Comparison of Fatigue Characteristic for AISI 1039 Steel with Surface Treatment (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.
Improvement in the fatigue strength of chromium electroplated AISI 4340 steel by shot peening
Fatigue & Fracture of Engineering Materials & Structures, 2009
In landing gear, an important mechanical component for high responsible applications, wear and corrosion control is currently accomplished by chrome plating or hard anodising. However, some problems are associated with these operations. Experimental results have also shown that chrome-plated specimens have fatigue strength lower than those of uncoated parts, attributed to high residual tensile stress and microcracks density contained into the coating. Under fatigue conditions these microcracks propagate and will cross the interface coating-substrate and penetrate base metal without impediment. Shot peening is a surface process used to improve fatigue strength of metal components due to compressive residual stresses induced in the surface layers of the material, making the nucleation and propagation of fatigue cracks difficult. This investigation is concerned with analysis of the shot peening influence on the rotating bending fatigue strength of hard chromium electroplated AISI 4340 steel. Specimens were submitted to shot peening treatment with steel and ceramic shots and, in both cases, experimental results show increase in the fatigue life of AISI 4340 steel hard chromium electroplated, up to level of base metal without chromium. Peening using ceramic shot resulted in lower scatter in rotating bending fatigue data than steel shots.
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.
Investigating Effect of Industrial Coatings on Fatigue Damage
2011
Investigating Fatigue is one the most important factors in designing most mechanical structure. The reason is that, in many cases, the specimens of the structure break down without any warning or signal. Nano and micron's Coatings are finding more and more applications in industry such as aerospace, automotive, and naval industries. The present article has a purpose. Firstly, it intends to explore the influence of four industrial coatings, namely, hardened chromium, embellished chromium, hardened nickel, and warm galvanizing, all of which have the thickness value at micron levels on fatigue specimens. Moreover, it aims to find the most convenient coating. To achieve these purposes, the abovementioned coatings with the thickness of 13 & 19 were coated on standard specimens who were made of CK45 steel under the same conditions. Then, the S-N curve of each sample was attained empirically according to the standard fatigue testing. Specimens are simulated in the finite element analysis according to experimental conditions and then S-N curve of each sample was attained. Finally, comparing the S-N curves, the most appropriate coating is introduced for the delineated conditions and based fatigue results may be predicted damage of coating.
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.
Journal of Materials Engineering and Performance, 2005
It is well known that fatigue behaviour is an important parameter to be considered in mechanical components subjected to constant and variable amplitude loadings. In combination with corrosion phenomenon, fatigue effects were responsible for proximally 64% of fails that occur in metallic parts of aeronautical accidents in the last 30 years. Recovered substrates have been extensively used in the aerospace field. Cadmium electroplating has been widely applied to promote protective coatings in aeronautical components, resulting in excellent corrosion protection combined with a good performance in cyclic loading. Ecological considerations allied to the increasing demands for corrosion resistance, resulted in the search for possible alternatives. Zinc-nickel alloys received considerable interest recently, since these coatings showed some advantages such as a good resistance to white and red rust, high plating rates and acceptation in the market. In this study the effects of zinc-nickel coatings electroplated on AISI 4340 high strength steel were analysed on rotating bending and axial fatigue strength, corrosion and adhesion resistance. Compressive residual stress field was measured by a X-ray tensometry prior to fatigue tests. Optical microscopy images showed coating thicknesses, adhesion and the existence of an uniform coverage of nearly all substrates. The fractured fatigue specimens were investigated using a scanning electron microscope. Three different zinc-nickel coating thicknesses were tested and comparison with rotating bending fatigue data from specimens cadmium electroplated and heat treated at 190°C for 3, 8 and 24 hours to avoid the diffusion of hydrogen in the substrate, was performed. Experimental results showed effect of coatings on the AISI 4340 steel behaviour when submitted to fatigue testing and the existence of coating thickness influence on the fatigue strength.
