Automotive Pistons Research Articles

A systematic approach for responsiveness assessment for product and material flow in reconfigurable manufacturing system (RMS)

A reconfigurable manufacturing system (RMS) quickly changes machine configurations to adapt to variations in demand related to volume of product and design. A decision of machine configuration change is taken after considering many factors, such as time, effort and cost. This research proposes a systematic approach for responsiveness assessment for product and material flow in reconfigurable manufacturing system (RMS) by considering product and process characteristics. The proposed system uses three important metrics, namely reconfiguration effort, reconfiguration time and non-productive reconfiguration cost. The usefulness of the developed system is demonstrated with the help of an industrial case study of three hypereutectic aluminium automotive pistons from the same part family. These pistons are made of FM-425 aluminium alloy that contains 16.5 percent of silicon. The system is suitable for comparing and selecting efficient machine configurations in a reconfigurable manufacturing system.

High-Temperature Mechanical Properties of Aluminum Alloy Matrix Composites Reinforced with Zr and Ni Trialumnides Synthesized by In Situ Reaction

High-temperature strengths and stabilities of Al3Ni and Al3Zr phases can be used to develop heat-resistant Al-matrix composites. In the current study, Al-1Mg-0.8Mn-0.8V alloy matrix composites are synthesized by in-situ reaction of K2ZrF6 salt and Ni powder to yield Al3Zr- and Al3Ni-reinforcing phases. The as-cast microstructural and room-temperature and high-temperature tensile properties of the composite are investigated. The microstructure of the composites contain α-Al, Al3Zr, Al3Ni, and Al10V phases. The eutectic mixture comprises alternating Al3Ni and α-Al phases with fine Al3Zr precipitates distributed in the interlamellar regions. The (2 pct Al3Zr + 15.2 pct Al3Ni)/Al-alloy composite shows the highest mechanical properties at room temperature, with a tensile strength of 198 MPa and a fracture strain of 6.55 pct. At 200 and 300 °C, tensile strengths of (2 pct Al3Zr + 13.3 pct Al3Ni)/Al-alloy and (2 pct Al3Zr + 15.2 pct Al3Ni)/Al-alloy composites reach 175 MPa and 166 MPa, and 191 MPa and 155 MPa, respectively. At 350 °C, the highest tensile strength of this composite family reaches 82 MPa, which surpasses some of the existing Al-Si alloys used in automotive pistons, suggesting its potential high-temperature applications. Analysis indicates that the fracture mode of the present composites is ductile. Transgranular cleavage fracture of coarse, brittle Al10V phase, and microvoid coalescence are the main failure mechanisms.

Realistic Image Synthesis of Imperfect Specimens using Generative Networks

This work explores conditional Generative Adversarial Networks (cGANs) as a tool to create realistic appearing CT slice images with pre-defined imperfections for the verification of automated defect detection algorithms. We aim to create an effective and efficient technique to simulate defects in CT slice images by implementing a new method which can simulate realistic textures and shapes. The problem is stated as an image to image translation task, where a new image is generated based on a given semantic description of the desired realistic image. This semantic description is a material based segmentation of the image with additional circular segments indicating the rough size and position of the intended defect. Based upon related work on cGANs, a convolutional neural network architecture is introduced and applied to our task. This method was trained and evaluated using 2D slice images derived from industrial CT datasets of automotive pistons. Our method showed promising results, producing convincing images in under one minute of computation with image resolutions of 256 by 256 pixels.

