The anti-corrosive stainless environment in both onshore and offshore applications is principal for many countries around the world. Hence, using duplex stainless steel (DSS) more and more is obvious.
Duplex stainless steel grades have added a vital role in formulating some lined-up structures and new machinery successfully over the past few decades. It has also seen as the advantageous areas for the stainless steel industry for the automotive sector.
Duplex Stainless Steel
Stainless steel is defined as “duplex” when it consists of a two-phase microstructure: combining austenitic and ferritic grains. They provide outstanding and greater corrosion resistance than the common austenitic stainless steels, combined with very high mechanical properties.
They are also more resistant to stress-corrosion cracking (SCC) than austenitic stainless steels.
Duplex stainless steel is a very alluring constructional material for use in intrusive surroundings. This is because of its several benefits over austenitic stainless steels. Duplex stainless steel has attractive pitting and crevice corrosion resistance, which are vastly resistant to chloride stress-corrosion cracking and are about twice as strong and secure as standard austenitic steels.
It has already become clear that stainless steel has applied in many areas for its mechanical properties such as very high strength and yield.
Usage of Duplex Stainless Steel
These features are significantly applicable to the automotive sector, where they can lead to significant weight savings and, at the same time, to safety improvements. There has been a significant increase in the use of duplex stainless steel in the automotive industry. Both as for components of cars, busses, trucks, and trailers, as well as for the processing plants for the automotive industry.
However, duplex steel sections are used in various branches such as:
- chemical processing, transport and storage
- oil and gas exploration and offshore rigs
- pulp and paper manufacturing
- oil and gas refining
- marine environments
- pollution control equipment
In the context of automotive production plants, duplex stainless steel finds use especially in painting lines. There corrosion becomes the major issue, but conveyor lines made with duplex steel sections ensure excellent corrosion resistance.
Particular Properties of Duplex Stainless Steel
Due to the high level of chromium and nitrogen content, and also molybdenum, duplex stainless steel offers significant resistance to localized and uniform corrosion. It also offers a quite good weldability (with some precautions) because it can be welded with both TIG and MIG, as well as laser hybrid.
Stainless steel is easily prone to stress-corrosion cracking in chloride containing environment at elevated temperatures. Duplex stainless steel on the other hand is less susceptible to this type of corrosion.
Both have been tested at laboratories, and the results show that duplex stainless steel withstands stress-corrosion cracking under many conditions. Conventional austenitic stainless steel grades on the contrary are expected to fail.
Duplex stainless steel tolerates twice as high values than conventional austenitic or ferritic stainless steels, as far as tensile strength is concerned. This makes duplex stainless steel an ideal material for designing taking advantage of the possibilities given by reducing weight.
Automotive and transport sectors are taking advantage of using duplex stainless steel to reduce weight. Thus they are reducing material and life cycle costs, in example for accelerating and decelerating unnecessary mass.
Duplex steel sections have lower nickel and molybdenum constituents than their austenitic counterparts with identical corrosion resistance. This on the other hand results in lower material cost.
One of the most superior aspects of duplex stainless steel is the resistance to chloride stress-corrosion cracking (CLSCC). So it provides an extensive range of corrosion resistance in several surroundings.
Duplex stainless steel has significantly better toughness than ferritic grades. However, they do not reach the excellent values of austenitic grades.
Duplex stainless steel is available principally as plate material, hot rolled flat bars, pipes and flanges, very little hot rolled sections. Structural sections like beams, angle bars, sections, and channels are available exclusively as welded profiles. Montanstahl focusses its production on duplex steel sections. So we laser-hybrid weld all grades of the different categories: lean duplex, duplex and super duplex.