The combination of tensile stress and a specific corrosive environment can crack stainless steels. Apr 14, 2015 this safety alert highlights the issue of chloride stress corrosion cracking of stainless steel lokring pipe connectors and advises dutyholders on actions required. A 316l stainless steel bellows failure was investigated. Stress corrosion cracking facts and how to reduce the.
This mode of attack is termed stress corrosion cracking scc. Alloy 904l performs better than other austenitic stainless steels due to the higher alloying of nickel and molybdenum. Chloride stress corrosion cracking and 316 stainless steel. The objective of this work was to evaluate the atmospheric chloride stress corrosion cracking susceptibility of austenitic type 304, 304l, and 316l stainless steels. Stress corrosion cracking facts and how to reduce the risk. Chlorideinduced stress corrosion cracking of 316 stainless. Environmental factors in the stress corrosion cracking of type 316l stainless steel and alloy 825 in chloride solutions g. Stress corrosion cracking scc is cracking due to a process involving conjoint corrosion and straining of a metal due to residual or applied stresses. This together with slightly higher stacking fault energy schramm and reed 1975 are the main reasons for better resistance of type 316 316l stainless steel than type 304304l to stress corrosion cracking in sodium chloride solutions. Localized corrosion and stress corrosion cracking of stainless steels. Therefore, the scc concerns for spent fuel storage canisters identified in a november 2004 presentation by nuclear and.
Stress corrosion cracking and hydrogen embrittlement of type. The use of this stainless steel grade in chloride containing environments is not normally. With its highly alloyed chemistry 25% nickel and 4. Controlling chloride induced stress corrosion cracking of aisi 316l. Some 95% of 316l chemical plant equipment failures may be attributed to chloride scc. Scc in a 316 stainless steel chemical processing piping system.
Alloy 904l is a superaustenitic stainless steel that is designed for moderate to high corrosion resistance in a wide range of process environments. There is a synergistic relationship between dissolved oxygen and the chloride level. It can be detrimental to austenitic stainless steels, one of the main reasons these steels are not considered a cureall for corrosion problems. Only the 25% nickel grades have similar cscc resistance. Figure 2 shows the cracking threshold for 304l and 316l stainless steel as a. Austenitic stainless steels chloride induced stress. Susceptible alloys include 304l, 316l, 321, and 347. Although the type 316 alloy is somewhat more resistant to scc than the 18 cr8 ni alloys because of the molybdenum content, they still are quite susceptible. May 27, 2011 for austenitic stainless steels chlorides are the major cause of stresscorrosion cracking scc. This behaviour is explained on the basis of the passivation and pitting characteristics of 316l steel in chloride solution. Cragnolino 1 center for nuclear waste regulatory analyses, southwest research institute, 6220 culebra road, san antonio, tx, 782385166. Effects of marine environments on stress corrosion cracking.
A precursor of stress corrosion cracking in chloridebearing environments is pitting. It is difficult to control the temperature, while changing pipe material or eliminating residual stresses associated with welding and forming the pipework is costly and. The higher nickel and molybdenum content in this grade allows it to demonstrate better overall corrosion resistant properties than 304, especially with regard to pitting and crevice corrosion in chloride environments. This safety alert highlights the issue of chloride stress corrosion cracking which has been found to affect stainless steel grade 316316l lokring pipe connectors. Duplex stainless steels, austenitic stainless steels with a high nickel content. The use of a duplex stainless steel with molybdenum such as stainless alloys 2205 or 2507 would resist crevice corrosion and stress corrosion cracking. The incubation time for stress corrosion cracking can be very short, sometimes measured in hours. Therefore, pitting, crevice corrosion, and stress corrosion cracking scc of. Outperforms alloys 304l and 316l in stress corrosion cracking resistance in chloride containing aqueous solutions its corrosion rate in boiling nitric acid 65% is higher than that of alloy 316l its high yield strength allows duplex 2304 to perform well in abrasioncorrosion applications.
Feb 18, 2004 grade 316 is the standard molybdenumbearing grade, second in importance to 304 amongst the austenitic stainless steels. Simulated sea salt was deposited on the surface of the samples, using a salt fog procedure. This safety alert highlights the issue of chloride stress corrosion cracking which has been found to affect stainless steel grade 316 316l lokring pipe connectors. The most common type of stress corrosion cracking in stainless steels occurs in chloride environments, which will be the focus of. Effect of chloride deposition on stress corrosion cracking of 316l stainless steel used for intermediate level radioactive waste containers. Stress corrosion cracking scc results from the combined action of three factors. The objective of this work is to evaluate if atmospheric stress corrosion cracking can develop in stainless steel cask. Effect of chloride deposition on stress corrosion cracking of 316l. In all cases of failure by stress corrosion cracking, the following three factors must be present. Chloride stress corrosion cracking in austenitic stainless steel. Although no stainless steel grade is totally immune. This paper presents the effect of buffing on the stress corrosion cracking scc resistance of machined surfaces of aisi 316l stainless steel ss.
