Last year the BSSA selected fifty grades of stainless steel. The fifty grades were picked out of roughly two hundred candidates and were then showcased, one grade per week, as a way of illustrating the properties of each grade of stainless steel on a regular basis. Let’s have a quick look at some of the grades on their list.
#4 – 2205 duplex
Number four on the list is 2205 duplex (1.4462), a generic term for the most common of the duplex stainless steels. This grade is typically applied in, for example, the offshore oil and gas business, desalination plants and the food processing industry. This grade of duplex is also often used in architecture and construction. Although the demand for duplex grades is led by the offshore oil and gas business, more and more applications of duplex can be found in other fields as well. Architectural works of art for example, like the Helix Bridge in Singapore. The reason that duplex is becoming more popular? Because it is truly a steel for all seasons!
#9 – 6% Mo
Number nine on the list of the BSSA is again a generic term: ‘6% Mo’ includes several highly alloyed austenitic grades. These grades have been especially developed to be able to deal with the harsh environment of chemical processing as well as highly aggressive seawater. Other fields of application for these austenitic stainless steel grades include metal refining, condenser tubing and aggressive food processing (soy sauce for example).
#34 – 304Cu
304Cu, thirty-four on the list, is based on the widely used 304 grade, with a significant addition of copper to reduce the work hardening of this grade of stainless steel. The approximate composition of 304Cu is 18 % Cr, 9% Ni, 3,5% Cu and 0,03% C. In addition to reduced work hardening, some other specific characteristics of this grade include easier machining than the 304 grades and resistance to becoming magnetic during cold working. 304Cu is for example applied in the automotive industry, chemical processing and the food and drink processing industry.
#50 – calcium treated grades
Next to the advantages that stainless steel holds, there is one important disadvantage compared to carbon and alloy steels, this is the difficulty with machining; however, there is a solution. To improve the machinability of many of the stainless steel grades, calcium is added. This leads – depending on the grade and component – to an improvement of 10–50% in productivity. Calcium treated grades can be found in all sectors where machined components are used. This has no significant effect on the corrosion resistance of the stainless steel.
The complete series of fifty grades of stainless steel can of course be found on the website of the British Stainless Steel Association.