Stress corrosion cracking in duplex stainless steel

The combination of tensile stress and a specific corrosive environment can crack stainless steels. Request pdf stress corrosion cracking of duplex stainless steels the relative superiority of duplex stainless steels dss over austenitic grades. Deterioration by clscc can lead to failures that have the potential to release stored energy andor hazardous substances. Duplex stainless steel is a practical solution to most 304l or 316l scc failures. Stress corrision cracking is a relatively rare form of corrosion, which requires a specific combination of tensile stress, temperature and corrosive species, often the chloride ion, for it to occur. Datasheet for sandvik 3re60 duplex stainless steel. Sandvik 3re60 was the first modern duplex stainless steel with nitrogen added for improved welding properties. Hydrogeninduced stress cracking of swaged super duplex. Scc will occur when stainless steels are subjected to tensile stress, while in contact with solutions containing chlorides. Feb 28, 2018 duplex stainless steel has become more popular for its combination of strength and affordability. It is the most widely used duplex stainless steel grade and is characterized by high yield strength, double that of the standard austenitic stainless steel grades.

The ferritic and austenitic stainless steel grades have approximately equal proportions i. Although no stainless steel grade is totally immune. Because of the increasing use of duplex stainless steels in the offshore oil production, a question has invoked whether the crevice corrosion impairs the sulfide stress cracking ssc resistance of the super duplex stainless steels. Stress corrosion cracking of ldx 2101 duplex stainless steel. It can lead to unexpected sudden failure of normally ductile metal alloys subjected to a tensile stress, especially at elevated temperature. Penn stainless inventory now includes duplex 2507, which is a super duplex stainless steel with 25% chromium, 4% molybdenum, and 7% nickel. Stainless steels are damaged by stress corrosion cracking in conditions containing chlorides at the high temperatures. Abstract duplex stainless steel is widely used in the oil and gas industry due to its inherent resistance to localised corrosion and stress corrosion cracking. Various techniques are utilized to grade the steel types considering their resistance to scc and the.

This mode of attack is termed stress corrosion cracking scc. Stress corrosion cracking of a duplex stainless steel. Most notably, pitting and cracking in this instance had initiated andor. These more resistant materials are expected to crack when exposed to practice g36 as ubends. Their mixed microstructure provides improved resistance to chloride stress corrosion cracking in comparison to austenitic stainless steel types 304 and 316. Hydrogen induced cracking of subsea duplex stainless steel twi. Lippold j and alexandrov b, phase transformations during welding and postweld heat treatment of a 12cr6. Stress corrosion cracking scc of duplex stainless steel. The most common type of stress corrosion cracking in stainless steels occurs in chloride environments, which will be the focus of this discussion. They are being offered by all the major stainless steel mills for a number of reasons.

To understand the corrosion resistance properties of duplex stainless steel, you must also understand the concept of stress corrosion cracking. Abstract a recent subsea failure of two subsea connectors made of uns s32760, a 25 wt% cr super duplex stainless steel, led to an extensive root cause failure analysis. Oct 21, 2019 chloride stress corrosion cracking is a localized corrosion mechanism like pitting and crevice corrosion. Increasing nickel content above 18 to 20% or the use of duplex, or ferritic stainless steels improves resistance to cscc. The micrograph on the left x300 illustrates scc in a 316 stainless steel chemical processing piping system. Greater corrosion resistance particularly stress corrosion cracking. Earlier duplex alloys have had moderate resistance to general corrosion and chloride stress corrosion cracking, but suffered a substantial loss of properties when used in the aswelded condition. Lets discuss the concept of stress corrosion cracking and what it entails, and how it relates to duplex.

There is a conference on the subject of duplex every 23 years where dozens of highly technical papers are presented. Corrosion resistance stress corrosion cracking 2205 is a cost effective solution for many applications where 300 series stainless steels are susceptible to chloride stress corrosion cracking scc. Pre stands for pitting resistance equivalent and is defined as, in weight%. This alloy is designed for applications which require exceptional strength and corrosion resistance. May 27, 2011 duplex stainless steel is a practical solution to most 304l or 316l scc failures. Stress corrosion cracking of new 2001 leanduplex stainless. The nitrogen serves to significantly improve the corrosion resistance of the alloy. Duplex stainless steel and corrosion cracking its when austenitic stainless steel and ferritic stainless steel are put together that they become truly resistant to stress corrosion cracking. Cscc can attack highly resistant austenitic stainless steel. Chlorideinduced stress corrosion cracking of powder. Austenitic stainless steel may be susceptible to chloride stress corrosion cracking cscc. High residual or applied stress, temperature above 6571c 150160f and chlorides increase the. Corrosion of stainless steel by hot caustic research using solutions of chemically pure caustic sodium hydroxide naoh led to the development of a diagram that attempts to delineate the param eters of concentration and tem perature governing stress corrosion cracking scc of type. Stress corrosion cracking scc is the growth of crack formation in a corrosive environment.

