  
Vector Method ◽  
Near Surface ◽  
Residual Stress State ◽  
Coated Tools ◽  
Cohesive Damage ◽  
Coated Carbide

PVD-coated cutting tools show a typical kind of failure in use: cohesive damage, which is believed to be a result of the residual stress state of substrate and coating. As the sin2ψ-technique does not give satisfactory information on near surface residual stress trends of coated tools the scattering vector method was applied to determine residual stress depth distributions of coating and substrate. The results are presented and an attempt for an interpretation is given.

Residual Stress in PVD-Coated Carbide Cutting Inserts - Applications of the sin2ψ and the Scattering Vector Method

2010 ◽  
Vol 638-642 ◽  
pp. 2383-2388 ◽  
Author(s):  
Berend Denkena ◽  
Georg Erkens ◽  
Bernd Breidenstein
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Cutting Tools ◽  
X Ray Diffraction ◽  
Vector Method ◽  
Residual Stress State ◽  
Coated Tool ◽  
Cutting Inserts ◽  
Cohesive Damage ◽  
Coated Carbide

Premature collapse in terms of cohesive damage of PVD-coated carbide cutting tools often results in a time and cost consuming immediate interrupt of the cutting process. It is assumed that the residual stress state of the composite coating – substrate in combination with external loads during tool use is responsible for cohesive damage. The X-ray diffraction methods sin2 and scattering vector are applied for determination of the residual stress depth distribution in the coating and the substrate’s subsurface. Investigations of the residual stress state of commercial PVD-coated carbide cutting tools are presented. It is determined to what extent the single process steps during tool manufacturing are responsible for the final residual stress state of the PVD-coated tool. Furthermore the meaning of the PVD-coating process for the substrate’s residual stress state is investigated. Moreover, possibilities of controlling the residual stress state of the substrate by changing process variables of selected process steps are analyzed.

Residual Stress Development in Laser Machined PVD-Coated Carbide Cutting Tools

2013 ◽  
Vol 768-769 ◽  
pp. 391-397 ◽  
Author(s):  
Bernd Breidenstein ◽  
Christoph Gey ◽  
Berend Denkena
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Cutting Tool ◽  
Cutting Tools ◽  
Machining Process ◽  
Laser Machining ◽  
Residual Stress State ◽  
Stress States ◽  
The Individual ◽  
Coated Carbide

Abstract. There is growing interest in laser machining as an alternative to abrasive processes for creating cutting tool micro geometries. This technology is also suitable for creating micro geometries on cutting edges of superhard cutting tools. The pulsed nanosecond lasers, which are commonly used for this type of application, induce a high thermal load in the tool. This heat is believed to result in tensile residual stresses at the cutting edge surface, which are generally unfavorable for cutting tool performance because of the tendency to crack formation and propagation. Different levels of compressive residual stress exist after each step (sintering, grinding, shot peening, etching and PVD-coating). From investigations of commercial processes for manufacturing PVD-coated carbide cutting tools it is known that the final residual stress state of the carbide subsurface is a result of superposition of the stress states resulting from the individual process steps. In contrast to that, a laser machining process is expected to produce tensile residual stress due to the heat input. The present work describes the influence of a process chain alteration for PVD-coated carbide cutting tools by a laser machining process on the residual stress state in the finished tools.

scholarly journals Influence of Steel Grain Size on Residual Stress in Grinding Processing

2010 ◽  
Vol 638-642 ◽  
pp. 2389-2394 ◽  
Author(s):  
Masahide Gotoh ◽  
Katsuhiro Seki ◽  
M. Shozu ◽  
Hajime Hirose ◽  
Toshihiko Sasaki
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Grain Size ◽  
Stress State ◽  
Mechanical Grinding ◽  
Fine Grained ◽  
Residual Stress State ◽  
Analysis Methods ◽  
Average Grain Size ◽  
Fine Grained Steels

The fine-grained rolling steels NFG600 and the conventional usual rolling steels SM490 were processed by sand paper polishing and mechanical grinding to compare the residual stress generated after processing. The average grain size of NFG600 and SM490 is 3 μm and 15μm respectively. Therefore improvement of mechanical properties for such fine-grained steels is expected, it is important to understand the residual stress state of new fine-grained materials with processing. In this study, multi axial stresses of two kinds of specimens after polishing and grinding were measured by three kinds of analysis methods including cos-ψ method. As a result, as for σ33, the stress of NFG was compression, though that of SM490 was tension.