An investigation into the effect of various surface treatments on fatigue life of a tool steel
Journal of Materials Processing Technology, 2006
The effects of nitriding, nitrocarburizing and shot peening on fatigue behavior of AISI D3 cold work tool steel were investigated. Five batches of fatigue specimens were manufactured according to the ASTM E466-96 standard. All specimens were quenched and tempered to a hardness of 50 HRC. One group of specimens was shot peened with an Almen intensity of 16 A, one group was nitrocarburized, one group was gas nitrided by single stage and another group was also nitrided by double stages. Rotating-bending fatigue tests were carried out. Our results showed that nitriding and nitrocarburizing treatments did not have a beneficial effect on the fatigue resistance of D3 tool steel. Fatigue test results revealed that shot peening increased the fatigue life of specimens by about 14%, while double stage nitriding decreased it by about 8%. Nitrocarburizing and single stage nitriding decreased the fatigue life of specimens by about 29% and 50%, respectively. Nitriding and nitrocarburizing treatments may improve abrasive-wear resistance of this material by increasing surface hardness but may promote the easy nucleation of a fatigue crack in the brittle surface layer and its unimpeded growth into the weaker substrate material. However, double stage nitriding is less damaging to the fatigue behavior of this steel. SEM and metallographic investigations indicated that a compound layer with porous structure was formed during nitriding and nitrocarburizing. So shot peening is the best treatment to improve the fatigue life of AISI D3 tool steel.
Fatigue strength of HVOF sprayed Cr3C2–25NiCr and WC-10Ni on AISI 4340 steel
Surface and Coatings Technology, 2008
The fatigue strength of coated material is significantly influenced by internal residual stresses. Chromium coatings are used in applications to guarantee protection against wear and corrosion, combined with chemical resistance and good lubricity. The reduction in the fatigue strength of base material and since this technology presents detrimental environmental and health effects, resulted in the search on coatings viewed as being capable of replacing hard chrome plating. Thermally sprayed HVOF coatings are being considered to replace galvanic chromium deposits in industrial applications with, at least, comparable performance with respect to wear and corrosion resistance. The aim of the present study is to compare the influence of Cr 3 C 2-25NiCr and WC-10Ni coatings applied by HVOF process and hard chromium electroplating on the fatigue strength, abrasive wear and corrosion resistance of AISI 4340 steel. S-N curves were obtained in axial fatigue tests for base material, chromium plated and HVOF coated specimens. Experimental data showed higher axial fatigue resistance for HVOF coated specimens in comparison to electroplated chromium. The wear weight loss tests indicated better results for the HVOF thermal spray processing in comparison to the chromium electroplating. An increase in the corrosion resistance of steel protected with WC-10Ni HVOF coatings occurred with increased coating thickness. For Cr 3 C 2-25NiCr HVOF coating, results indicate clearly the higher salt spray resistance.
Residual stress influence on fatigue lifetimes of electroplated AISI 4340 high strength steel
Fatigue & Fracture of Engineering Materials and Structures, 2007
In the case of near surface 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. In both decorative and functional applications, chromium electroplating results in excellent wear and corrosion resistance. However, it is well known that it reduces the fatigue strength of a component. This is due to high tensile internal stresses and microcrack density. Efforts to improve hard chromium properties have increased in recent years. In this study, the effect of a nickel layer sulphamate process, as simple layer and interlayer, on fatigue strength of hard chromium electroplated AISI 4340 steel hardness-HRc 53, was analysed. The analysis was performed by rotating bending fatigue tests on AISI 4340 steel specimens with the following experimental groups: base material, hard chromium electroplated, sulphamate nickel electroplated, sulphamate nickel interlayer on hard chromium electroplated and electroless nickel interlayer on hard chromium electroplated. Results showed a decrease in fatigue strength in coated specimens and that both nickel plating interlayers were responsible for the increase in fatigue life of AISI 4340 chromium electroplated steel. The shot peening pre-treatment was efficient in reducing fatigue loss in the alternatives studied.
Fatigue <html_ent glyph="@amp;" ascii="&"/> Fracture of Engineering Materials and Structures, 2006
The effect of a plasma nitriding (PN) pre-treatment on the fatigue performance of hard chromium (HC) plated AISI 4140 steel has been investigated by conducting a series of rotary bending fatigue tests at a frequency of 95 Hz. hourglass shaped test specimens of 4-mm diameter had been plasma nitrided at 510 • C for 4, 8 and 12 h. It was found that HC-plated specimens with a coating layer of 23 ± 2 µm thickness showed approximately 33% reduction in fatigue strength when compared to quenched and tempered (Q&T) specimens. An application of the PN pre-treatment before the plating process was effective in improving the fatigue performance of HC-coated steel. An improvement of 71% in the fatigue strength of pre-treated specimens was recorded as compared with the specimens, which were HC plated only. The results also indicated that prolonged nitriding time did not cause better improvement in the fatigue performance. Keywords fatigue; hard chromium plating; hardness; plasma nitriding.