Eutectic cell wall morphology and tensile embrittlement in ferritic spheroidal graphite cast iron

Shiao, F. T.; Lui, Truan-Sheng; Chen, Lihui; Chen, S. F.

doi:10.1007/s11661-999-0176-8

Cited by 11 publications

(11 citation statements)

References 5 publications

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“…3.1 Effect of solidification cooling rate on the variation of eutectic cell morphologies From previous investigations, [8][9][10] it is clear that the tensile properties of SG cast iron at elevated temperatures are strongly dependent on the feature of the eutectic cell morphology. Figure 3 shows the electrochemically-etched ferritic SG cast iron, the morphology of the eutectic cell wall is marked by arrows.…”

Section: Resultsmentioning

confidence: 99%

“…5. Worthy of notice is the specimen tensile tested at 673 K. 9,13,14) For these specimens, the intergranular fracture surface varied according to the eutectic cell wall region size. On the other hand, only cleavage and dimple fracture pattern could be observed when the specimen was tensile tested at room temperature.…”

Section: 2mentioning

confidence: 99%

“…This was the dominant factor causing a deterioration in tensile properties after the specimen suffered a cyclic heating process. [8][9][10][11][12][13][14] In this case, in spite of the tensile tested be performed at room temperature, ductility deterioration caused by intergranular fracture was identified. This raises the questions of how the dispersed MgO inclusions affect the intergranular fracture behavior, and the effect of the eutectic cell wall morphology during these severe cyclic heating/ cooling processes on reliability.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Microstructural Refinement on Ductility Deterioration of High Silicon Ferritic Spheroidal Graphite Cast Iron Caused by Cyclic Heating

2003

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This investigation applies cyclic heating and cooling to elucidate the effect of microstructural refinement on the tensile elongation deterioration of ferritic spheroidal graphite cast iron. In order to eliminate the oxidation factor, the cyclic heating/cooling test was performed in a 1:33 $ 0:133 Pa ambient vacuum atmosphere with cyclic heating at a maximum temperature of 1023 K. Severe embrittlement accompanied by intergranular fracture occurred after the ferritic spheroidal graphite cast iron was subjected to a certain number of heating and cooling cycles. A fair amount of inevitable inclusion particles were found to agglomerate in the eutectic cell boundary region, and so the cyclic heating induced embrittlement can be recognized to be strongly dependent on the solidification cooling rate of the materials. Based on experimental evidence, the cracking evolution can be divided into three steps: (1) crack initiation from the vicinity of the eutectic cell boundary at the surface, (2) crack linking and major crack formation, and (3) major crack inward extension. Cyclic heating cracks are mainly initiated at the eutectic cell boundary where a fair amount of MgO inclusions dispersed, and consequently propagated along the annealed eutectic cell boundary. While investigating the plastic deformation behaviors around the above mentioned MgO inclusions pertaining to the crack initiation and crack propagation, typical etch pit evidence was observed in the vicinity of the cell boundary area.

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Section: Resultsmentioning

confidence: 99%

Section: 2mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of Microstructural Refinement on Ductility Deterioration of High Silicon Ferritic Spheroidal Graphite Cast Iron Caused by Cyclic Heating

2003

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“…Before SAM analysis, the specimens were machined with notch prior to perform insitu impact tested at À50 C in a SAM vacuum chamber at 10 À10 Pa. Figure 1 shows that little differences in average graphite nodule size ( d d g ), and ferrite grain size ( d d f ) are observed with increasing silicon content. Figures 1(c) and (d) reveal the distribution of the inclusion particles around the eutectic cell walls, 6,7) the area of clustered inclusions can be identified by electrochemical etching. Compare to other samples, the 2.9Si specimen shows the least amount of inclusion particles in the eutectic cell wall regions, however the degree of inclusion clustering become significant as increasing silicon concentration.…”

Section: Methodsmentioning

confidence: 99%

Effect of Silicon Content on Intergranular Embrittlement of Ferritic Spheroidal Graphite Cast Iron Suffered from Cyclic Heating

2003

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The effect of silicon content on intergranular embrittlement of ferritic spheroidal graphite cast irons after suffer a certain number of thermal cycles is investigated. The tensile elongation tends to increase with the number of thermal cycles, and increased silicon content leads to eventual embrittlement. The fracture surface of a 2.9Si specimen changes from dimple pattern feature to intergranular fracture, whereas the fracture surfaces of both 4.0Si and 4.3Si specimens change from the brittle cleavage to intergranular fracture that following with increasing the number of thermal cycles. The intergranular cracking path will initiate and propagate through the eutectic cell boundaries due to the presence of microsegregated inclusions that clustered in the eutectic cell boundary region. These inclusions are oxides that mainly contain magnesium, phosphorus and cerium. Experimental analysis detected that the magnesium elements not only segregated in the vicinity of eutectic cell boundaries, but also the annealed ferritic grain boundaries. However the embrittlement resulted from cyclic heating is strongly dependent on the morphology of clustered inclusions and is pertaining to the variation of silicon content. The observed magnesium-containing inclusions located in the central region of the matrix may profoundly affect the overall tensile fracture behavior of heat resistant used SG cast irons.

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“…The IE damage mechanism was studied by several authors [2][3][4][5][6]. Nevertheless there is no clear explanation for this phenomenon.…”

Section: Introductionmentioning

confidence: 99%

Towards a temperature dependent and probabilistic lifetime concept for nodular ductile cast iron materials undergoing isothermal and thermo-mechanical fatigue

2018

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Abstract. In this investigation, the fatigue behaviour of a ductile cast iron with high content of silicon and molybdenum, was experimentally characterized by performing isothermal low cycle fatigue (LCF) tests as well as out-of-phase thermomechanical fatigue (OPTMF) tests within the temperature range RT -500 °C. The studied material shows an embrittlement at temperatures nearby 400 °C. A possible explanation for the observed lifetime reduction is intergranular embrittlement (IE). A mechanism based lifetime model is proposed for assessing the lifetime. The model is based on the assumption that the crack advance per cycle is correlated with the cyclic crack tip opening displacement (∆CTOD) attributed to the crack tip blunting caused by accumulation of plastic and creep deformations ahead of the crack tip. Intergranular embrittlement is accounted for by introducing a temperature and strain rate dependent prefactor in the crack growth law, which only acts in a certain temperature range. The model is calibrated for a GJS material and successfully applied to predict the lifetime of this material when undergoing isothermal and non-isothermal mechanical loadings. A probabilistic interpretation of the scatter of the investigated material is presented in conjunction with the random nature of the initial defect size distribution.

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Eutectic cell wall morphology and tensile embrittlement in ferritic spheroidal graphite cast iron

Cited by 11 publications

References 5 publications

Effect of Microstructural Refinement on Ductility Deterioration of High Silicon Ferritic Spheroidal Graphite Cast Iron Caused by Cyclic Heating

Effect of Microstructural Refinement on Ductility Deterioration of High Silicon Ferritic Spheroidal Graphite Cast Iron Caused by Cyclic Heating

Effect of Silicon Content on Intergranular Embrittlement of Ferritic Spheroidal Graphite Cast Iron Suffered from Cyclic Heating

Towards a temperature dependent and probabilistic lifetime concept for nodular ductile cast iron materials undergoing isothermal and thermo-mechanical fatigue

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