About Residual Stress State of Castings: The Case of HPDC Parts and Possible Advantages through Semi-Solid Processes

2022 ◽  
Vol 327 ◽  
pp. 272-278
Author(s):  
Elisa Fracchia ◽  
Federico Simone Gobber ◽  
Claudio Mus ◽  
Yuji Kobayashi ◽  
Mario Rosso
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Residual Stresses ◽  
Casting Process ◽  
Ray Method ◽  
Premature Failure ◽  
Thin Walls ◽  
Residual Stress State ◽  
Semi Solid ◽  
Pressure Die Casting

Nowadays, one of the most crucial focus in the aluminium-foundry sector is the production of high-quality castings. Mainly, High-Pressure Die Casting (HPDC) is broadly adopted, since by this process is possible to realize aluminium castings with thin walls and high specific mechanical properties. On the other hand, this casting process may cause tensile states into the castings, namely residual stresses. Residual stresses may strongly affect the life of the product causing premature failure of the casting. Various methods can assess these tensile states, but the non-destructive X-Ray method is the most commonly adopted. Namely, in this work, the residual stress analysis has been performed through Sinto-Pulstec μ-X360s. Detailed measurements have been done on powertrain components realized in aluminium alloy EN AC 46000 through HPDC processes to understand and prevent dangerous residual stress state into the aluminium castings. Furthermore, a comparison with stresses induced by Rheocasting processes is underway. In fact, it is well known that Semi-Solid metal forming combines the advantages of casting and forging, solving safety and environmental problems and possibly even the residual stress state can be positively affected.

Influence of Cup Wheel Grinding and Etching Pretreatment on Residual Stress and Surface Topography for Coated Cemented Carbide Tools

2012 ◽  
Vol 497 ◽  
pp. 10-14
Author(s):  
Tie Jun Song ◽  
Zhi Xiong Zhou ◽  
Wei Li ◽  
Ai Min Tang
Keyword(s):  
Residual Stress ◽  
Surface Topography ◽  
Cutting Tools ◽  
Wheel Speed ◽  
Cemented Carbide ◽  
Machining Process ◽  
Grinding Wheel ◽  
Near Surface ◽  
Cup Wheel ◽  
Coated Cemented Carbide

Cup wheel grinding and etching pretreatment are widely used in complex coated cemented carbide cutting tools machining process. The two processes determine different surface properties due to various mechanical and thermal loads in grinding and complex chemical reaction in etching pretreatment. In this paper, the effect of the grinding wheel speed, the grinding feed rate and the etching time with the Murakami and acid solution on the residual stress and surface topography of coated cemented carbide cutting tools are investigated. After each process, the samples are characterized by scanning electron microscopy and X-ray diffraction. It is found that the grinding wheel speed has a significant influence on residual stress measured in the WC phase. Etching by Murakami generated smooth surface, which partly removed the near-surface residual stress quickly but cannot eliminate.

scholarly journals Analysis of the Influence of Surface Modifications on the Fatigue Behavior of Hot Work Tool Steel Components

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7324
Author(s):  
Thomas Wild ◽  
Timo Platt ◽  
Dirk Biermann ◽  
Marion Merklein
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Surface Integrity ◽  
Fatigue Behavior ◽  
Hot Forging ◽  
Surface Modifications ◽  
Bending Test ◽  
Fatigue Properties ◽  
Machining Processes ◽  
Residual Stress State

Hot work tool steels (HWS) are widely used for high performance components as dies and molds in hot forging processes, where extreme process-related mechanical and thermal loads limit tool life. With the functionalizing and modification of tool surfaces with tailored surfaces, a promising approach is given to provide material flow control resulting in the efficient die filling of cavities while reducing the process forces. In terms of fatigue properties, the influence of surface modifications on surface integrity is insufficiently studied. Therefore, the potential of the machining processes of high-feed milling, micromilling and grinding with regard to the implications on the fatigue strength of components made of HWS (AISI H11) hardened to 50 ± 1 HRC was investigated. For this purpose, the machined surfaces were characterized in terms of surface topography and residual stress state to determine the surface integrity. In order to analyze the resulting fatigue behavior as a result of the machining processes, a rotating bending test was performed. The fracture surfaces were investigated using fractographic analysis to define the initiation area and to identify the source of failure. The investigations showed a significant influence of the machining-induced surface integrity and, in particular, the induced residual stress state on the fatigue properties of components made of HWS.

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