In the automotive industry, the demanding of the more efficient vehicle had being discovered important by the consumer. Energy consumption and air pollution must have to be reduced directly to make sure that vehicles are the green element for people. All of the characteristic of Aluminium such, good corrosion resistance, light-weight application and the recycling potential can be the good element to replace other element such copper or steel that are lack of the advantages than aluminium alloy. In this paper concluded the advantages using the aluminium alloy rather than used the other material in the automotive industrial field.
INTRODUCTION
The first advantage of the aluminium alloy that we will discuss is about good corrosion resistance. There are three sites in Japan that have been conducted the field exposure tests of aluminium alloys. The meteorological data showed that the dew point of the ambient atmosphere and aluminium panels remained constant for the short-term. Constant dew point corrosion tests were employed to reproduce atmospheric corrosion of aluminium alloys in the laboratory. We did tests in 7 days in the laboratory that are similar to those formed after 3 months of exposure at coastal sites to measured the corrosion rates, corrosion morphology and corrosion product composition. Not only did the constant dew point corrosion test effectively reproduce the atmospheric corrosion of aluminium alloys, it also accelerated it.
For the second advantage is the light-weight application. Light-weight components are the important interest for all branches that produce moving masses. The aim to reduce weight has to be accompanied by high production efficiency and component performance. In this paper we will discuss about general consideration on light-weight structure. By what factor we must considered to change the structure in light-weight form and the effect using this method that we will discuss in this side.
Besides, problem of air pollution must have to be reduced in the production of thing in automotive side. In this paper we discuss a new method of recycling aluminium and aluminium-alloy chips coming from the machining of semi-finished products, which are very difficult to recycle by conventional methods, is presented. The method consists in the conversion of the chips directly without melting processes into a semi-finished product. We using a powder metallurgy technique followed by extrusion. This method has been applied to the production of composite materials, characterised by good properties. The new method is environmentally friendly and gives saving in material, labour and energy.
OBJECTIVES
In this research, the objectives to be achieved are as follow:
1. To investigate the effect of the good corrosion resistance of Aluminium alloy to the automotive industry.
2. To investigate the effect of the light-weight application of Aluminium alloy to the automotive industry.
3. To investigate the effect of the recycling potential of Aluminium alloy to the automotive industry.
LITERATURE REVIEW
Competition of material in the automotive market has been traditionally intensive. Since 1920s steel has been the dominant material used in building automobiles. There always be a question to the types of materials are likely to be winners in the 21st century. The automotive manufacturers' decisions on material's usage are complex and are determined by a number of factors. The increasing requirement to improve fuel economy triggered by concerns about global warming and energy usage has a significant influence on the choice of materials.
recycling potential
Aluminium usage in automotive applications has grown more than 80% in the past 5 years. A total of about 110 kg of aluminium:vehicle in 1996 is predicted to rise to 250 or 340 kg, with or without taking body panel or structure applications into account, by 2015. There are strong predictions for aluminium applications in hoods, trunk lids and doors hanging on a steel frame. Fig. 2 shows the development of aluminium consumption for automotive application in Europe. As shown in Fig. 2, a significant increase in sheet aluminium for automotive applications is expected, which will be discussed later with more details. Recent examples of aluminium applications in vehicles cover power trains, chassis, body structure and air conditioning.
As indicated in Fig. 2, aluminium castings find the most widespread use in automobile. In automotive power train, aluminium castings have been used for almost 100% of pistons, about 75% of cylinder heads, 85% of intake manifolds and transmission (other parts-rear axle, differential housings and drive shafts etc.) For chassis applications, aluminium castings are used for about 40% of wheels, and for brackets, brake components, suspension (control arms, supports), steering components (air bag supports,steering shafts, knuckles, housings, wheels) and instrument panels. The spreading of usage of aluminium alloy all over the world are been affected by 3 factors that are:
Good corrosion resistance
We use the 5xxx and 6xxx series aluminium alloys that are commonly used in marine applications because of it characteristic that are low in density, good mechanical properties and better resistance to corrosion. For the corrosion resistance, it is related to the formation of an oxide (passive) film, that appear on the alloy surface under normal atmospheric conditions. It was formed in non-uniform, thin and non-coherent. Therefore, it gives a certain level of protection under normal conditions. The conventional laboratory scale tests have been desisn to evaluate the atmospheric corrosion resistance of materials. We use the salt spray test (ASTM B117) as an acceleration test to test that type of alloy. ASTM G85-A5 and SAE J2334 as the cyclic corrosion tests, and constant relative humidity tests have also been used to analyze the actual atmospheric corrosion at a laboratory level.