EN AW-4032 T6 Piston Alloy After High-Temperature Exposure: Residual Strength and Microstructural Features

This study aims to evaluate the effects of prolonged thermal exposure on both microstructural evolution and mechanical properties of the EN AW-4032 T6 piston alloy. For the purpose, the experimental activities have been carried out on samples machined from forged and heat-treated automotive pistons. The effects of overaging have been investigated in the temperature range of 140-290 °C, firstly by evaluating the time-temperature-hardness curves and then by carrying out room-temperature tensile tests on overaged samples. The material softening was substantial and extremely rapid when the soaking temperature exceeded 250 °C. During overaging, both the tensile strength and the residual hardness considerably decreased, and a relationship between these parameters has been established. The alloy behavior in the plastic field has been modeled according to the Hollomon’s equation, showing that both the strain hardening exponent and the strength coefficient are a function of the residual hardness. The results were finally related to the corresponding microstructural changes: OM and FEG-SEM metallographic and fractographic analyses on overaged samples gave evidence of coarsened precipitates along the grain boundaries.

Design and fabrication of functionally graded in-situ aluminium composites for automotive pistons

Engineering components with location specific properties are being designed and fabricated successfully using functionally graded materials (FGM). The present investigation aims at design, fabrication and evaluation of functionally graded automotive piston using in-situ primary silicon reinforced A390 aluminium composite by centrifugal casting technique with a view of obtaining improved thermo mechanical properties at specific locations. The dies are designed and fabricated so as to obtain the primary silicon rich region towards the head portion of the piston. FGM pistons with A390 and A390-0.5%Mg are produced. They are characterised along the vertical cross section of the piston from piston head towards the skirt by microstructural, chemical, mechanical, thermal and tribological characterisations methods. The results are also compared with that of gravity cast piston. Microstructure and chemical composition analysis of FGM piston shows graded distribution of primary silicon from the head portion of the piston towards skirt and a eutectic composition in the skirt region. That yields an increase in hardness towards the head region. The wear testing revealed that the gradation also resulted in a remarkable enhancement of the wear properties of the piston head.

Effects of Sr and pressure on microstructure, mechanical and wear properties of near eutectic Al–Si piston alloys

Near eutectic Al–Si alloys exhibit smaller coefficients of thermal expansion than those of hypoeutectic and hypereutectic alloys and are thus used preferentially to fabricate automotive pistons. The mechanical properties of near eutectic Al–Si alloys depend on the alloying elements used and the micro structural changes induced by the rate of cooling and the heat treatment to which they are subjected. In this study, Sr is added as a modifier in an Al–Si–Cu–Ni–Mg alloy and subjected the alloy to a pressure and a heat treatment in order to carry out a systematic inquiry to discover and examine the effects of Sr on and wear characteristics of the alloy. The addition of Sr, the application of a pressure, and the heat treatment produced a finer microstructure and resulted better properties. The fracture and wear mechanisms of alloy specimens subjected to tensile and wear tests were investigated using scanning electron microscopy.

Transient micromechanical deformation and thermomechanical fatigue damage in AlSi based piston alloys under superimposed high cycle mechanical and low cycle thermal loading*

Abstract Presently, AlSi based alloys, consisting up to 12 element systems, are used in the manufacture of automotive pistons for diesel engines. The pistons combustion wall is subject to complex superimposed transient mechanical and thermal loading with peak operating temperature representing a homologous temperature range Thom of 0.8 to 0.9. Using a special superimposed thermomechanical bench test apparatus, engine-like TMF loading has been reproduced and a number of semi in-situ experiments have been carried out to evaluate key microstructure damage mechanisms. The evolution of microstructural damage at the interface between hard Si inclusions and the softer Al matrix has been documented using scanning electron microscopy. The deformation characteristics at the Si/Al interface have been recreated using FEA techniques incorporating non-linear elasto-viscoplastic properties for the matrix material. Comparisons of bench test fatigue lives for transient superimposed high frequency and microstructural TMF loading for two different thermal cycles are then compared to isothermal mechanical load histories.

An Area-Average Correlation for Oil-Jet Cooling of Automotive Pistons

Laboratory tests were performed to measure cooling rates of an impinging oil-jet on the underside of an automotive piston as functions of oil nozzle-to-piston surface spacing, oil pressure, oil temperature, and piston temperature. Based on these results, area-average Nusselt number correlations were derived for a Reynolds number range of 100–4500, a Prandtl number range of 90–750, and a nozzle-to-piston surface spacing range over 73–160 mm, which are within the ranges expected for oil-jet cooling of automotive pistons.

