There will always be a need for formability tests. The effect of composition and processing modifications on formability must be determined during alloy development, preferably without resorting to expensive field forming trials in the initial stages.
Tests are often needed in the analysis of field forming problems requiring the comparison of problem lots to a data base. Tests are also needed for quality assurance, especially since it appears that many sheet users are working toward the use of test results as acceptance criteria.
For many steel grades microalloying with niobium is the key to achieve their characteristic property profile.
Microalloyed HSLA steels were among the first high strength steel grades used in vehicle construction. In some recent passenger cars they account for up to 40% of the body mass.
The early grades were alloys of chromium, nickel and molybdenum. Thermodynamically, because the austenite is forming from the ferrite, it is impossible for the alloy to go past the equilibrium level of austenite.
Lean Duplex Stainless Steels have many end uses in oil and gas due to their high strength and good corrosion properties. They have been used for subsea applications including flexible flowlines, umbilical tubing, subsea manifolds, water injection lines and downhole chemical injection tubing.
Microalloy (MA) or High Strength Low Alloy (HSLA) steels constitute an important category of steels estimated to be around 12% of total world steel production.
HSLA steel typically contains 0.07 to 0.12% carbon, up to 2% manganese and small additions of niobium, vanadium and titanium (usually max. 0.1%) in various combinations.
The semi-solid processing of alloys is a relatively new commercial process which moved from a laboratory curiosity to a fully-fledged and viable manufacturing route in the 1970’s.
Lying between established solid and liquid state techniques, SSP allows the associated costs of solid state processing to be controlled and provides all the advantages of superior mechanical properties due to the precise changes in microstructure resulting from the slurry production steps.
Austenitic steels may undergo microstructural changes during short- or long-term exposure to high temperature. In the case of longer ageing times, other precipitates such as intermetallic phases are formed, which are usually accompanied by dissolution of carbides.
The intermetallic precipitations are of great interest not only because they exert influence on the mechanical properties but also because of their strong effect on the corrosive properties.