By measuring fluctuations in the night and day temperature and relative humidity, it found that the dew point of outdoor air remains approximately constant and that humidity depends on the air temperature. (Muto and Sugimoto, 2010)
For this project a testing method based on it has thus been proposed to simulate the actual environment of atmospheric corrosion on stainless steel. The testing method, called the constant dew point corrosion test, employs a diurnal cycle of temperature and humidity at a constant dew point temperature. This testing has been demonstrated that this method reproduces atmospheric corrosion well in the laboratory not only in the case of stainless steel but also for other alloys.
The aim of this study was to examine whether the constant dew point corrosion test can appropriately reproduce the atmospheric corrosion of aluminium alloys and with that we know that aluminium alloy is a good corrosive resistance. In this work, we analyze the corrosion rates, corrosion morphology and corrosion product composition of aluminium and its alloys after field exposure tests and compared with those after the constant dew point corrosion tests.
Light-weight application
The main factors for the application of new technologies are the costs. We focusing for light-weight alloys which have be as substitution of metals by beneath all technological properties, the economical aspects have to be considered. By knowing the costs for a certain structure with an existing material for different transport systems it is possible for to estimate the cost savings that we assume as S over the lifetime for the reduced fuel consumption due to the lower weight. For a typical car this value S is approximately 9.4 Euro/kg, for an aeroplane 120 Euro/kg and for a rocket 8000 Euro/kg.
The costs Cconv. for typical structures in conventional design can be derived from the literature. For cars these costs are in the range between 14 Euro/kg for steel components and 55 Euro/kg for Al- structures. Typical costs for aeroplanes are between 42 Euro/kg (steel) and 155 Euro/kg (aluminium), whereas rockets reach "astronomic" prices between 6.000 and 100.000 Euro/kg .
Using the equation:
S = the cost savings over the lifetime due to reduced fuel consumption for light-weight structures
R= weight ratio between conventional and new structure with material substitution.
Depending on the prefer type of loading the structure has to withstand, typical R-values and therefore, typical allowable costs for economic material substitutions can be derived, we see Table 1. This clearly shows that even estimating with a very similar equation a priori considerations of allowable costs are possible and show good agreements with literature values.
As we can see an allowable costs Csubst. for cars are in the range 29 Euro/kg (substitute steel by aluminium) and 23 Euro/kg (substitute steel by titanium). The economic window for automotive production can be very small, but using modern mass production techniques material substitution may be economically reasonable. The very high values for aircraft and rocket structures give evidence that nearly every effort for weight reduction is economically worthwhile. The estimated costs are the total costs for the new structure with material substitution consisting mainly of tooling, manufacturing and material costs.
The distribution of the costs for typical structures from steel, aluminium, titanium and magnesium is shown in Fig. 1. Therefore, knowing the total allowable costs for a new structure the maximum manufacturing costs can be estimated to be 25% of the total costs easily from Fig. 1. By determining, e.g. the costs for the laser joining process it is possible to decide whether a laser based substitution structure can be economically manufactured.
Recycling potential
A technology that has been developed systematically in recent years is that of manufacturing sintered products with pre-determined properties. It has been demonstrated that such products can be manufactured from waste materials.
When metal products are manufactured, considerable amounts of waste in the form of chips and discards are produced. These waste and scraps are returned to smelters, whereby some of the metal is recovered and reutilized in production processes. During the recycling of the waste a lot of the metal is lost as a result of oxidation, and the costs of labour and energy as well as the expenditure on environmental protection raise the general cost of such processes. Nevertheless, recycling of aluminium scrap requires only approximately 5% of the energy needed to produce it from ore. Therefore, secondary aluminium has found great acceptance, world-wide. Amongst the different types of aluminium scrap, chips from the machining of semi-finished products are most difficult to recycle by conventional methods.
This is due to their elongated spiral shape and small size in comparison with other forms of scrap . The apparent density of the chips is low, which makes them inconvenient for handling and transportation and their surface area is relatively large and covered with oxides and machining oil, which is not good for their recycling.
The conventional recycling process (CRP) of chips is carried out with a melting phase as a fundamental step.
In the case of chips, their surface area to volume ratio is very high. The oxide film on the chips is dependent on the total surface area and, together with new oxide skin formed during the melting phase, have a noticeable influence on metal losses. The skim formed during melting can contain upto 95% metal, a further processes being needed to recover the metal from it.
Therefore, to facilitate handling and to reduce the loss of metal during remelting, it is necessary to increase the bulk density of the scrap to the value of about 1 kg/dm3. Even under such conditions, it is estimated that an average metal loss of about 20% occurs during the remelting stage operation and, moreover, the conventional recycling process is characterised by high energy consumption, high operating costs and a large number of operations in Fig. 1. Additional new scrap is generated after melting due to casting, cutting and rolling or extrusion processes. The scraps produced during post-melting processing results in 25 wt.% of metal losses .