Development of New High-Strength and Heat-Resistant Mg-Zn-Y-X (X=Zr and Ag) Casting Alloys

In order to develop a high strength and heat-resistant magnesium alloy, we focused on controlling microstructure of Mg96Zn2Y2 (at %) casting alloy by the addition of a 4th element. Initially, we investigated the effects of zirconium addition and cooling rate for grain refinement on microstructure and mechanical properties. Consequently, Mg95.8Zn2Y2Zr0.2 casting alloy contains fine equiaxed grains (approx. 0.01 mm), and it exhibits tensile and fatigue properties equivalent to or higher than those of commercial aluminum alloys at high temperature above 473 K. At 523 K, this alloy exhibited a tensile strength of 223 MPa nearly twice that of A4032-T6 alloy used in typical automotive pistons. The Mg95.8Zn2Y2Zr0.2 casting alloy also reveals sufficient ductility and good castability, characteristics not common in current heat-resistant magnesium alloys. Next, we focused on controlling microstructure of Mg96Zn2Y2 casting alloy by the addition of Ag. Mg96Zn2Y2 cast alloy is composed of alpha-Mg phase, long-period stacking ordered phase and Mg3Zn3Y2 phase; on the other hand, Mg-Zn-Y-Ag cast alloy had 4th phase by an addition of Ag. A substantial increase in yield strength at room temperature, without grain refining, was the result.

EFFECT OF SOLUTIONISING TIME ON MECHANICAL PROPERTIES OF SQUEEZE CASTED AL 6082 – SICP COMPOSITE

Aluminum matrix composites refer to the class of light weight high performance aluminum centric material systems. The unique tailorability of the composite materials for the specific requirements makes these materials more popular in a variety of applications such as aerospace, automotive (pistons, cylinders, liners, bearings), and structural components, resulting in savings of material and energy. In this project, fabrication of Aluminum MMC by liquid metallurgy route (Squeeze Casting) is discussed in detail. The mechanical properties of 6082 aluminum alloy discontinuously – reinforced with fine particulates of SiCp reinforcement and solutionising time during heat treatment of the composite on hardness, density and impact strength have been evaluated. The cardinal reasons behind the variation in the hardness and impact strength have been discussed.

Modification of Outer Layer of Al-Si Alloys by Doped Fe Atoms

The modification of the outer layer of Al-Si alloys doped with iron atoms was examined. The samples both were taken from automotive pistons and they also were prepared in the laboratory. In any case, they were used as basic raw materials for examination. It was found that the structure and properties of these alloys are very much dependent on the cooling rate, composition and heat treatment. The iron atoms are usually doped, in order to diminish and stabilize the thermal expansion coefficient of the alloys. However, this process makes the alloys to become harder and harder; thus leading the alloys to a degradation of their mechanical behavior at elevated temperatures. Optical Microscope observations, SEM analysis of the interactive surface layers and XRD measurements were performed on tested samples. At elevated temperatures a large homogenized zone extended to about 500 (μm) without an apparent distribution of the silicon dendrites or faceted crystals was formed. Moreover at the surface of the so called homogenized zone a layer of about 35 (μm) was formed inside of which iron atoms were migrated. This layer is mainly responsible for scuffing phenomena.

Fracture and Fatigue Behaviour of Aluminium Matrix Composite Automotive Pistons

The fracture and fatigue behaviour of prototype automotive pistons produced in an aluminium alloy matrix composite in industrial conditions has been studied. Fracture toughness increased when the testing temperature rose from 20° to 75°C and kept near constant up to 250°C, when a significantly lower value was recorded. A change in the failure operating mechanism, which can explain this trend, was observed by analysing the fracture surfaces in the scanning electron microscope. Room temperature fatigue tests performed with R = 0.1 stress ratio led to an average value of the Paris law exponent higher than those reported in aluminium alloys but low for an industrially produced brittle composite. A higher exponent and a much larger scattering were observed in those fatigue tests carried out under R = 0.5 stress ratio.

