Effects of cellular growth on fatigue life of directionally solidified hypoeutectic Al-Fe Alloys

Abstract

Al-Fe hypoeutectic alloys are a family of casting alloys characterized by cell growth, low cost and appreciable formability. It is well known that fatigue strength is a requirement of prime importance considering the nature of load typically observed during operations involving the risers used in oil extraction. The aim of this study is to examine the influence of cell size and its intercellular phase distribution on the fatigue life (N f ) of the directionally solidified Al-0.5, 1.0 and 1.5wt% Fe alloys. A water-cooled vertical upward unidirectional solidification system was used to provide the castings. Microscopy light and SEM microscopy were used. It was found that fatigue life decreases as cell spacing (λ c ) increases. Smaller cell spacing allows a homogeneous distribution of Al-Fe fibers to happen within the intercellular regions, which tends to improve the mentioned fatigue property. ); where A and B are constants] seems to be able to encompass the fatigue life variation along the Al-Fe alloys.

Rapid Cellular Crystal Growth of TiAl-Based Intermetallic without Peritectic Reaction by Melt-Quenching in Ga–In Liquid

“…Resulting from the change of heat transfer mechanisms, the tip cooling rate and growth velocity dramatically decreased with the increase of growth distance, whereas the temperature gradient in the mushy zone had a little change (∼1.6 × 10 7 K/m) during the rapid cellular growth. According to the above-mentioned research results from Garcia et al, − ,, λ 1 is the power function of Ṫ with −0.55 exponent under unsteady heat flow conditions, namely, in which A is a constant mainly determined by the solidification characteristic of alloy.…”

“…At first, researchers experimentally studied the cellular growth behavior by in situ observation of transparent dilute organic alloys. , In recent years, extensive research about cellular growth has been mostly performed in dilute alloys as a consequence of the velocity range for cellular growth being enlarged with decreasing concentration . Xu et al , have researched the cellular growth of Zn-rich Zn–Ag alloys by rapid solidification methods in detail; Ma et al − have studied the cellular growth behavior of Zn-rich Zn–Cu alloys by Bridgman solidification, and some other relative research studies also have been completed in dilute eutectic Al–Fe, − Al–Mg–Si, and peritectic Al–Ti alloy systems . The above research studies mainly concentrated on determining the relationship between the microstructural parameter (cellular spacing λ 1 ) and solidification parameters (temperature gradient G , growth velocity V , and cooling rate Ṫ ); it has been shown that the microstructural parameter decreases as the solidification processing parameters increase, for constant concentration.…”

“…However, these expressions were found not to be applied to cellular growth under unsteady-state conditions yet. Garcia et al − ,, have systematically researched cellular growth behavior of various alloy systems during transient directional solidification, and all of the research indicated that λ 1 is the power function of Ṫ with −0.55 exponent under unsteady heat flow conditions, which is very valuable to the further research about unsteady-state cellular growth of alloys. Considering the dilute alloys lack application prospects, then it is more meaningful to deeply research the cellular growth behavior of engineering alloys, and the relative research results on dilute alloys have laid significantly the theoretical and experimental foundation for further research.…”

Microstructural Patterns, Microsegregation, Porosity, and Mechanical Properties of Hypoeutectic Al-Fe Alloy, and its Dependency with Solidification Thermal Parameters

“…Researches involving unidirectional solidification under transient heat flow for pure metals and their alloys have come into attention [4][5][6][7][8][9][10][11][12][13][14][15] . This technique allows the investigation of the solid/liquid surface morphology, microstructure and microsegregation as a function of the thermal parameters, which is very attractive for investigating the influence of these parameters in solidification of metals and alloys.…”

“…The experimental results showed that the microhardness can be correlated with Fe content of the alloy and cellular spacing. Ribeiro et al 5 examined the solidification of Al-Fe alloys in the upward unidirectional solidification system. The focus of that study was to examine the influence of cell size and its intercellular phase distribution on the fatigue life.…”