scholarly journals Fractographic investigation of Low Cycle Fatigue behaviour of IN718 coated with NaCl at 550°C

2021 ◽  
Vol 2007 (1) ◽  
pp. 012070
Author(s):  
Mukesh Kumar
Keyword(s):  
Low Cycle Fatigue ◽  
Fatigue Behaviour ◽  
Cycle Fatigue ◽  
Fractographic Investigation

Low-Cycle Fatigue Behaviour of Gas Turbine Alloys

1974 ◽  
Vol 188 (1) ◽  
pp. 321-328 ◽  
Author(s):  
W. J. Evans ◽  
G. P. Tilly
Keyword(s):  
Low Cycle Fatigue ◽  
Fatigue Cracks ◽  
High Stress ◽  
Cyclic Creep ◽  
Fatigue Curve ◽  
Fatigue Behaviour ◽  
Material Surface ◽  
Tension Stress ◽  
Cycle Fatigue ◽  
Stress Tests

The low-cycle fatigue characteristics of an 11 per cent chromium steel, two nickel alloys and two titanium alloys have been studied in the range 20° to 500°C. For repeated-tension stress tests on all the materials, there was a sharp break in the stress-endurance curve between 103 and 104 cycles. The high stress failures were attributed to cyclic creep contributing to the development of internal cavities. At lower stresses, failures occurred through the growth of fatigue cracks initiated at the material surface. The whole fatigue curve could be represented by an expression developed from linear damage assumptions. Data for different temperatures and types of stress concentration were correlated by expressing stress as a fraction of the static strength. Repeated-tensile strain cycling data were represented on a stress-endurance diagram and it was shown that they correlated with push-pull stress cycles at high stresses and repeated-tension at low stresses. In general, the compressive phase tended to accentuate cyclic creep so that ductile failures occurred at proportionally lower stresses. Changes in frequency from 1 to 100 cycle/min were shown to have no significant effect on low-cycle fatigue behaviour.

scholarly journals Low Cycle Fatigue Behaviour of Austenitic Stainless Steel at Cyrogenic Temperature

1982 ◽  
Vol 68 (3) ◽  
pp. 471-476 ◽  
Author(s):  
Toshinori NAKAMURA ◽  
Masatake TOMINAGA ◽  
Hirokazu MURASE ◽  
Yukio NISHIYAMA
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Low Cycle Fatigue ◽  
Fatigue Behaviour ◽  
Cycle Fatigue

scholarly journals Low-cycle fatigue behaviour of laser welded high-strength steel DOMEX 700 MC

2018 ◽  
Vol 157 ◽  
pp. 05013 ◽  
Author(s):  
Peter Kopas ◽  
Milan Sága ◽  
František Nový ◽  
Bohuš Leitner
Keyword(s):  
Fatigue Life ◽  
Welded Joints ◽  
High Strength Steel ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
High Strength ◽  
Fatigue Behaviour ◽  
Total Strain Amplitude ◽  
Cycle Fatigue ◽  
Fatigue Life Analysis

The article presents the results of research on low cycle fatigue strength of laser welded joints vs. non-welded material of high-strength steel DOMEX 700 MC. The tests were performed under load controlled using the total strain amplitude ɛac. The operating principle of the special electro-mechanic fatigue testing equipment with a suitable clamping system was working on 35 Hz frequency. Fatigue life analysis was conducted based on the Manson-Coffin-Basquin equation, which made it possible to determine fatigue parameters. Studies have shown differences in the fatigue life of original specimens and laser welded joints analysed, where laser welded joints showed lower fatigue resistance. In this article a numerical analysis of stresses generated in bending fatigue specimens has been performed employing the commercially available FEM-program ADINA.

