Improvement in the fatigue strength of chromium electroplated AISI 4340 steel by shot peening (original) (raw)
Related papers
Materials Research, 2002
Multiple layer systems of coatings are considered to have larger resistance to crack propagation in comparison to coatings with simple layer. With regard to fatigue, it is possible to improve the resistance of a component with the application of shot peening treatment, whose compressive residual stresses delay or eliminate the initiation and propagation of fatigue cracks. The aim of this study is to analyse the effects on rotating bending fatigue behaviour of hard chromiumelectroless nickel multilayer system coated AISI 4340 high strength steel submitted to shot peening pre treatment. Results indicated that the interaction between the shot peening process with the multilayer system was not satisfactory, resulting in intense delamination. Fracture surface analysis by SEM was performed toward to identify the fatigue crack origin, as well as the coatingsubstrate delamination process.
Effects of surface treatments on the fatigue strength of AISI 4340 aeronautical steel
… journal of fatigue, 2001
Internal residual stresses significantly influence the fatigue strength of coated materials. It is well known that chromium plating is the most used electrodeposited coating for important industrial applications. However, pressure to identify alternatives or to improve the chromium electroplating process have increased in recent years, related to the reduction in fatigue strength of the base material and to environmental requirements. The high efficiency and fluoride free hard chromium electroplating (here called "accelerated") is an improvement to the conventional process. One environmentally safer and cleaner alternative to hard chromium plating is tungsten carbide thermal spray coating applied by the High Velocity Oxy-Fuel (HVOF) process. To increase the fatigue strength of chromium plated materials, coating thickness and microcracks density are important parameters to be controlled. Techniques as compressive residual stresses induced by shot peening and multilayers, are also used. The aim of this study was to analyse the effects on AISI 4340 steel, in the rotating bending fatigue behaviour, of the: tungsten carbide thermal spray coating applied by HP/HVOF process; chemical nickel underplate, and shot peening process applied before coating deposition, in comparison to hard chromium electroplatings. Rotating bending fatigue test results indicate better performance for the conventional hard chromium plating in relation to the accelerated hard chromium electroplating. Tungsten carbide thermal spray coating and accelerated hard chromium plate over nickel resulted in higher fatigue strength when compared to samples conventional or accelerated hard chromium plated. Shot peening showed to be an excellent alternative to increase fatigue strength of AISI 4340 steel hard chromium electroplated.
Comparison of Fatigue Characteristic for AISI 1039 Steel with Surface Treatment
Wear and fatigue resistance in steel components used in various industries can be improved by surface treatments. Coatings systems which are used for improving the mechanical properties, generally, decreased the components fatigue life due to micro cracks, that propagate through the substrate , it is possible to improve the fatigue resistance of a component by the application of shot peening treatment, whose compressive residual stresses delay or eliminate the initiation and propagation of fatigue cracks. The aim of this study is to obtain the fatigue limit of untreated, shot peened, and hard chromium coating of medium carbon steel AISI 1039 and comparison between them. Fatigue tests were carried out using small samples with 4 mm diameter, with hard chromium layer of (47.1) µm thick. Rotating-bending fatigue test was carried out on samples after shot peening with steel balls of about 20 minutes peening time. Experimental results showed that hard chromium electroplating decreased the fatigue life and fatigue limit in comparison with the uncoated steel. As the highest thickness for coating was 23µm. On the other hand, Shot peening Results indicated that the fatigue strengths of samples are increased and the highest fatigue limit was (298.566Mpa) after treated the samples by shot peening for 20 minutes.
2005
300M steel is widely used in aircraft landing gear because of its unique com strength and fracture toughness, but is vulnerable to foreign object damage (FOE), corrosion fatigue, and stress corrosion cracking (SCC) failures with potentially catastrophic consequences. The fatigue, corrosion fatigue in salt water, and SCC performance of LPB processed 300M steel was compared with shot peened (SP) and low stress ground (LSG) conditions. LPB, with and without simulated FOD, produced deep residual compression that dramatically improved both the HCF and corrosion fatigue strength. The fatigue strength of LSG and SF9 treated surfaces was drastically reduced by salt and FOD exposure with no discernible endurance limit for corrosion fatigue conditions. SCC testing of LPB treated landing gear sections at 1030 to 2270 MPa (150 to 180 ksi) static loads was terminated after 1500 hrs without failure, compared to failure in as little as 13 hours without treatment. Mechanistically, the deep compressive surface residual stresses from LPB treatment mitigated both the individual and synergistic effects of corrosion fatigue and FOD. LPB also reduced the surface stress well below the SCC threshold for 300M, even under high tensile applied stresses, effectively suppressing the SCC failure mechanism.
