Restoring Fatigue Performance of Corrosion Damaged Aa7075-T6 and Fretting in 4340 Steel with Low Plasticity Burnishing

2002 ◽  
Author(s):  
Paul S. Prevey ◽  
John T. Cammett
Keyword(s):  
Fatigue Performance ◽  
4340 Steel ◽  
Low Plasticity Burnishing

scholarly journals Case Studies of Fatigue Life Improvement Using Low Plasticity Burnishing in Gas Turbine Engine Applications

2003 ◽  
Author(s):  
Paul S. Preve´y ◽  
Ravi A. Ravindranath ◽  
Michael Shepard ◽  
Timothy Gabb
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Case Studies ◽  
Shot Peening ◽  
Damage Tolerance ◽  
Cold Work ◽  
Fatigue Performance ◽  
Surface Enhancement ◽  
Low Plasticity Burnishing ◽  
Life Improvement

Surface enhancement technologies such as shot peening, laser shock peening (LSP), and low plasticity burnishing (LPB) can provide substantial fatigue life improvement. However, to be effective, the compressive residual stresses that increase fatigue strength must be retained in service. For successful integration into turbine design, the process must be affordable and compatible with the manufacturing environment. LPB provides thermally stable compression of comparable magnitude and even greater depth than other methods, and can be performed in conventional machine shop environments on CNC machine tools. LPB provides a means to extend the fatigue lives of both new and legacy aircraft engines and ground-based turbines. Improving fatigue performance by introducing deep stable layers of compressive residual stress avoids the generally cost prohibitive alternative of modifying either material or design. The x-ray diffraction based background studies of thermal and mechanical stability of surface enhancement techniques are briefly reviewed, demonstrating the importance of minimizing cold work. The LPB process, tooling, and control systems are described. An overview of current research programs conducted for engine OEMs and the military to apply LPB to a variety of engine and aging aircraft components are presented. Fatigue performance and residual stress data developed to date for several case studies are presented including: • The effect of LPB on the fatigue performance of the nickel based super alloy IN718, showing the fatigue benefit of thermal stability at engine temperatures. • An order of magnitude improvement in damage tolerance of LPB processed Ti-6-4 fan blade leading edges. • Elimination of the fretting fatigue debit for Ti-6-4 with prior LPB. • Corrosion fatigue mitigation with LPB in Carpenter 450 steel. • Damage tolerance improvement in 17-4PH steel. Where appropriate, the performance of LPB is compared to conventional shot peening after exposure to engine operating temperatures.

scholarly journals Case Studies of Fatigue Life Improvement Using Low Plasticity Burnishing in Gas Turbine Engine Applications

2006 ◽  
Vol 128 (4) ◽  
pp. 865-872 ◽  
Author(s):  
Paul S. Preve´y ◽  
Ravi A. Ravindranath ◽  
Michael Shepard ◽  
Timothy Gabb
Keyword(s):  
Residual Stress ◽  
Fatigue Life ◽  
Case Studies ◽  
Shot Peening ◽  
Damage Tolerance ◽  
Cold Work ◽  
Fatigue Performance ◽  
Surface Enhancement ◽  
Low Plasticity Burnishing ◽  
Life Improvement

Surface enhancement technologies such as shot peening, laser shock peening, and low plasticity burnishing (LPB) can provide substantial fatigue life improvement. However, to be effective, the compressive residual stresses that increase fatigue strength must be retained in service. For successful integration into turbine design, the process must be affordable and compatible with the manufacturing environment. LPB provides thermally stable compression of comparable magnitude and even greater depth than other methods, and can be performed in conventional machine shop environments on CNC machine tools. LPB provides a means to extend the fatigue lives of both new and legacy aircraft engines and ground-based turbines. Improving fatigue performance by introducing deep stable layers of compressive residual stress avoids the generally cost prohibitive alternative of modifying either material or design. The x-ray diffraction based background studies of thermal and mechanical stability of surface enhancement techniques are briefly reviewed, demonstrating the importance of minimizing cold work. The LPB process, tooling, and control systems are described. An overview of current research programs conducted for engine OEMs and the military to apply LPB to a variety of engine and aging aircraft components are presented. Fatigue performance and residual stress data developed to date for several case studies are presented including the following. (1) The effect of LPB on the fatigue performance of the nickel based super alloy IN718, showing the fatigue benefit of thermal stability at engine temperatures. (2) An order of magnitude improvement in damage tolerance of LPB processed Ti-6-4 fan blade leading edges. (3) Elimination of the fretting fatigue debit for Ti-6-4 with prior LPB. (4) Corrosion fatigue mitigation with LPB in Carpenter 450 steel. (5) Damage tolerance improvement in 17-4 PH steel. Where appropriate, the performance of LPB is compared to conventional shot peening after exposure to engine operating temperatures.

scholarly journals Study of the Surface Integrity and High Cycle Fatigue Performance of AISI 4340 Steel after Composite Surface Modification

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 856 ◽  
Author(s):  
Hai Fu ◽  
Yilong Liang
Keyword(s):  
Plastic Deformation ◽  
Surface Modification ◽  
Fatigue Performance ◽  
Cycle Fatigue ◽  
Composite Surface ◽  
Aisi 4340 Steel ◽  
Good Surface ◽  
4340 Steel ◽  
Deformation Layer ◽  
Aisi 4340

In the field of materials science, the fabrication of a material with severe surface plastic deformation and a good surface state is an issue encountered in the development of counterbalanced gradient materials. For this paper, AISI 4340 steel was first processed with abrasive water jet peening (AWJP) and then with ultrasonic surface rolling (USRE) to obtain a good surface state while maintaining large plastic deformation. The AISI 4340 steel composite surface was therefore modified, and the surface integrity and cycle fatigue performance were analyzed. The results show that the plastic deformation layer of the modified composite surface of the 4340 steel was 310 µm from the surface of the sample, the grain size 40 µm from the surface layer was refined to 70 nm, and the maximum surface roughness Ra is 0.06. The fatigue limit of the modified composite surfaces obtained by the tensile fatigue test was 595.7 MPa, which was 85.7 MPa higher than the 510 MPa fatigue limit of the unmodified matrix, indicating that the method of composite surface modification can produce a deep deformation layer while maintaining good surface conditions. The results show that work hardening caused by a composite surface treatment is the most important factor for improving the fatigue performance of materials.

scholarly journals Fatigue Performance of AISI 4340 Steel Ni-Cr-B-Si-Fe HVOF Thermal Spray Coated

2015 ◽  
Vol 114 ◽  
pp. 606-612 ◽  
Author(s):  
L.F.S. Vieira ◽  
H.J.C. Voorwald ◽  
M.O.H. Cioffi
Keyword(s):  
Thermal Spray ◽  
Fatigue Performance ◽  
Aisi 4340 Steel ◽  
4340 Steel ◽  
Hvof Thermal Spray ◽  
Aisi 4340
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