Stress corrosion cracking in duplex stainless steel. Assessment of susceptibility to chloride stress corrosion. This family of alloys has achieved widespread industrial application, including in the offshore oil and gas sector, due in part to an attractive. The steel has excellent resistance to chloride stress. Stress corrosion cracking facts and how to reduce the risk. C for 500 h under drops of synthetic seawater det, drop evaporation test. The material is used frequently in, for example, refineries with stress corrosion cracking scc problems. Stress corrosion cracking of an austenitic stainless steel in. The most commonly available duplex in north america is 2205, at a cost roughly 20% above that of 316l. Recommended practice dnvrpf112, design of duplex stainless steel subsea equipment exposed to cathodic protection, 2008. Only the 25% nickel grades have similar cscc resistance. 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. Investigation of stress corrosion cracking of austenitic. Corrosion and stress corroson cracking scc susceptibility of duplex stainless steels dss depend on alloy composition, microstructure and temperature.

It requires a susceptible material and, depending on the material, sufficient levels of. Formability formability of ak steel 2205 duplex is better than that of ferritic grades, especially in heavy sections, but not quite as good as the austenitic stainless steels. Hydrogen induced cracking of subsea duplex stainless steel. However, duplex stainless steel can still be susceptible to stress corrosion cracking in h2scontaining environments, if the environmental conditions are aggressive enough. Chloride stress corrosion cracking of a super duplex. Stress corrosion cracking facts and how to reduce the. Duplex stainless steel sandvik materials technology.

The chlorideinduced stress corrosion cracking scc resistance of nitrogenalloyed, powder metallurgically pm produced and hot isostatically pressed hip duplex stainless steels dss was investigated and compared to the scc resistance of two commercial wrought forged dss. Pitting corrosion has been reported from household bleach spills on stainless steel 304 type sinks in domestic environments. Stress corrosion cracking of new 2001 leanduplex stainless steel reinforcements in chloride contained concrete pore solution. Stress corrosion cracking of duplex stainless steel scc stress corrosion cracking is a form of corrosion which occurs with a particular combination of factors. A recent subsea failure of two subsea connectors made of uns s32760, a 25 wt% cr super duplex stainless steel, led to an extensive root cause failure analysis. The standard 304304l and 316316l grades are most susceptible. Duplex stainless steel has become more and more popular for its combination of strength and affordability. Introduction to 22% chrome duplex stainless steel lff group. Duplex stainless steel is widely used in the oil and gas industry due to its inherent resistance to localised corrosion and stress corrosion cracking. Scc is highly chemically specific in that certain alloys are likely to undergo scc only when exposed to a small number of chemical environments. Normally 50 deg c but can occur at lower temperatures around 25 deg c in specific environments, notably swimming pools. The significance of these failures has led to research to define critical loading conditions for hisc, to allow confident design of components in future.

Astm g123 002015 standard test method for evaluating. A precursor of stress corrosion cracking in chloridebearing environments is pitting corrosion, occurring if the stainless steel is not sufficiently resistant to pitting. Stress corrosion cracking of duplex stainless steels. Weldability ak steel 2205 duplex can be readily welded with gas tungsten arc. Chloride stress corrosion cracking the greatest corrosion advantage for duplex stainless steels is their improved resistance to cscc when compared to the austenitic grades. Chloride stress corrosion cracking in austenitic stainless steel.

Intergranular stress corrosion cracking of welded steel twi. Caustic may crack carbon as well as stainless steel. Turnbull, threshold temperature for stress corrosion cracking of duplex stainless steel under evaporative seawater conditions, corrosion. Other forms of scc in stainless steels include caustic cracking and polythionic acid scc.

An electrochemical study author links open overlay panel e. Corrosion of stainless steel by hot caustic research using solutions of chemically pure caustic sodium hydroxide naoh led to the development of a diagram that attempts to delineate the param eters of concentration and tem perature governing. Crevice corrosion induced ssc of 25cr tungsten alloyed. The susceptibility of 22 cr and 25 cr duplex stainless steels to stress corrosion cracking under evaporative seawater conditions has been evaluated using a modified drop evaporation test. Chloride stress corrosion cracking is a localized corrosion mechanism like pitting and crevice corrosion. The word duplex refers to the twophase microstructure of ferritic and austenitic steel grains. Chloride stress corrosion cracking of a super duplex stainless steel. It also demonstrates good fatigue strength, as well as outstanding resistance to stress corrosion cracking, crevice, pitting, erosion, and general corrosion in severe environments. There is an additional risk of stress corrosion cracking scc at higher temperatures. It is primarily because of its resistance to chloride stress corrosion cracking that 22% cr duplex stainless steel has replaced type 316316l stainless steel for many process piping applications.

