What is a superplastic material?

Superplasticity is the ability of a polycrystalline material to exhibit, in a generally isotropic manner, very high tensile elongations prior to failure (T > 0.5 Tm). The first observations of this phenomenon were made as early as 1912. Since then, superplasticity has been extensively studied in metals.

What is the requirement for superplastic forming?

3.1 Superplastic forming. Superplastic forming (SPF) involves slowly forming a sheet of material in a single sided tool or die using gas pressure at a temperature of about 500°C. A typical forming cycle for SPF is approximately 30 minutes or longer.

What is superplastic forming what is the major limitation of the superplastic forming of sheet metal?

The largest disadvantage of the process is its slow forming rate. Cycle times vary from two minutes to two hours, therefore it is usually used in low volume production applications. Another disadvantage is the non-uniformity of the produced part thickness.

Is superplastic an alloy of Aluminium?

Abstract: 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.

What is strain rate material?

Strain rate is the change in strain (deformation) of a material with respect to time. The strain rate at some point within the material measures the rate at which the distances of adjacent parcels of the material change with time in the neighborhood of that point.

What is plastically deformed?

Plastic deformation is the permanent distortion that occurs when a material is subjected to tensile, compressive, bending, or torsion stresses that exceed its yield strength and cause it to elongate, compress, buckle, bend, or twist.

What is bulge forming?

Bulge Forming is a process that involves expanding fluid in a rubber bladder, or bung, within a cavity die tool containing a sheet metal blank (cone or tube) to create a pre-determined shape reflected by the inner contour of the cavity die tool.

What is explosive forming?

An explosive forming is one of the techniques to form a metal plate using high shock pressure from the explosion. An explosive releases its energy instantly so that an extremely high pressure with short duration occurs at the instance of explosion. Because of this effect, the metal plate may stop its deformation.

What is superplastic behavior?

In materials science, superplasticity is a state in which solid crystalline material is deformed well beyond its usual breaking point, usually over about 600% during tensile deformation. Such a state is usually achieved at high homologous temperature.

What is strain rate sensitivity?

Strain-rate sensitivity (SRS) of flow stress is an important parameter for deformation mechanism of materials. Definition of SRS is based on incremental changes in strain rate during tests performed at a fixed temperature and fixed microstructure, to determine corresponding changes in flow stress.

What is the effect of temperature on ductility of super plastic alloys?

The further increase in temperature reduces the ductility because of the presence of excessive liquid phase at grain boundaries. Only 98% of elongation was obtained at the temperature of 600 °C.

What is strain rate in metal forming?

Abstract : In metal forming processes, the behavior of the metals undergoing large plast~c deformation is atyected by the dynamic or strain rate effects of the material and inertia effect. When the strain rate effect is significant, the forming pressure is lowered by decreasing the strain rate.