Stainless steel is thoroughly used in real-life applications in which to prevent corrosion. The material is also expected to have a tough, scratch-
resistance surface in many end-uses. Surface engineering proposes solutions when improved wear resistance is required Alenka Kosmac, 2013.
2.2 TYPE OF STAINLESS STEEL
There are five families of stainless steels and their percentage of usage of each type are as shown in the Table 2.1.
Table 2.1 : Percentage Usage Of Each Type Of Stainless Steels Source : www.worldstainless.org, retrieved October, 23 2014.
Percentage Usage Of Each Type Of Stainless Steels.
• Austenitic Stainless Steel – 200 series and 300 series 72
• Ferritic Stainless Steel – 400 series 24
• Martensitic Stainless Steel 2
• Precipitation Hardening 1
• Duplex Stainless Steel 0.6
2.2.1 Ferritic Stainless Steel
These steels have a similar microstructure to carbon and low carbon steels and are based on Chromium with small amounts of Carbon usually less than
0.10 BSSA Guide, 2013. With an amount between 10.5 - 27 of chromium and a very small amount of Nickel, Ferritic Stainless Steel serves have better
engineering properties than austenitic grades but have a lower resistant to corrosion. Due to lack toughness in welds and cannot be hardened by heat treatment, they are
usually limited in usage to relatively thin sections. In a condition where there is
present of sea water, high Chromium steels with addition of Molybdenum can be used. Besides that they are magnetic and less expensive. Ferritic steel is less ductile
than austenitic steel Sand Meyer Steels, retrieved October 29, 2014
2.2.2 Austenitic Stainless Steel
Stainless steels have an austenite crystalline structure, which is a face- centered cubic crystal structure. To retain an austenitic structure at all temperature,
they contain a maximum of 0.15 carbon, a minimum of 16 chromium and sufficient content of nickel andor manganese. They cannot be hardened by heat
treatment but have the useful property of being able to be hardened to high strength level whilst retaining a useful level of ductility and toughness. By lowering the
nickel content and increasing the content manganese will result in weak corrosion resistance Internal Stainless Steel Forum, 2005.
The austenitic stainless steel is usually more expensive than the ferritic grades. However, they have good formibility and weldability which is
generally much better than the ferritic grades. They also excel in the aspect of toughness, even to very low cryogenic temperature and they are not magnetic BSSA
Guide, 2013. Table 2.2 shows the major alloy element composition of austenitic stainless steels.
Table 2.2 : Major Alloy Element Composition Of Austenitic Stainless Steels. Source : Gedge et. al. 2008
Steel Designation Alloy Composition Min from EN 10088
EN 10088 ASTM
International Chromium
Nickel Molybdenum
1.4301 304
17 8
- 1.4404
316 L 16.5
10 2
1.4435 316 L
17 12.5
2.5
2.2.3 Martensitic Stainless Steel