Procedia Engineering, 2010
Fatigue failure is a result of a crack initiation and propagation, in consequence of a cyclical load. In aeronautical components as landing gear the fatigue strength is an important parameter to be considered in project, as well as the corrosion and wear resistance. The thermal sprayed HVOF technology it's normally used to protect components against wear and corrosion, and are being considerate an alternative to replace chromium by the aeronautical industry. With respect to fatigue life, the HVOF technique induces residual stress on the interface. In the case of tensile residual stresses, the initiation and propagation phases of fatigue process are accelerated; on the other hand, compressive residual stresses close to the surface may increase fatigue life. The technique to improve the coated materials fatigue strength is the shot peening process, which induces residual stress in the surface in order to delay the nucleation and propagation process. The aim of present study is to compare the influence of WC-10 Ni coating applied by HVOF on the fatigue strength of AISI 4340 steel, with and without shot peening. S-N curves were obtained in axial fatigue tests for material base, and tungsten carbide coated specimens.
shotpeener.com
300M steel is widely used in aircraft landing gear because of its unique com strength and fracture toughness, but is vulnerable to foreign object damage (FOE), corrosion fatigue, and stress corrosion cracking (SCC) failures with potentially catastrophic consequences. The fatigue, corrosion fatigue in salt water, and SCC performance of LPB processed 300M steel was compared with shot peened (SP) and low stress ground (LSG) conditions. LPB, with and without simulated FOD, produced deep residual compression that dramatically improved both the HCF and corrosion fatigue strength. The fatigue strength of LSG and SF9 treated surfaces was drastically reduced by salt and FOD exposure with no discernible endurance limit for corrosion fatigue conditions. SCC testing of LPB treated landing gear sections at 1030 to 2270 MPa (150 to 180 ksi) static loads was terminated after 1500 hrs without failure, compared to failure in as little as 13 hours without treatment. Mechanistically, the deep compressive surface residual stresses from LPB treatment mitigated both the individual and synergistic effects of corrosion fatigue and FOD. LPB also reduced the surface stress well below the SCC threshold for 300M, even under high tensile applied stresses, effectively suppressing the SCC failure mechanism.
Effects of shot peening and artificial surface defects on fatigue properties of 50CrV4 steel
The International Journal of Advanced Manufacturing Technology, 2021
Shot peening processes are commonly used for improving the fatigue properties of steels. Shot peening introduces a compressive residual stress field in the near surface of steel, which can reduce or stop the growth of fatigue cracks and improve fatigue properties. This study experimentally investigated the effect of shot peening on the fatigue properties of 50CrV4 steel alloys with different artificial surface defects. Drilling tools were used to introduce different artificial defects with root radii of 0.585 mm and 0.895 mm on the surface of unpeened samples. The shot peening was applied to the drilled and undrilled samples. Scanning electron microscopy (SEM) observations, micro-hardness and X-ray diffraction residual stress measurements were conducted to analyse the characteristics of the shot-peened and unpeened samples. The results show that the shot peening leads to the transformation of the retained austenite to martensite in the near-surface microstructure. The hardness rates...
Fatigue behavior of X70 microalloyed steel after severe shot peening
International Journal of Fatigue, 2013
The so called ''severe plastic deformation'' (SPD) processes are object of increasing interest due to their ability to obtain a nanostructured surface layer of material with supposed superior properties. Among these processes, severe shot peening (SSP) is very attractive from an industrial point of view, due to its versatility and wide applicability.
Fatigue in AISI 4340 steel thermal spray coating by HVOF for aeronautic application
Procedia Engineering, 2010
Currently, high-strength materials, particularly AISI 4340 steel, are used in several landing gear components. Due to the high resistance to wear and corrosion required, the components are usually coating by hard chromium. This treatment produces waste, such as Cr+6 (hexavalent chromium), generally after applying the coating of hard chromium which is harmful to health and the environment. The process HVOF (High-velocity-oxygen-fuel) is considered a promising technique for deposition of hard chromium alternative coatings, for example, coatings based on tungsten carbide. This technique provides high hardness and good wear strength and more resistance to fatigue when compared to AISI 4340 hard chromium coated. To minimize loss fatigue due to the process of deposition, shot peening is used to obtain a compressive residual stress. The aim of this study was to analyze the effects of the tungsten carbide thermal spray coating applied by the HVOF, in comparison to the conventional hard chromium electroplating on the AISI 4340 high strength steel behavior in fatigue. Optical microscopy and scanning electron microscopy were used to observe crack origin sites, thickness and adhesion of the coating.
Metals and Materials International
This study investigates and compares the effects of different shot peening treatments including conventional and severe shot peening on microstructure, mechanical properties, fatigue behavior, and residual stress relaxation of AISI 1060 steel. Shot peening treatments were applied with two Almen intensities of 17 and 21 A and a wide ranges of coverage (100%–1500%). Various microstructural observations were carried out to analyze the evolution of microstructure. Microhardness, residual stress and surface roughness measurements and also axial fatigue test were performed. Moreover, the extent of the residual stress relaxation during cyclic loading was investigated by means of XRD measurements. Furthermore, numerical simulation of residual stress relaxation due to fatigue loading was carried out and validated against experimental investigations. The comparison indicated a good agreement for the surface residual stress relaxation up to 100 cycles. The experimental results indicated the ef...