It is known that superplasticity refers to the ability of a material to demonstrate under tensile tests very high uniform deformation more than several hundreds percents without visible necking. There are two basic requirements in order to achieve superplastic flow in a polycrystalline material. First, the material must have a very small and stable grain size less than 10 μm. Second, superplasticity is achieved only at relatively high temperatures above 0.5Tm (where Tm is the absolute melting temperature) because superplasticity is diffusion-controlled process. Continue reading
Aluminum is well established at the front of the pack with regards to providing the technological answer to the increasing challenges of light weighting whilst maintaining integrity of the material for the desired applications.
Semi solid rheocasting is a development within the casting sector which enables improved quality in die casting without increasing cost. Continue reading
The drive for lighter stronger materials in the automotive industry has driven the development and following popularity of aluminum alloys which possess some very specific property characteristics.
AlMgSi alloys are one such material group and they are particularly popular for their excellent castability, intrinsic hardness and good corrosion resistance.
There are numerous configurations of rolling mills including single stand mills and tandem stand mills.
One specific problem common to both configurations is related to the coating of the rolls which in turn can lead to surface quality issues on the finished strip. Countermeasures for this include the installation of brush rolls to maintain the cleanliness of the rollers.
The selection of aluminum for a specific use is normally in reaction to an ever increasing demand for an improved strength to weight ratio along with a number of other key property advantages.
Rolled aluminum can be presented in several forms including sheets, plates and foils, and is used in many industries adding to the flexibility and its position as a critical material for modern applications.
Superplastically formed (SPF) aluminum alloys have the ability to be stretched to several times their original size without failure when heated to between 470-520°C.
These dilute alloys containing zirconium, later to be known by the trade name SUPRAL, were heavily cold worked to sheet and dynamically recrystallized to a fine stable grain size, typically 4-5μm, during the initial stages of hot deformation.
In recent times there has been an ever increasing need for lightweight materials with increased strength to help meet tighter deadlines relating to cost savings.
Al-Mg alloys can offer excellent solutions for these requirements by exhibiting favorable formability, high strength and high strain hardening ability offering not only strong finished product but stable.
AlMg alloys have a wide range of advantageous characteristics which means they can be used in many different applications, with many being in extreme temperatures or other aggressive environments.
A prime example of such materials can be seen in the 5xxx series of alloys which display excellent corrosion resistance in combination with very good mechanical properties to cope in the harshest conditions such as marine environments.
Corrosion is the chemical reaction of a metal, in this case aluminum, with its environment, which leads to the deterioration of the properties of metals, aluminum in this case. Aluminum is a very reactive metal, but it is also a passive metal. This contradictory nature is explainable because nascent aluminum reacts with oxygen or water and forms a coherent surface oxide which impedes further reaction of aluminum with the environment.
Deep drawing is one of the most intensively studied process areas due to its close relationship with the automotive industry with focus not only on visual appeal but also paramount safety concerns.
However the most important benefit of using aluminum materials in the forming of automotive body parts is the high weight loss factor associated with these materials.