Investigation of mechanical properties of intermetallic phases in multi-component Al–Si alloys using hot-stage nanoindentation

Multi-component Al–Si alloys are important for the engineering applications such as automotive pistons. The presence of additional elements in the Al–Si alloy system allows many complex intermetallic phases to form. The mechanical properties of different intermetallic phases have been investigated as a function of temperature using hot-stage nanoindentation. In particular, the hardness and modulus of a number of phases have been established for a range of alloy compositions. In this study, the results show that both hardness and reduced modulus increase as the Ni ratio (Ni/(Ni + Cu)) of the AlCuNi phases increases (Al 3Ni 2 > Al 7Cu 4Ni > Al 2Cu) up to 350 °C. The creep effect of the intermetallic phases has also been investigated with a heating stage and indicated that the hardness strongly depends on the creep rate of the phase, particularly in the Al 2Cu phase. The Ni containing phases (Al 3Ni 2 and Al 7Cu 4Ni) have a good high temperature stability up to 200 °C; however, they drop significantly at 350 °C due to the fact that the frequent jumps of Cu and Ni atoms cause disordered structures. The Si and α-AlFeMnSi phases have good mechanical properties up to 350 °C corresponding to their good creep resistance. Al 5Cu 2Mg 8Si 6 with a lower hardness and elastic modulus exhibits the most stable phase at elevated temperatures, which is correlated with its good creep resistance.

Wear behaviour of an aluminium matrix composite

ABSTRACTThe wear behaviour of a composite material consisting in AS12UNG alloy reinforced with 15% short fibres of alumina has been studied. The material composition and the wear test conditions were defined in order to evaluate the potential performance of automotive pistons produced with such composite composition. As initially expected, the results indicate that an increase in the sliding velocity lead to higher wear rates in the stationary stages, and higher applied loads also induced acceleration in the wear process. Also, reciprocating sliding movement is clearly more damaging than the circular. However, results have shown that wear rates at 150 °C are lower than those recorded at room temperature representing a promising result for the use of this material in components that operate in this condition. This advantageous behaviour is lost at temperatures near to 300 °C, when a marked increase in the wear rate and a signification contribution of adhesive wear were observed.

Corrosion resistance and properties of pump pistons coated with hard materials

Low expansion aluminium–silicon eutectic alloys are cast to produce most of the automotive pistons. The structure and properties of these alloys are very much dependent on the cooling rate, composition, modification and heat treatment operations. In this study, locally available automotive ‘scrap pistons’ were used as basic raw materials and a natural gas fired crucible furnace was used for melting purpose. The wear behaviour of both as-cast and heat treated specimens were studied under dry sliding conditions at room temperature using a pin-on-disc type wear testing apparatus. The extent of wear damage and the type of wear were investigated by means of weight loss measurement and optical microscopy techniques. The full heat treatment showed a great influence on the wear properties of the aluminium–silicon piston alloy as it reduced the wear rate of the specimens. The exceptional high tensile strength and hardness were attributed to the heat treatment condition with decrease in ductility. Significant changes in structure were also observed to occur specially in the primary and eutectic silicon phases. Some of the results of this study can be recommended for tribological use of this alloy in manufacturing automobile spare parts.

