Stainless Steel Cracking

Cracks initiated at intergranular corrosion penetrations propagating by corrosion assisted fatigue.

Stainless steel cracking. Chloride stress corrosion cracking in austenitic stainless steel is characterized by the multi branched lightning bolt transgranular crack pattern. Not only can duplex stainless steel hold up reliably through trauma impact but through corrosion as well. The temperature thresholds are well above the 212 f 100 c range indicating that exposures to atmospheric boiling in neutral chloride solutions are very unlikely to produce cracking. Stress corrosion cracking scc is the growth of crack formation in a corrosive environment.

How to reduce the risk of stress corrosion cracking scc the risk of stress corrosion cracking scc can be minimized through plant and equipment design. 3 different types of stainless steel include the elements carbon from 0 03 to greater than 1 00 nitrogen aluminium silicon sulfur titanium nickel copper selenium niobium. The micrograph below x300 illustrates scc in a 316 stainless steel chemical processing piping system. The typical crack morphology for chloride stress corrosion cracking consists of branched transgranular cracks.

276 is a group of iron based alloys that contain a minimum of approximately 11 chromium. To understand the corrosion resistance properties of duplex stainless steel you must also understand the concept of stress corrosion cracking. Fatigue cracking of a 316l stainless steel nozzle sleeve from a chemical processing vessel. It can lead to unexpected and sudden failure of normally ductile metal alloys subjected to a tensile stress especially at elevated temperature scc is highly chemically specific in that certain alloys are likely to undergo scc only when exposed to a small number of chemical environments.

Scc in a 316 stainless steel chemical processing piping system. Forensic failure analysis corrosion investigation metallurgical testing and engineering located in mooresville nc. 1 cause of cracking. What might be a simple mistake on carbon steel could make for a costly lesson on stainless steel so it s important to know what you re doing before you get started.

The martensite phase is brittle and easy to crack. Figure 1 shows the cracking that occurred on a 6mo super austenitic stainless steel n08367 exposed to 0 2 chlorides at 500 f 260 c. 3 a composition that prevents the iron from rusting as well as providing heat resistant properties. Analysis of common problems in stainless steel deep drawing process.

Austenitic stainless steel is a meta stable type which will undergo transformation during deformation thus induce martensitic phase. Austenitic stainless steel has a high cold hardening index 0 34 for ss. Stainless steel isn t as cost effective a material as carbon steel. Hydrogen cracking is also a big concern when welding stainless steel.