Comparative Study of the Additional Hardening Effects of Three Structural Steels

2006 ◽  
Vol 514-516 ◽  
pp. 534-538
Author(s):  
Luís G. Reis ◽  
Bin Li ◽  
Manuel de Freitas
Keyword(s):  
Low Cycle Fatigue ◽  
Testing Machine ◽  
Great Influence ◽  
Structural Steels ◽  
Loading Path ◽  
Multiaxial Loading ◽  
Cycle Fatigue ◽  
Proportional Loading ◽  
Loading Paths ◽  
Additional Hardening

For a safe and reliable design of components, it is needed to study the effects of multiaxial loading and particularly the non-proportional loadings on the fatigue damage. The objective of this paper is to evaluate and compare the additional hardening effects of proportional and non-proportional loading paths. Low-cycle fatigue behaviour of three structural steels: CK45 (ferritic-perlitic microstructure) normalized steel, 42CrMo4 (bainitic microstructure) quenched and tempered steel and stainless steel (austenitic microstructure) X10CrNiS 18 9 are studied under different proportional and non-proportional loading paths and different levels. A series of tests of biaxial low-cycle fatigue composed of tension/compression with static or cyclic torsion were carried out on a biaxial servo-hydraulic testing machine Instron 8088. The experiments showed that the three materials studied have very different additional hardening behaviour, under multiaxial cyclic loading paths. The local cyclic stress/strain states are influenced by the multiaxial loading paths due to interactions between the normal stress and shear stress during cyclic plastic deformation. The microstructure is an important key and has a great influence on the additional hardening. The additional hardening effect is dependent of the loading path and also the intensity of the loading.

Fatigue Characteristic and Dislocation Substructure of A356 Casting Alloy under Multi-Axial Cyclic Loadings

2011 ◽  
Vol 306-307 ◽  
pp. 489-495 ◽  
Author(s):  
De Feng Mo ◽  
Guo Qiu He ◽  
Da Fu Liu ◽  
Zheng Yu Zhu
Keyword(s):  
Fatigue Life ◽  
Fatigue Failure ◽  
Low Cycle Fatigue ◽  
Cyclic Hardening ◽  
Fatigue Tests ◽  
Loading Path ◽  
Loading Paths ◽  
Casting Alloys ◽  
The Difference ◽  
Additional Hardening

Mechanical fatigue tests were conducted on specimens of A356-T6 casting alloys under multi-axial cyclic loadings with 5 loading paths (proportional, circular, square, diamond, and ellipse path). Optical microscopy and TEM were used to examine both undeformed and fatigue failure specimens. It is shown that undeformed material has coarse microstructure with low density of dislocation. Under every loading path, cyclic hardening dominates the whole fatigue process. Additional hardening is found in this casting material, but the rate and extent of cyclic hardening and additional hardening are quite dependent on particular loading paths. Various dislocation substructures are observed in the specimens including specimens fatigued to 20 cycles and fatigue failure specimens. While these dislocation substructures are determined by the moving ability of dislocation and interactions between dislocation and particles. Low cycle fatigue life is sensitive to the difference of loading paths, and the fatigue life increases as the extent of cyclic hardening decreases.

Crack mode and life of Ti-6Al-4V under multiaxial low cycle fatigue

2015 ◽  
Author(s):  
Takamoto Itoh ◽  
Masao Sakane ◽  
Takahiro Morishita ◽  
Hiroshi Nakamura ◽  
Masahiro Takanashi
Keyword(s):  
Hollow Cylinder ◽  
Stress Ratio ◽  
Biaxial Loading ◽  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
Testing Machine ◽  
Multiaxial Fatigue ◽  
Cycle Fatigue ◽  
Loading Test ◽  
Failure Life

This paper studies multiaxial low cycle fatigue crack mode and failure life of Ti-6Al-4V. Stress controlled fatigue tests were carried out using a hollow cylinder specimen under multiaxial loadings of ?=0, 0.4, 0.5 and 1 of which stress ratio R=0 at room temperature. ? is a principal stress ratio and is defined as ?=sigmaII/sigmaI, where sigmaI and sigmaII are principal stresses of which absolute values take the largest and middle ones, respectively. Here, the test at ?=0 is a uniaxial loading test and that at ?=1 an equi-biaxial loading test. A testing machine employed is a newly developed multiaxial fatigue testing machine which can apply push-pull and reversed torsion loadings with inner pressure onto the hollow cylinder specimen. Based on the obtained results, this study discusses evaluation of the biaxial low cycle fatigue life and crack mode. Failure life is reduced with increasing ? induced by cyclic ratcheting. The crack mode is affected by the surface condition of cut-machining and the failure life depends on the crack mode in the multiaxial loading largely.

scholarly journals 104 Multiaxial Low Cycle Fatigue Life of Ti-6Al-4V under Non-proportional Loading

2009 ◽  
Vol 2009.46 (0) ◽  
pp. 7-8
Author(s):  
Yuuta SHIMIZU ◽  
Takamoto ITOH ◽  
Hiroshi NAKAMURA ◽  
Masahiro TAKANASHI
Keyword(s):  
Fatigue Life ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Proportional Loading

scholarly journals New research findings on non-proportional low cycle fatigue

2019 ◽  
Vol 300 ◽  
pp. 08003
Author(s):  
Anghel Cernescu ◽  
Rhys Pullin
Keyword(s):  
Low Cycle Fatigue ◽  
Strain Range ◽  
Material Constant ◽  
Multiaxial Fatigue ◽  
Shear Strain Rate ◽  
Proportional Loading ◽  
New Research ◽  
Life Predictions ◽  
Multiaxial Loadings ◽  
Additional Hardening

