Microstructural effects on fatigue crack growth in a low carbon steel

Suzuki, Hideji; McEvily, A.J.

doi:10.1007/bf02697075

Cited by 147 publications

(42 citation statements)

References 15 publications

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“…As is characteristic with duplex microstructures (14,15,(20)(21)(22)(23)(24), crack extension was not confined to either one of the two phases. However, crack paths were distinctly more tortuous in the Fe/2Si/0.1C steel, suggesting that the superior near-threshold fatigue resistance was again a consequence of enhanced roughness-induced closure.…”

Section: Introductionmentioning

confidence: 79%

“…McEvily and co-workers (14,15) who developed two different duplex microstructures in an AISI 1018 steel; one where a continuous ferrite matrix encapsulated islands of martensite (termed FEM or Type A in McEvily and co-workers' terminology (14,15}), and the other where a continuous martensitic phase encapsulated islands of ferrite (termed MEF or Type B).…”

Section: Introductionmentioning

confidence: 99%

“…Based on studies which identified the fatigue limit in such structures as the stress intensity at which micro-cracks, initiated in the softer ferrite phase, were arrested in the harder martensite phase (21), Kunio, Yamada and co-workers (22,23) found that duplex microstructures in AISI 1023, 1025 and low alloy steels had only a minimal influence on short crack thresholds. For example, by comparing MEF and FEM structures in rotating bending tests on mild steel at R = -1, these authors report that the MEF microstructures, which were shown to have' 75 pct higher threshold ~K values for o long cracks (i.e., 14 MPalm versus 8 MPalm) (14), yielded essentially identical threshold values (i.e .• between 7.4 and 7.9 MPalm) when measured on short cracks between 0.5 and 1 mm in length. -4-Although duplex ferritic-martensitic microstructures appear promising from the point of view of designing alloys with improved resistance to high cycle fatigue crack growth, the results to date are often difficult to compare.…”

Section: Introductionmentioning

confidence: 99%

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Fatigue crack propagation in dual-phase steels: Effects of ferritic-martensitic microstructures on crack path morphology

1984

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LBL-16264Characteristics of fatigue crack propagation in dual-phase steels have been investigated in a high purity Fe-2Si-0.lC steel with the objective of developing ferritic-martensitic microstructures with maximum resistance to fatigue crack extension whilst maintaining high strength levels. A wide range of crack growth rates has been examined, from ~ 10-8 to 10-3 mm/cycle, in a series of duplex microstructures of comparable yield strength and prior austenite grain size where intercritical heat-treatments were used to vary the proportion, morphology and distribution of the ferrite and martensite phases. Results of fatigue crack propagation tests, conducted on "long cracks" in room temperature moist air environments, revealed a very large influence of microstructure over the entire spectrum of growth rates at low load ratios. Similar trends were observed at high load ratio, although the extent of the microstructural effects on crack growth behavior was V. B. DUTTA is Graduate Student Research

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Section: Introductionmentioning

confidence: 79%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Fatigue crack propagation in dual-phase steels: Effects of ferritic-martensitic microstructures on crack path morphology

1984

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“…Several researchers have reported the dependence of long crack growth behavior and fatigue threshold stress intensity range on microstructure of dual-phase steels. [6][7][8][9][10][11] However the effects of microstructural morphology and prestraining on short crack growth behavior have not been fully explored because of experimental difficulties.…”

Section: Introductionmentioning

confidence: 99%

Influence of Microstructural Morphology and Prestraining on Short Fatigue Crack Propagation in Dual-phase Steels

et al. 2001

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The ferrite-martensite dual phase (DP) steels offer a better combination of strength and ductility than other conventional steels with equivalent static strength which are generally used in the automobile industry. The continuous martensite phase in DP steels seems to play an important role in determining fatigue properties and be a key factor to gain a higher resistance to fatigue. Additionally it is very important from a practical point of view to improve the fatigue properties after prestraining or cold working. The effects of microstructural morphology and prestraining on the propagation behavior of short fatigue cracks in DP steels were investigated by the in-situ observation in a scanning electron microscope. The material with martensites continuously surrounding individual ferrites exhibited a higher fatigue strength and longer fatigue life than those of the material with martensite phase dispersed in the ferrite matrix. Cold rolling prior to fatigue testing resulted in a decrease of fatigue life for both materials, especially an extreme decrease for the martensite-dispersed material. It was found that the fatigue crack propagation was sensitive to microstructural morphology and prestraining only in the small crack within a range of approximately 250 mm and the propagation life of this region governed the total fatigue life.

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“…This can be achieved by appropriate heat treatment [1][2][3][4]. Under repeated stresses, microscopic plasticity introduces nonhomogeneity in the dual-phase steel on account of the dissimilar physical/ mechanical properties of the martensite and ferrite in addition to their size and distribution.…”

Section: Introductionmentioning

confidence: 99%

Fatigue crack growth rate in ferrite-martensite dual-phase steel

1992

International Journal of Fatigue

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An empirical study is made on the fatigue crack growth rate in ferrite-martensite dual-phase (FMDP) steel. Particular attention is given to the effect of ferrite content in the range of 24.2% to 41.5% where good fatigue resistance was found at 33.8%. Variations in ferrite content did not affect the crack growth rate da/dN when plotted against the effective stress intensity factor range AK~I ~ which was assumed to follow a linear relation with the crack tip stress intensity factor range AK. A high AK~f~. corresponds to uniformly distributed small size ferrite and martensite. No other appreciable correlation could be related to the microstructure morphology of the FMDP steel. The closure stress intensity factor K d, however, is affected by the ferrite content with K,q/Km~,× reaching a maximum value of 0.7. In general, crack growth followed the interphase between the martensite and ferrite.Dividing the fatigue crack growth process into Stage I and It where the former would be highly sensitive to changes in AK and the latter would increase with AK depending on the R = Crmi n/Om~x ratio. The same data when correlated with the strain energy density factor range AS showed negligible dependence on mean stress or R ratio for Stage I crack growth. A parameter a involving the ratio of ultimate stress to yield stress, percent reduction of area and R is introduced for Stage II crack growth so that the da/dN data for different R would collapse onto a single curve with a narrow scatter band when ploned against aAS.

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Microstructural effects on fatigue crack growth in a low carbon steel

Cited by 147 publications

References 15 publications

Fatigue crack propagation in dual-phase steels: Effects of ferritic-martensitic microstructures on crack path morphology

Fatigue crack propagation in dual-phase steels: Effects of ferritic-martensitic microstructures on crack path morphology

Influence of Microstructural Morphology and Prestraining on Short Fatigue Crack Propagation in Dual-phase Steels

Fatigue crack growth rate in ferrite-martensite dual-phase steel

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