Fatigue Behaviour of the Novel Titanium Alloys TIMETAL® 407 and TIMETAL® 412

2021 ◽  
Author(s):  
◽  
William Davey
Keyword(s):  
Crack Initiation ◽  
Titanium Alloys ◽  
Low Cycle Fatigue ◽  
Fatigue Crack Initiation ◽  
Charpy Impact ◽  
Fatigue Behaviour ◽  
High Energy ◽  
Process Window ◽  
Cycle Fatigue ◽  
The Impact

TIMETAL®407 (Ti-407) is a medium strength (~650MPa 0.2%YS) titanium alloy, recently developed by TIMET, in conjunction with Rolls-Royce plc for use in applications requiring high energy absorption at impact. Preliminary Charpy Impact (V notch) testing showed Ti-407 to absorb nearly twice the impact energy of Ti-6-4 and exhibit more than 2.5 times the lateral expansion. Further initial testing suggested the high cycle fatigue (HCF) run out stress of Ti-407 matches that of Ti-6-4 and other high strength alpha-beta titanium alloys. Ti-407 displayed more than double the tool life than that of Ti-6-4. The reduction in tool wear supports lower forces required for faster, more efficient machining. Compared to Ti-6-4, the relatively low elevated temperature flow stress, greater malleability and wide process window should allow Ti-407 to be processed with fewer reheats, while exhibiting reduced surface cracking and giving a consistently good surface finish. Optimised Ti-407 manufacturing processes should allow parts to be formed closer to net shape giving higher yields and requiring less machining to the components finished size. This project has evaluated HCF, as well as low cycle fatigue (LCF) and dwell fatigue crack initiation mechanisms in Ti-407, to clarify the effects of alloy chemistry, microstructural morphology and scale, and crystallographic texture. A derivative of Ti-407, Ti-412 (~750MPa 0.2%YS) was also tested towards the end of the project and helped to further elucidate understanding of the fatigue characteristics of the two alloys. Of interest was the strong HCF response displayed relative to the monotonic tensile strength. As well as the investigation into the crack initiation mechanisms, an assessment of crack propagation across a range of microstructural conditions was carried out on Ti-407 material.

scholarly journals Effect of Sandblasting on Low and High-Cycle Fatigue Behaviour after Mechanical Cutting of a Twinning-Induced Plasticity Steel

2018 ◽  
Vol 165 ◽  
pp. 18002
Author(s):  
Antoni Lara ◽  
Mercè Roca ◽  
Sergi Parareda ◽  
Núria Cuadrado ◽  
Jessica Calvo ◽  
...  
Keyword(s):  
High Cycle Fatigue ◽  
Twip Steel ◽  
Low Cycle Fatigue ◽  
Load Ratio ◽  
Fatigue Behaviour ◽  
Cycle Fatigue ◽  
High Manganese ◽  
Amplitude Control ◽  
Cut Edge ◽  
Mechanical Cutting

In the last years, car bodies are increasingly made with new advanced high-strength steels, for both lightweighting and safety purposes. Among these new steels, high-manganese or TWIP steels exhibit a promising combination of strength and toughness, arising from the austenitic structure, strengthened by C, and from the twinning induced plasticity effect. Mechanical cutting such as punching or shearing is widely used for the manufacturing of car body components. This method is known to bring about a very clear plastic deformation and therefore causes a significant increase of mechanical stress and micro-hardness in the zone adjacent to the cut edge. To improve the cut edge quality, surface treatments, such as sandblasting, are often used. This surface treatment generates a compressive residual stress layer in the subsurface region. The monotonic tensile properties and deformation mechanisms of these steels have been extensively studied, as well as the effect of grain size and distribution and chemical composition on fatigue behaviour; however, there is not so much documentation about the fatigue performance of these steels cut using different strategies. Thus, the aim of this work is to analyse the fatigue behaviour of a TWIP steel after mechanical cutting with and without sandblasting in Low and High-Cycle Fatigue regimes. The fatigue behaviour has been determined at room temperature with tensile samples tested with a load ratio of 0.1 and load amplitude control to analyse High-Cycle Fatigue behaviour; and a load ratio of -1 and strain amplitude control to determine the Low-Cycle Fatigue behaviour. Samples were cut by shearing with a clearance value of 5%. Afterwards, a part of the cut specimens were manually blasted using glass microspheres of 40 to 95 microns of diameter as abrasive media. The results show a beneficial effect of the sandblasting process in fatigue behaviour in both regimes, load amplitude control (HCF) and strain amplitude control (LCF) tests, when these magnitudes are low, while no significant differences are observed with higher amplitudes. low-cycle fatigue, high-cycle fatigue, mechanical cutting, sandblasting, high manganese steel, TWIP steel

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