Effects of residual stresses on high-cycle fatigue

1993 ◽  
Vol 15 (6) ◽  
pp. 536
Keyword(s):  
Residual Stresses ◽  
High Cycle Fatigue ◽  
Cycle Fatigue

Crystal Plasticity Modeling of Laser Peening Effects on Tensile and High Cycle Fatigue Properties of 2024-T351 Aluminum Alloy

2021 ◽  
Vol 143 (7) ◽  
Author(s):  
Maziar Toursangsaraki ◽  
Huamiao Wang ◽  
Yongxiang Hu ◽  
Dhandapanik Karthik
Keyword(s):  
Residual Stresses ◽  
Crystal Plasticity ◽  
High Cycle Fatigue ◽  
Driving Forces ◽  
Crack Nucleation ◽  
Fatigue Properties ◽  
Laser Peening ◽  
Cycle Fatigue ◽  
Fatigue Crack Nucleation ◽  
Near Surface

Abstract This study aims to model the effects of multiple laser peening (LP) on the mechanical properties of AA2024-T351 by including the material microstructure and residual stresses using the crystal plasticity finite element method (CPFEM). In this approach, the LP-induced compressive residual stress distribution is modeled through the insertion of the Eigenstrains as a function of depth, which is calibrated by the X-ray measured residual stresses. The simulated enhancement in the tensile properties after LP, caused by the formation of a near-surface work-hardened layer, fits the experimentally obtained tensile curves. The model calculated fatigue indicator parameters (FIPs) under the following cyclic loading application show a decrease in the near-surface driving forces for the crystal slip deformation after the insertion of the Eigenstrains. This leads to a higher high cycle fatigue (HCF) resistance and the possible transformation of sensitive locations for fatigue failure further to the depth after LP. Experimental observations on the enhancement in the HCF life, along with the relocation of fatigue crack nucleation sites further to the depth, reveal the improvement in the HCF properties due to the LP process and validate the numerical approach.

Effect of Preheat on Improving Beneficial Surface Residual Stresses During Induction Hardening Process

2016 ◽  
Author(s):  
Zhichao (Charlie) Li ◽  
Andrew Freborg ◽  
Lynn Ferguson
Keyword(s):  
Residual Stresses ◽  
High Cycle Fatigue ◽  
Induction Hardening ◽  
Heating Time ◽  
Single Shot ◽  
Cycle Fatigue ◽  
Steel Component ◽  
Hardening Process ◽  
Surface Residual Stresses ◽  
Residual Compression

Applications of the induction hardening process have been gradually increasing in the heat treatment industry due to its energy efficiency, process consistency, and clean environment. Compared to traditional furnace heating and liquid quenching processes, induction hardening is more flexible in terms of process control, and it can offer improved part quality. The commonly modified parameters for the process include the inductor power and frequency, heating time, spray quench delay and quench severity, etc. In this study, a single shot induction hardening process of a cylindrical component made of AISI 4340 is modeled using DANTE®. It is known that the residual stresses in a hardened steel component have a significant effect on high cycle fatigue performance, with higher magnitudes of surface residual compression leading to improved high cycle fatigue life. Induction hardening of steel components produces surface residual compression due to the martensitic transformation of the hardened surface layer, with a high magnitude of compression preferred for improved performance in general. In this paper, a preheat concept is proposed with the induction hardening process for enhanced surface residual compression in the hardened case. Preheating can be implemented using either furnace or low power induction heating, and both processes are modeled using DANTE to demonstrate its effectiveness. With the help of computer modeling, the reasons for the development of residual stresses in an induction hardened part are described, and how the preheat can be used to improve the magnitude of surface residual compression is explained.

Improving Corrosion Fatigue and Damage Performance of 410 Stainless Steel via LPB

2012 ◽  
Author(s):  
Douglas J. Hornbach ◽  
Jeremy E. Scheel
Keyword(s):  
Stainless Steel ◽  
Residual Stresses ◽  
Corrosion Fatigue ◽  
Shot Peening ◽  
High Cycle Fatigue ◽  
Damage Tolerance ◽  
Foreign Object ◽  
Cycle Fatigue ◽  
Foreign Object Damage ◽  
Compressive Residual Stresses

Stress corrosion cracking (SCC) and corrosion fatigue (CF) of 12% Cr stainless steel components can lead to reduced availability of steam turbines (ST). Significant operation and maintenance (O&M) costs are required to protect against CF and SCC in both aging and new higher efficiency ST systems. Shot peening has been used to reduce the overall operating tensile stresses, however corrosion pits, foreign object damage (FOD), and erosion can penetrate below the relatively shallow residual compression providing initiation sites for SCC and CF. A means of reliably introducing a deep layer of compressive residual stresses in critical ST components will greatly reduce O&M costs by improving CF life, increasing damage tolerance, reducing SCC susceptibility, and extending the service life of components. Low plasticity burnishing (LPB) is an advanced surface enhancement process providing a means of introducing compressive residual stresses into metallic components for enhanced fatigue, damage tolerance, and SCC performance. LPB processing can be applied as a repair process during scheduled overhauls or on new production components. High cycle fatigue tests were conducted on Type 410 stainless steel, a common alloy used in critical ST components, to compare the corrosion fatigue benefits of LPB to shot peening. Samples were tested in an active corrosion medium of 3.5% NaCl solution. Mechanical or accelerated corrosion damage was placed in test samples to simulate foreign object damage, pitting damage and water droplet erosion prior to testing. High cycle fatigue and residual stress results are shown. Compression from LPB was much deeper than the damage providing a nominal 100X improvement in fatigue life compared to the shallow compression from SP. Life extension from LPB offers significant O&M cost savings, improved reliability, and reduced outages for ST power generators.

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