Influence of section size on dual phase ADI microstructure and properties: Comparison with fully ferritic and fully ausferritic matrices

Basso, Alejandro Daniel; Martinez, Rodolfo A.; Sikora, Jorge Antonio

doi:10.1179/174328408x365784

Cited by 23 publications

(42 citation statements)

References 12 publications

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“…As already defined by the authors in previous works, [4][5][6] the lower critical temperature (Lct) is the lower temperature at which the austenite transformation starts (detected by the presence of less than 5% of martensite after quenching). The upper critical temperature (Uct), in turn, is defined as the temperature at which a matrix with over 98% of martensite is detected after quenching the samples held at such temperature.…”

Section: Metallographic Characterization Of the Intercritical Intervamentioning

confidence: 97%

“…The methodology employed to establish the intercritical interval for a specific alloy has been detailed in previous works, [4][5][6] and is herein summarized as follows: several specimens of each melt 12 mm in diameter × 25 mm in length were subjected to annealing thermal cycles consisting of: a) austenitizing at 900°C for 3 hours, b) cooling down to 740°C inside the furnace, c) holding at 740°C for 10 hours, and d) cooling down to room temperature inside the furnace. To establish the intercritical interval for each melt, after annealing, the samples were subjected to thermal cycles involving austenitizing stages ranging from 730°C to 900°C at steps of 10°C.…”

Section: Heat Treatmentsmentioning

confidence: 99%

“…This improvement is explained by the novelty of this DI microstructure, which is composed of different amounts of free (or allotriomorphic) ferrite and ausferrite (ADI regular structure). [1][2][3][4][5][6][7][8][9][10][11] Special thermal cycles have been developed by different researchers in order to obtain Dual Phase ADI. One of them has been advanced and used by Kilicli et al 7,8) and Basso et al [4][5][6] It consists in subjecting fully ferritic DI parts to an incomplete austenitization stage, at different temperatures within the intercritical interval of the Fe-C-Si diagram (see Fig.…”

Section: Introduccionmentioning

confidence: 99%

See 2 more Smart Citations

High Silicon Ductile Iron: Possible Uses in the Production of Parts with ^|^ldquo;Dual Phase ADI^|^rdquo; Microstructure

et al. 2012

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The aim of this paper is to study the advantages and disadvantages of using high silicon ductile iron to produce cast parts with "Dual Phase ADI" microstructure. In this study, four ductile irons with different percentages of silicon: 2.4, 3.1, 3.5, and 4.2%, respectively, were used. Samples from each cast were subjected to heat treatment in order to determine the intercritical interval. Significant increase in the upper and lower critical temperatures was found as the amount of silicon incremented. However, the difference between the lower and upper critical temperatures (intercritical interval amplitude) remained nearly constant for all ductile irons.The materials were metallographically and mechanically characterized in the as-cast conditions and after full annealing heat treatments. Tensile, hardness and impact properties were determined as a function of the silicon level.The results suggest that high silicon ductile iron (Si content ranging from 3.0 to 3.6%) can be used in the manufacture of cast parts with "Dual Phase ADI" microstructures, yielding undeniable advantages in the production process if compared to low and medium silicon ductile irons.

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Section: Metallographic Characterization Of the Intercritical Intervamentioning

confidence: 97%

Section: Heat Treatmentsmentioning

confidence: 99%

Section: Introduccionmentioning

confidence: 99%

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High Silicon Ductile Iron: Possible Uses in the Production of Parts with ^|^ldquo;Dual Phase ADI^|^rdquo; Microstructure

et al. 2012

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“…The matrix of a dual phase ADI is composed by ausferrite (as in regular ADI microstructure) and free or allotriomorphic ferrite, in an attempt to combine the high tensile strength and toughness of the ausferrite with the high ductility of ferrite. [15][16][17][18][19][20][21][22][23][24] Different methodologies have been applied to obtain dual phase microstructures. [15][16][17][18][19][20] The simplest method seems to be that described by Basso et al 21,22) and Kilicli et al, 23,24) which consists of an incomplete austenization stage at temperatures within the intercritical interval, where austenite (γ) ferrite (α) and graphite (Gr) coexist (Fig.…”