Study on wear properties of aluminium–silicon piston alloy

Low expansion aluminium–silicon eutectic alloys are cast to produce most of the automotive pistons. The structure and properties of these alloys are very much dependent on the cooling rate, composition, modification and heat treatment operations. In this study, locally available automotive ‘scrap pistons’ were used as basic raw materials and a natural gas fired crucible furnace was used for melting purpose. The wear behaviour of both as-cast and heat treated specimens were studied under dry sliding conditions at room temperature using a pin-on-disc type wear testing apparatus. The extent of wear damage and the type of wear were investigated by means of weight loss measurement and optical microscopy techniques. The full heat treatment showed a great influence on the wear properties of the aluminium–silicon piston alloy as it reduced the wear rate of the specimens. The exceptional high tensile strength and hardness were attributed to the heat treatment condition with decrease in ductility. Significant changes in structure were also observed to occur specially in the primary and eutectic silicon phases. Some of the results of this study can be recommended for tribological use of this alloy in manufacturing automobile spare parts.

Ageing characteristics of aluminium alloy aluminosilicate discontinuous fibre reinforced composites

Development of continuous fiber reinforced metal matrix composites is aimed at providing high specific strength and stiffness needed for aerospace and some critical high temperature structural applications. Considerable efforts have been made, during the last decade, to improve the strength of age-hardening aluminium alloy matrix composites by suitable heat treatment. It has also been well established that age-hardenable aluminium alloy composites show accelerated ageing behavior because of enhanced dislocation density at the fiber/matrix interface resulting from thermal expansion mismatch between ceramic fiber and the metal matrix. The accelerated ageing of aluminium alloy composites either from dislocation density or the residual stress, as a result of thermal expansion mismatch is dependent on the size of whisker and particulate. Investigations have also been made on the effect of volume fraction of particulate on the ageing behavior of aluminium alloys. The present investigation is concerned with characterization of age-hardening behavior of an Al-Si-Cu-Mg(AA 336) alloy alumino-silicate discontinuous fiber-reinforced composites (referred to as aluminium MMCs in the present text) being developed for automotive pistons. An effort is made to study the effect of volume fraction of the reinforcement on age-hardening behavior of this composite.

Effect of process variables on structure and properties of aluminium–silicon piston alloy

The majority of automotive pistons are cast in one of the groups of low expansion Al–Si eutectic alloys. The structure and mechanical properties of these alloys are highly dependent upon cooling rate, composition, modification and the heat-treatment operations. The effect of these variables were investigated in this study, using locally available automotive `scrap pistons' as basic raw materials. Strontium master alloy was used as the source of the modifier and a natural-gas-fired crucible furnace was used for melting purposes. The microstructures of the alloy, both in the modified and unmodified conditions, were studied in this investigation. Properties such as the ultimate tensile strength (UTS), percentage elongation, hardness and percentage porosity for both rates of cooling have been determined, both with and without the addition of strontium. Significant changes in structures were observed to occur, especially in the primary and eutectic silicon phases. Full heat treatment has also shown a great influence on the structure and properties of the aluminium–silicon piston alloy. The residual stress in the modified alloy is fully relieved due to thermal treatment. Finally, attempts were made to correlate the observed structures and properties obtained during the experiment.

UNS A02220

Abstract UNS No. A02220 is an age-hardenable aluminum casting alloy. It is hard and wear resistant and has good strength at elevated temperatures. It has good foundry characteristics in many respects and is produced as sand and permanent-mold castings. Among its applications are bushings, automotive cylinder heads and pistons. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and compressive and shear strength as well as fatigue. It also includes information on high temperature performance and corrosion resistance as well as casting, heat treating, machining, and joining. Filing Code: Al-272. Producer or source: Various aluminum companies.

ALUMINUM 336.0

Abstract ALUMINUM 336.0 is a high-silicon aluminum-base alloy recommended for high-strength permanent-mold castings. It responds to an age-hardening heat treatment. Its applications include automotive and diesel pistons, pulleys and sheaves. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and compressive and shear strength as well as creep and fatigue. It also includes information on high temperature performance and corrosion resistance as well as casting, heat treating, machining, and joining. Filing Code: Al-266. Producer or source: Various aluminum companies.