Distribution of the Inclusion Particles in Ferritic Spheroidal Graphite Cast Irons

Shiao, F. T.; Lui, Truan-Sheng; Chen, L. H.

doi:10.2320/matertrans1989.39.1033

Cited by 7 publications

(3 citation statements)

References 6 publications

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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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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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“…However, inclusion particles were thought by many researchers to be detrimental to mechanical properties of steels, because they acted as the sites for forming micro-voids resulting in cleavage cracks in the process of tensile, cyclic loading or impact testing. 3,6,7) Despite the controversy, the above studies acknowledged the correlations of inclusion particles and the microstructures in commercial steels. In fact, the mechanical properties of ADI are also affected by its matrix microstructure.…”

Section: Introductionmentioning

confidence: 99%

“…These strongly oxidizing elements tend to combine with dissolved oxygen, sulfur or other finely divided oxides suspended in the molten iron and form inclusion particles. [1][2][3] The role of inclusion particles in the performance of mechanical properties has been a controversial subject. Shim et al 4) demonstrated that inclusion particles dispersed in the austempering of medium carbon steels provided potential sites for the heterogeneous nucleation of ferrite during the austenite-ferrite transformation.…”

Section: Introductionmentioning

confidence: 99%

Effects of Inclusion Particles on the Microstructure and Mechanical Properties of High Strength Austempered Ductile Iron

Shih

2003

Mater. Trans.

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Effects of inclusion particles on the microstructure and mechanical properties of high strength austempered ductile iron (ADI) were investigated in this study. Inclusion particles, especially when their sizes are less than 5 mm, were mostly found in intercellular regions. Whether an inclusion particle can induce the formation of acicular ferrite depends on Mn segregation. In intercellular region, acicular ferrite was hard to form in the vicinity of inclusion particles due to (1) serious Mn segregation, and/or (2) the Mg-enriched inclusions here in halo-like. Consequently the surrounding austenite remained to be blocky type after austempering treatment. The fatigue life cycles of ADIs were affected by the particle counts and the microstructure. Increasing the count of fine inclusions along with the effect of Mn segregation deteriorated the fatigue life and elongation of high strength ADIs.

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Effect of nodularity on resonant vibration fracture behavior in upper bainitic and ferritic cast irons

Lin

Lui

Chen

2000

Metall Mater Trans A

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This work examines resonant vibration fatigue fracture behavior. According to those results, the region I section of the D-N curve (deflection amplitude vs number of vibration cycles) declined with decreasing graphite nodularity or a changing of the matrix to a bainitic structure. Resonant vibration fatigue cracks were often initiated at graphite particles on the surface and grew into the body of the specimen. Initiation and propagation of these cracks were promoted by lowering the graphite nodularity, but no significant difference in deflection amplitude was observed with a bainitic or ferritic matrix microstructure. Bainitic cast iron specimens proved to have a higher initial deflection amplitude and would simply drop almost without displaying region I as the cycle numbers of vibration increased.

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Distribution of the Inclusion Particles in Ferritic Spheroidal Graphite Cast Irons

Cited by 7 publications

References 6 publications

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

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

Effects of Inclusion Particles on the Microstructure and Mechanical Properties of High Strength Austempered Ductile Iron

Effect of nodularity on resonant vibration fracture behavior in upper bainitic and ferritic cast irons

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