One of the challenges regarding multiaxial fatigue damage predictions is non-proportional loading. Relevant studies have shown that these multiaxial loadings cause significant additional hardening and reduction in durability due to non-proportionality. Fatigue life predictions due to non-proportional loadings are based on an equivalent non-proportional strain range that considers a material constant related to additional hardening and a non-proportionality factor. In this paper an analysis of the non-proportional factor for three multiaxial loadings forming a square in γ/√3 – ε coordinates is carried out. One of the observations revealed by this analysis is the sensitivity of the non-proportional factor to variable shear strain rate.

The Biaxial Stress-Strain Curves of Sheet Metals

2010 ◽  
Vol 44-47 ◽  
pp. 2519-2523
Author(s):  
Hai Bo Wang ◽  
Min Wan ◽  
Yu Yan ◽  
Xiang Dong Wu
Keyword(s):  
Transverse Direction ◽  
Biaxial Loading ◽  
Testing Machine ◽  
Rolling Direction ◽  
Biaxial Stress ◽  
Loading Path ◽  
Sheet Metals ◽  
Stress Strain ◽  
Loading Paths ◽  
Loading Ratio

Biaxial tensile tests of 5754O aluminum alloy sheet and B170P1 steel sheet were performed under linear loading paths with cruciform specimens and a biaxial loading testing machine. The stress-strain curves under different loading paths were obtained. It is found that the loading path has a significant influence on the stress-strain curves, i.e., the stress-strain curves vary with the loading path. The stress-strain curves in the rolling direction become higher with the decrease of the loading ratio (the ratio of the load along the rolling direction to that along the transverse direction) from 4:0 to 4:4. Meanwhile the stress-strain curves in the transverse direction become lower with the decrease of the loading ratio from 4:4 to 0:4. Based on Yld2000-2d yield criterion, the experimental phenomena of the two kinds of sheet metals under biaxial tension were explained theoretically.

Low Cycle Fatigue Test of Lead Free Solders Using Small Sized Specimen

2017 ◽  
Vol 734 ◽  
pp. 194-201 ◽  
Author(s):  
Yutaka Konishi ◽  
Takamoto Itoh ◽  
Masao Sakane ◽  
Fumio Ogawa ◽  
Hideyuki Kanayama
Keyword(s):  
Fatigue Testing ◽  
Low Cycle Fatigue ◽  
Testing Machine ◽  
Strain Range ◽  
Fatigue Tests ◽  
Lead Free ◽  
Cycle Fatigue ◽  
Bulk Specimen ◽  
Free Solder ◽  
Lead Free Solders

This paper investigates the fatigue results in low cycle fatigue region obtained from a miniaturized specimen having a 6mm gage length, 3mm diameter and 55mm total length. Fatigue tests were performed for two type lead-free solders using horizontal-type electrical servo hydraulic push-pull fatigue testing machine. Materials employed were Sn-3.0Ag-0.5Cu and Sn-5Sb. The results from Sn-3.0Ag-0.5Cu were compared with those obtained using a bulk specimen in a previous study. Relationship between strain range and number of cycles to failure of the small-sized specimen agreed with those of the bulk specimens. The testing techniques are applicable to Sn-5Sb following the Manson-Coffin law. These results confirm that the testing technique proposed here, using small-sized specimen, is suitable to get fruitful fatigue data for lead-free solder compounds.

Yield Surface and Complex Loading Path Simulation of a Duplex Stainless Steel Using a Bi-Phase Polycrystalline Model

2007 ◽  
Vol 567-568 ◽  
pp. 141-144 ◽  
Author(s):  
Pierre Evrard ◽  
Veronique Aubin ◽  
Suzanne Degallaix ◽  
Djimedo Kondo
Keyword(s):  
Stainless Steel ◽  
Uniaxial Tension ◽  
Compression Test ◽  
Plastic Anisotropy ◽  
Constant Strain Rate ◽  
Loading Path ◽  
Model Parameters ◽  
Proportional Loading ◽  
Loading Paths ◽  
Polycrystalline Model

In order to model the elasto-viscoplastic behaviour of an austenitic-ferritic stainless steel, the model initially developed by Cailletaud-Pilvin [1] [2] and used for modeling single-phase polycrystalline steel is extended in order to take into account the bi-phased character of a duplex steel. Two concentration laws and two local constitutive laws, based on the crystallographic slips and the dislocation densities, are thus simultaneously considered. The model parameters are identified by an inverse method. Simple tests among which tension test at constant strain rate and at different strain rates and uniaxial tension-compression test are used during the identification step. The predictive capabilities of the polycrystalline model are tested for non-proportional loading paths. It is shown that the model reproduces the over-hardening experimentally observed for this kind of loading paths. Then, yield surfaces are simulated during a uniaxial tension-compression test: it is shown that the distortion (i.e. plastic anisotropy induced by loading path) is correctly described.

Sign in / Sign up

Export Citation Format

Share Document