Section: Introductionmentioning

confidence: 99%

Development and Characterization of a New Type of Ductile Iron with a Novel Multi-phase Microstructure

et al. 2011

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Over the last few years two new types of Ductile Iron (DI) have been developed based on Austempered DI (ADI), called Dual Phase ADI and Carbidic ADI (CADI), respectively. In the light of the experience acquired when studying these DI variants, the authors found motivating the possibility of obtaining a new type of multi-phase DI (MPDI), combining their main microstructural characteristics. A DI melt alloyed with 2%Cr, exhibiting free carbides and a pearlitic matrix in its as-cast condition, was used. The upper (UCT) and lower (LCT) critical temperatures of the Fe-C-Si equilibrium diagram region, where ferrite (α), austenite (γ) and graphite (Gr) coexist (called "intercritical interval"), were determined by heat treatment and microstructural analysis on samples previously annealed. Carbides stability was studied, and its dissolution was found to be negligible. It was possible to obtain free or allotriomorphic ferrite and austenite by isothermal austenitizing at temperatures within the intercritical interval, and then transform the remaining austenite into ausferrite after an austempering step. Therefore, multi-phase microstructures composed of graphite nodules, free carbides, free ferrite and ausferrite were obtained. The possibility of obtaining MPDI directly from the as-cast structure was also analyzed, and it was found that very similar microstructures to those previously annealed can be obtained by austenitizing samples at the same temperature range. These results proved that the pearlite → austenite transformation kinetics is rapid, as it took only one hour for the transformation to occur.

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“…An alternative is the development of austempered ductile iron (ADI) alloys where alloying methods and subsequent heat treatments are required to form a bainitic or ausferritic matrix. [4][5][6][7] Owing to the extra costs related to ADI, several investigations have been devoted to improve the mechanical properties obtained from as cast cast irons. In this line, silicon strengthened DI alloys become an interesting group of materials due to their good strength/elongation ratio when comparing to the standard DI grades.…”

Section: Introductionmentioning

confidence: 99%

As cast high silicon ductile irons with optimised mechanical properties and remarkable fatigue properties

Torre

Loizaga

Lacaze

et al. 2014

Materials Science and Technology

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To cite this version:Urko de La Torre, Aitor Loizaga, Jacques Lacaze, Jon Sertucha. As cast high silicon ductile irons with optimised mechanical properties and remarkable fatigue properties. Materials Science and Technology, Maney Publishing, 2014, vol. 30 (n°12) The present work shows a comparative study regarding the mechanical properties of 25 as cast ferritic ductile iron alloys, nine of them with silicon contents higher than 3?00% and carbon contents lower than 3?60%. In a first step, different carbon equivalent values have been used in order to analyse the effect of this parameter on the mechanical properties. After this comparative analysis, the composition ranges C53?30-3?40 wt-% and Si53?75-3?80 wt-% have been selected as the most proper ones to optimise the tensile and impact properties among the high silicon ductile iron alloys. Finally, a second study was carried out to compare the tensile and fatigue properties of the optimised high silicon alloy with the corresponding ones obtained from an EN GJS 400-18-LT grade alloy with low silicon content. Although the room temperature impact values obtained from the high silicon ductile iron are lower than 6 J cm 22 , the measured fatigue limit of this alloy (358 MPa) is clearly higher than the one obtained from the low silicon cast iron (170 MPa). A discussion about the benefits and advantages of the high silicon alloy is included.

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Influence of section size on dual phase ADI microstructure and properties: Comparison with fully ferritic and fully ausferritic matrices

Cited by 23 publications

References 12 publications

High Silicon Ductile Iron: Possible Uses in the Production of Parts with ^|^ldquo;Dual Phase ADI^|^rdquo; Microstructure

High Silicon Ductile Iron: Possible Uses in the Production of Parts with ^|^ldquo;Dual Phase ADI^|^rdquo; Microstructure

Development and Characterization of a New Type of Ductile Iron with a Novel Multi-phase Microstructure

As cast high silicon ductile irons with optimised mechanical properties and remarkable fatigue properties

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