This means that the conventional process can recycle less than 55% of aluminium scrap. This problem is very significant, because the amount of recycled aluminium has been growing systematically since the sixties and its consumption at present is very high.
Aluminium scrap melting creates potential hazards. Moisture and the contamination of chips may results in molten metal explosion, injuries, damage to bag-houses, ductwork, equipment.
Finally, the CRP of chips is characterised by environmental pollution, mainly due to fumes and drosses generated during the melting stage of the chips, high energy consumption and low recovery efficiency due to melt loss and post-melting scraps processing.
In recent years increasing interest has been shown in chip recycling processes other than melting. Some proposals concern pulverised chips, further processed by sintering and hot working. Other approach methods and have made use of comminuted chips, having a size of 1-4 mm. Such chips are much more coarse than those used in conventional powder processes.
Because of the different processing of various types of scrap it becomes necessary to make use of the best economics method of recycling. This kind of recycling can be applied not only to aluminium and its alloys, but also to iron, copper and its alloys and, to some extent, to cast iron.
The importance of recycling can be illustrated by the benefits resulting from the management of aluminium and aluminium-alloy chips. In 1993, about 50,000 tonnes of aluminium was produced in Poland and the waste in the form of chips alone was about 2500 tonnes. Considering that aluminium recovery in the case of the conventional (metallurgical) method amounts to about 54% of the scrap (this value is much lower for chips) and to about 95% for the direct conversion method, it becomes possible to recover the remainder 40% (at least) of the metal from the chips.
This means the recovery of additional approximately 1000 tonnes of aluminium per year in Poland. It should be noticed that in the industrialised countries of the West, the consumption of re-used metals shows a growing tendency. In the case of aluminium, it has risen from 35 to 55% in recent years, whilst in Poland it has dropped from 23 to 15%.
To sum up, it should be emphasised that the environmentally clean direct conversion of aluminium scrap into compact metal results in 40% material, 26-31% energy and 16-60% labour savings.
The aim of this paper is to present the results of the direct conversion of granulated aluminium and its alloys chips into finished products. Due to the high ratio of the surface aluminium-oxide layer area to the volume of the chips, the material after processing has the structure of a composite. This is a factor having a positive effect on the mechanical properties of extruded bars. An investigation of the effect of a small addition of strengthening particles other than crumbled surface aluminium oxide layer into granulated aluminium chips on the properties of extruded final products are also presented.
CONCLUSION
Aluminium alloy is the material that are really demanding in the automotive nowadays. In order to examine whether the constant dew point corrosion test can appropriately reproduce the atmospheric corrosion of aluminium alloys, corrosion tests were performed on AA1100, AA6061 and 4 N Al under the cyclic wet-dry conditions at the constant dew point of 28 °C and with the chloride deposition of 1 g m−2, which simulated marine atmospheric environments in the summer season in Japan. It was found that the corrosion mass loss increased as the number of cycles increased in accordance with a power-law formula. The corrosion pattern after the 7-cycle test was pitting, and the corrosion products consisted of basic aluminium sulphate, basic aluminium chloride, aluminium hydroxide, and basic aluminium carbonate. The corrosion rates, corrosion morphology, and corrosion product composition were similar to those observed on the samples exposed for a few months in Miyakojima, a typical coastal site. The constantdewpoint corrosion test, therefore was shown capable not only of reproducing the atmospheric corrosion of aluminium, but also of accelerating it.
Besides, A new generalised concept for evaluating material substitution for light-weight constructions in transport applications has been developed. An easy equation allows a- priori considerations to determine whether a material substitution under given loading conditions is economically reasonable.Stating from this point typical examples for new laser-based structures were presented. For aeroplane manufacturing the weldable alloy AA 6013 will substitute a conventional riveting structure. The described example gives details about the process stabilisation that enables the practical use of laser beam welding for this high-quality welds.
The weight loss tests revealed that all of the alloys exhibited low corrosion rate values, indicating the beneficial use of these alloys in marine environments.
Pit morphology on potentiodynamically polarized samples showed hemispherical isolated pits on the 5083 alloys. The 1100 samples, however, revealed higher numbers of shallow pits.
The results obtained in this study indicate that the type of intermetallic particles in aluminum alloys plays a major role in passivity breakdown and pit morphology of aluminum alloys in seawater.
It can be recycled by the direct comersial method, which is characterised by low energy-consumption and large material savings. The most suitable way of recycling the chips is their processing through hot extrusion. This method is relatively simple and it limits itself to the comminution, cold press molding and hot extrusion of the chips. The method can be used to extrude products in the form of bars, sections and pipes, which can be formed further as if they were made of a homogenous and plastic material. By employing hot extrusion, sintering can be eliminated, since the latter proceeds with suf®cient intensity during extrusion.
