More of an economic choice if high concentrations of chloride aren’t present.Type 304 (EN steel number 1.4301) and type 316 (EN steel number 1.4401, 1.4436) have very similar physical and mechanical properties but their major difference remains in their resistance to corrosion in different environments: Other mechanical or physical properties may also need to be considered to meet service performance.
When selecting a specific grade of stainless steel for a given application, the first and foremost criteria is the corrosion resistance.
304 stainless steel series#
The 300 series which include Type 304 and Type 316 are the most widely used stainless steel. This family has two sub-groups of 200 and 300 series. Austenitic stainless steel is achieved by alloying nickel, which gives it excellent formability and weldability. Stainless steels are classified by their crystalline structure, with the most widely produced family being Austenitic. Therefore, there are numerous stainless steel grades with varying content of chromium and other elements to suit different environments and applications. are added to stainless steel to enhance its properties such as formability, strength and chemical resistance. In short, the corroding agent (an example being CI-) gets into the crevice interfering with the alloy’s ability to re-form a passivating film, and causing oxidation.īesides chromium, other alloying elements such as molybdenum (Mo), nickel (Ni), titanium (Ti), etc. This mode of corrosion happens in contact areas between parts, under gaskets or seals or spaces filled with deposits. Crevice corrosion is in principle similar to pitting corrosion and occurs in confined spaces (crevices) where access to the environment is limited, as seen in Figure 4.Figure 2 shows how the chromium layer (dark black) protects the rest of the alloy from oxidation, even when damaged. The stable film formed on the stainless steel is self-repairing in case it is scratched or temporarily disturbed by an upset environment. This process, which results in resistance to corrosion, is called passivation. In stainless steel, the chromium oxide creates a very thin stable surface film, which protects the metal from corrosion by limiting the oxygen’s access to the rest of the metal. Stainless steels are 100% recyclable.Ĭhromium (Cr) is a hard metal which reacts with oxygen when exposed to water or air. These alloys are produced primarily for resistance to corrosion or oxidation, which happens when metals reacts with oxygen (in water or air) and rust. What is Stainless Steel?Īll steels have the basic iron and carbon composition, but the term stainless steel refers to a wide range of steel alloys with a minimum of 10.5% chromium content by mass. Understand what can cause corrosion in your application and speak with a Tameson Engineer to ensure you select the appropriate material for each application. However, type 304 is still commonly used as it offers good protection to most applications and is the more economical choice. In short, stainless steel 316 offers better protection than type 304 to 99% of common media present in applications.
0 kommentar(er)
