Fracture Micromechanisms Evaluation of High-Strength Cast Irons Under Thermomechanical Fatigue Conditions

Bon, Douglas; Ferreira, Marcio Henrique; Filho, Waldek Wladimir Bose; Guesser, Wilson Luiz

doi:10.1007/s40962-019-00399-w

Cited by 9 publications

(6 citation statements)

References 10 publications

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“…Through the results from this work and also from other authors [12,15,16], it was concluded that the connectivity of graphite cells, their size and distribution, directly affects the compacted cast iron properties, such as mechanical strength, fatigue and thermal conductivity. As the graphite cells are crucial for the cast iron properties, the results obtained for the CGI500 showed an enhanced mechanical strength and OP-TMF resistance in relation to the CGI450.…”

Section: Discussionsupporting

confidence: 56%

“…The CGI 500 shows a quite similar microstructure, see Figure 4a, with 9.6% of type III-IV graphite particles with 24% nodularity. It is observed also, that the graphite cells are smaller and less connected (CGI 450 = 433μm and CGI500 = 337μm [12]. The matrix, Figure 4b, are mainly composed of pearlite.…”

Section: Resultsmentioning

confidence: 88%

“…As shown in Figure 8 and Figure 9a for the CGI 500, cracks start from graphite particles at or close to the specimen surface, with crack growth through the pearlitic matrix by fatigue striation (Figure 9b) with a cleavage appearance (grey phase), and by graphite matrix interface (black phase), until final failure by mixture of ductile and cleavage modes [12,14,15]. The cavities or rounded features observed on the fracture surface are voids left by the graphite or from the graphite that stayed in the other half [14,16].…”

Section: Resultsmentioning

confidence: 99%

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Thermomechanical fatigue behavior of CGI 450 and CGI 500 cast irons

Ferreira¹,

Bon²,

Bose³

et al. 2022

Tecnol. Metal. Mater. Min.

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The vermicular cast iron grade 450 is widely used in engineering applications, primarily by the automotive industry in the fabrication of internal combustion engines. However, in recent years, the vermicular cast iron grade 500 has been developed, and new studies searching for the replacement of the grade 450, with the aim of increasing the high-performance internal combustion engines life, as well as reducing their weight, are in development. Due to their operational characteristics, these engines are subjected simultaneously to thermal and mechanical cycles, which influence their useful life. Therefore, the characterization of the resistance to these types of loads for materials selection for these engines, is very important. Thus, the objective of this work was to study the thermomechanical fatigue life of two vermicular cast irons in conditions close to those to which internal combustion engines are subjected. The materials were characterized by chemical and metallographic analyses and tensile tests. The thermomechanical fatigue tests were carried out at temperatures ranging from 50 ºC to 420 ºC, and a dwell time of 180 seconds. The vermicular cast iron grade 500 exhibited higher tensile strength, with higher ductility when compared to the grade 450, as well as higher fatigue strength. These properties were related to the size and distribution of eutectic cells (graphite) in the matrix.

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Section: Discussionsupporting

confidence: 56%

Section: Resultsmentioning

confidence: 88%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Thermomechanical fatigue behavior of CGI 450 and CGI 500 cast irons

Ferreira¹,

Bon²,

Bose³

et al. 2022

Tecnol. Metal. Mater. Min.

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“…A new grade of CGI -GJV500 -has been introduced [11] by changing the graphite morphology. A remarkable result in terms of thermo-mechanical fatigue was described by Bon et al [12] for this new grade, which presented a 150% increase in fatigue life when compared to GJV450. The authors found that the graphite structure in the eutectic cell of GVJ500 changes from worm to round shape at the graphite boundaries, imposing more difficulties to propagate cracks.…”

Section: Introductionmentioning

confidence: 65%

The effect of graphite number per area on tribological behavior of high-strength compacted cast irons in lubricated tests

Pintaúde¹,

Wollmann²

2022

Tecnol. Metal. Mater. Min.

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“…Specifically those which exist in an oxidation environment in conjunction with cyclic changing temperature, for example, cast manifolds. [10][11][12][13] Thermomechanical fatigue (TMF) behaviors of high Si ductile iron were investigated under out-of-phase (OP), in-phase (IP), and constrained strain-control conditions with the test temperature window holding inside ranges between 300 and 800°C. 14 The four deformation/damage mechanisms were considered: (i) plasticity-induced fatigue, (ii) intergranular embrittlement, (iii) creep, and (iv) oxidation.…”

Section: Introductionmentioning

confidence: 99%

Improving High-Temperature Performance of High Si-Alloyed Ductile Iron by Altering Additions

et al. 2020

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High alloyed Si ferritic ductile irons can offer potential benefits because they combine high strength, ductility at room temperature, and low oxidation rate at high temperature. However, there is one known drawback and that is these cast irons have limited performance during thermal cycling due to a significant drop of ductility at warm temperatures. This decrease in ductility has been linked to poisoning ferrite grain boundaries by Mg. Therefore, thermodynamic simulations were used to identify altering additions which were able to meditate this negative effect by forming intermetallic phases with Mg. To verify thermodynamic predictions, three alloys were cast including a base and two high Si ductile irons with additions of P and Sb. High-temperature performance of these alloys was experimentally verified including tensile properties at warm temperatures (350-550°C), oxidation in air at temperatures (700-800°C), and thermal cycling between 300 and 800°C. SEM and TEM analyses confirmed that the studied additions reacted with Mg forming different compounds which could prevent poisoning ferrite grain boundaries and improve high-temperature performance of high Si ductile iron.

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Fracture Micromechanisms Evaluation of High-Strength Cast Irons Under Thermomechanical Fatigue Conditions

Cited by 9 publications

References 10 publications

Thermomechanical fatigue behavior of CGI 450 and CGI 500 cast irons

Thermomechanical fatigue behavior of CGI 450 and CGI 500 cast irons

The effect of graphite number per area on tribological behavior of high-strength compacted cast irons in lubricated tests

Improving High-Temperature Performance of High Si-Alloyed Ductile Iron by Altering Additions

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