Threshold temperature for stress corrosion cracking of duplex. Not only can duplex stainless steel hold up reliably through trauma impact, but through corrosion as well. The most common environmental exposure condition responsible for scc of stainless steels is the presence of chlorides. Chloride stress corrosion cracking in austenitic stainless. The higher alloyed duplex stainless steel alloys, ones with significant molybdenum and nitrogen additions, can be superior to 316 ss in. A small number of duplex and superduplex stainless steel components have failed in subsea service due to hydrogen induced stress cracking hisc.

Hydrogeninduced stress cracking of swaged super duplex stainless steel subsea components, corrosion 757. Scc is often associated with chlorides, but can also occur with caustics and other corrosive media. Request pdf stress corrosion cracking of duplex stainless steels the relative superiority of duplex stainless steels dss over austenitic grades with regards to stress corrosion cracking scc. Stress corrosion cracking of ldx 2101 duplex stainless steel in chloride solutions in the presence of thiosulphate author links open overlay panel f. Hydrogeninduced stress cracking of swaged super duplex stainless steel subsea components, corrosion. This can be seen in the pren pitting resistance equivalent number of duplex stainless steel as well as in its tensile strength. Typical applications for duplex alloys are heat exchangers, tubes, pipes, pressure vessels and tanks in the oil and gas and chemical processing industries. Woollin p, postweld heat treatment to avoid intergranular stress corrosion cracking of supermartensitic stainless steels, proc conf stainless steel world 2005, kci publishing, paper no. Drop evaporation test method, author steinsmo, u and drugli, j m, abstractnote stress corrosion cracking scc of chloride exposed stainless steels under evaporative conditions has for long been recognized as a factor that needed special. Supermartensitic stainless steels smss, including both lean grades without molybdenum and high grades with 2% molybdenum, have shown sensitivity to intergranular corrosion or stress corrosion cracking igscc in weld hazs during laboratory testing in chloride solutions acidified with co 2 at above about 100c. Pdf threshold temperature for stress corrosion cracking.

Duplex stainless steel offers high mechanical strength and excellent corrosion resistance properties. Type 2205 duplex stainless steel is a grade that offers very good pitting and uniform corrosion resistance, high strength and high resistance to stress corrosion cracking. Chloride stress corrosion cracking in austenitic stainless steel is characterized by the multibranched lightning bolt transgranular crack. Stress corrosion cracking of ductile niresist irons and. There is a lot of marketing activity surrounding these grades. Woollin p and gregori a, avoiding hydrogen embrittlement stress cracking of ferritic austenitic stainless steels under cathodic protection, proc conf omae 2004, paper 51203. Scc can occur typically in hot water tanks or swimming pools. Threshold temperature for stress corrosion cracking of. Stress corrosion cracking of an austenitic stainless steel. Stress corrosion cracking in duplex stainless steel great. Stress corrosion cracking of ldx 2101 duplex stainless.

Traditional austenitic steels are found to be more susceptible to such attack however duplex grades are less prone to it. Chloride stress corrosion cracking clscc is one the most common reasons why austenitic stainless steel pipework and vessels deteriorate in the chemical processing and petrochemical industries. Stresscorrosion cracking resistance is superior to the austenitic grades of stainless steel. Methods of minimizing chloride stress corrosion cracking. Pitting or crevice corrosion can occur on most stainless steel grades. Duplex grades are usually divided into three subgroups based on their corrosion resistance. Stress corrosion cracking of a duplex stainless steel onepetro. In this study the effect of sulfide containing caustic environment and material properties dss composition and microstructure on the corrosion and scc of dss in pulping liquors synthetic white liquor was evaluated. Stress corrosion cracking scc stainless steel test specimens were simultaneously subjected to mechanical stress and exposed to 8%wt. Stress corrosion cracking scc is a common issue with many specialty alloys. Stress corrosion cracking scc of uns s31603 austenitic stainless steel ass, uns s32205 duplex stainless steel dss and uns s32750 super duplex stainless steel sdss was investigated. The duplex stainless steels were developed to exhibit comparable general corrosion resistance as 316ss, but with reduced susceptibility to chloride stress corrosion cracking.