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.

Residual Stress Evaluation Induced by Fatigue Crack in Shot Peened, Notched Specimens

2017 ◽  
Vol 885 ◽  
pp. 280-285
Author(s):  
Dávid Cseh ◽  
Valéria Mertinger ◽  
János Lukács
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Stress Relaxation ◽  
Compressive Residual Stress ◽  
Diffraction Method ◽  
Fatigue Properties ◽  
Operational Parameters ◽  
Surface Residual Stress ◽  
Residual Stress State ◽  
Residual Stress Relaxation

The advantages of applied compressive residual stress on fatigue properties of materials is a well-described topic, but the residual stress state of machine elements can change during application, therefore it is necessary to describe how these changes are related to the operational parameters. So the monitoring of residual stress relaxation gives more details to improve the lifetime. The surface residual stress state evolution of hardened (quenched and tempered), shot peened, 2 side notched quadratic fatigue specimens made of 42CrMO4 steel was investigated nondestructively by X-ray diffraction method. Residual stress state was monitored on the surface with 1 mm spatial resolution in 5 mm environment of the notch. The compressive residual stress relaxation associated the notching and the fatigue test and the reversal of sign of the residual stress (from compression to tension) associated the crack propagation were experimentally showed.

Rolling Element Fatigue and Macroresidual Stress

1970 ◽  
Vol 92 (1) ◽  
pp. 76-81 ◽  
Author(s):  
R. K. Kepple ◽  
R. L. Mattson
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Biaxial Tension ◽  
Tangential Direction ◽  
Rolling Contact ◽  
Fatigue Properties ◽  
Biaxial Compression ◽  
Residual Stress State ◽  
Rolling Element ◽  
Better Than

An experimental investigation was made to determine the effect of the initial or residual stress state on rolling element fatigue life. This was done by simulating a residual stress by a mechanically applied static stress. Hoop-shaped specimens were statically stressed in both a tangential direction and a transverse direction to simulate either a biaxial tension or biaxial compression stress state and then subjected to repeated rolling contact until failure occurred. The results showed the rolling element fatigue properties for the compression state is not significantly better than the “zero” stress state, contrary to widely held opinion, and that the tensile state is detrimental to fatigue properties as expected.

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.

scholarly journals Effect of machine hammer peening on the surface integrity of a ZnAl-based corrosion protective coating

2020 ◽  
Vol 318 ◽  
pp. 01008
Author(s):  
Alina Timmermann ◽  
Mohamed Abdulgader ◽  
Leif Hagen ◽  
Alexander Koch ◽  
Philipp Wittke ◽  
...  
Keyword(s):  
Corrosion Fatigue ◽  
Surface Integrity ◽  
Protective Coatings ◽  
Fatigue Behavior ◽  
Turbine Blades ◽  
Fatigue Properties ◽  
Machine Hammer Peening ◽  
Coated Surfaces ◽  
Thermally Sprayed ◽  
Hammer Peening

Thermally sprayed protective coatings are applied onto many mechanically stressed components such as support structures, shafts, turbine blades or heat exchangers. In addition to the static or cyclic load, a superimposition with corrosion processes occurs in many cases. Thermal sprayed ZnAl coatings are known for their performant corrosion protection properties. Within this context, the potential of ZnAl-based layer systems was analyzed regarding corrosion fatigue behavior. Therefore, a timeand cost-efficient testing strategy based on a corrosion-superimposed load increase procedure was used to estimate the effects of a corrosive attack during cyclic loading. The investigated coating systems were thermally sprayed and partially post-processed with a Machine Hammer Peening (MHP) operation. This treatment was identified as an appropriate technique for compressing and smoothing coated surfaces. The inter-relationships between the parametrization of the MHP process, the resulting surface integrity, and the estimated corrosion fatigue properties were analyzed. The investigations indicate a positive effect of MHP post-processing operations on the surface properties of the ZnAl-based coating system.

Residual Stress State and Fatigue Behaviour of Laser Shock Peened Titanium Alloys

2006 ◽  
pp. 129-134
Author(s):  
I. Altenberger ◽  
Yuji Sano ◽  
M.A. Cherif ◽  
Ivan Nikitin ◽  
Berthold Scholtes
Keyword(s):  
Residual Stress ◽  
Stress State ◽  
Titanium Alloys ◽  
Fatigue Behaviour ◽  
Laser Shock ◽  
Residual Stress State

scholarly journals The Effect of Milling Cooling Conditions on the Surface Integrity and Fatigue Behavior of the GH4169 Superalloy

Metals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1179 ◽  
Author(s):  
Rufeng Xu ◽  
Yongxin Zhou ◽  
Xun Li ◽  
Shenliang Yang ◽  
Kangning Han ◽  
...  
Keyword(s):  
Surface Integrity ◽  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Fatigue Properties ◽  
Dry Milling ◽  
Wet Milling ◽  
Machined Surface ◽  
Side Milling ◽  
Cooling Conditions ◽  
Gh4169 Superalloy

The GH4169 superalloy has high strength at high temperatures. Cooling conditions have a major impact on the machined surface integrity, which further affects the fatigue properties of specimens of the GH4169 superalloy. The influence of cooling conditions on the surface integrity of the GH4169 superalloy is first studied during the side milling. Then, the effect of surface integrity under different cooling conditions on the fatigue behavior of specimens of the GH4169 superalloy is investigated by a standard tensile and tensile–mode fatigue testing. The results obtained show that surface roughness and the depth of the plastic deformation layer in wet milling and dry milling makes little difference, the surface microhardness rate in dry milling is slightly lower than that in wet milling, the surface tensile residual stress in dry milling is significantly higher than that in wet milling, and the fatigue behavior in dry milling is only about 50% of that in wet milling. In addition, the crack initiation of specimens of the GH4169 superalloy utilizing wet milling is on the subsurface, while that from dry milling is on the surface. Thus, cooling conditions have an important impact on the fatigue behavior of specimens of the GH4169 superalloy, and micro defects in dry milling are the main factors of decreasing of fatigue behavior of specimens of the GH4169 superalloy.

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