Pdf atmosphericinduced stress corrosion cracking of austenitic. Austenitic stainless steels chloride induced stress corrosion cracking cscc chumpes petroleum 16 mar 18 10. Stainless steel 316 and 316l grade 316 is the standard molybdenumbearing grade, second inoverall volume production to 304 amongst the austenitic stainless steels. The environmental factors that increase the cracking susceptibility include higher temperatures, increased chloride content, lower ph, and higher levels of tensile stress. Chloride stress corrosion cracking clscc is one of the most common reasons why austenitic stainless steel pipework and vessels deteriorate in the chemical processing and petrochemical industries. The failure was by chloride stress corrosion cracking scc. Chloride stress corrosion is a type of intergranular corrosion and occurs in austenitic stainless steel under tensile stress in the presence of oxygen, chloride ions, and high temperature. The chloride induced 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. As 316 but with lower carbon content to minimise carbide precipitation during welding.
The occurrence of atmosphericinduced chloride stress corrosion cracking in types 304l and 316l stainless steels contacted with seasalt and magnesium chloride deposits has been studied under controlled conditions of relative humidity ca. 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. Although no stainless steel grade is totally immune to chloride scc, the relative. Environmental factors in the stress corrosion cracking of.
There are several types of stress corrosion cracking scc, for example, chlorideinduced scc and h 2sinduced scc. Stress corrosion cracking of an austenitic stainless steel in. Outperforms alloys 304l and 316l in stress corrosion cracking resistance in chloride containing aqueous solutions its corrosion rate in boiling nitric acid 65% is higher than that of alloy 316l its high yield strength allows duplex 2304 to perform well in abrasion corrosion applications. Chloride stress corrosion cracking clscc is a type of stress corrosion cracking scc and is one of the most well known forms of scc in the refining and chemical processing industries. This article describes the susceptibility of 316l stainless steel to stress corrosion cracking scc in a nitritecontaining chloride. To that end, types 304, 304l, and 316l stainless steel ubend samples were fabricated and placed in an environmental chamber. For example, chloride stress corrosion cracking of austenitic stainless steel has been experienced in hotwater jacketed pipes carrying molten chocolate in the food industry. For austenitic stainless steels chlorides are the major cause of stresscorrosion cracking scc. Stress corrosion cracking of the aisi 316l stainless steel. Chlorideinduced stress corrosion cracking of powder. Type 304 stainless steel an overview sciencedirect topics. It also has a high resistance to pitting in chloride solutions, a high resistance to both crevice and stress corrosion cracking.
Although the alloys 316 and 317l are somewhat more resistant to scc than the 18 cr8 ni alloys because of their molybdenum content, they still are quire susceptible. However, there is limited use with hydrochloric acids. Stress corrosion cracking of the aisi 316l stainless steel haz in a pwr nuclear reactor environment. Chloride stress corrosion cracking in austenitic stainless steel is characterized by the multibranched lightning bolt transgranular crack pattern. Scc is often associated with chlorides, but can also occur with caustics and other corrosive media. Stress corrosion cracking of an austenitic stainless steel. Addition of nitrite to the chloride solution, which is reported to have inhibitive. A precursor of stress corrosion cracking in chloride bearing environments is pitting corrosion, occurring if the stainless steel is not sufficiently resistant to pitting. This safety alert highlights the issue of chloride stress corrosion cracking of stainless steel lokring pipe connectors and advises dutyholders on actions required. Deterioration by clscc can lead to failures that have the potential to release stored energy andor hazardous substances. The most common environmental exposure condition responsible for scc of stainless steels is the presence of chlorides.
It is thought to start with chromium carbide deposits along grain boundaries that leave the metal open to corrosion. Stress corrosion cracking scc is a common issue with many specialty alloys. However, molybdenum itself does not get incorporated in the passive film. Alloy 316316l is molybdenumbearing austenitic stainless steel. This paper described the mechanism of chloride induced stress corrosion cracking of oil tube as a result of improper material selection and lack of maintenance. External chloride stress corrosion cracking of stainless. In this case, in particular, in a chloride containing environment, stress corrosion cracking is a potential degradation mechanism of canister failure due to formation of salt deposits and the deliquescence process epri, 2005. Chloride stress corrosion cracking and 316 stainless steel moltenmetal chemical 20 jul 11 07. This article describes the susceptibility of 316l stainless steel to stress corrosion cracking scc in a nitritecontaining chloride solution. 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. For type 316 austenitic stainless steel, a slope of 91 mv was reported for cl. A corrosive medium especially chloridebearing or hydrogensulphide h 2s media. Article pdf available in materials performance 194. This paper described the mechanism of chlorideinduced stress corrosion cracking of oil tube as a result of.
The molybdenum gives 316 better overall corrosion resistant properties than grade 304, particularly higher resistance to pitting and crevice corrosion in chloride environments. Addition of nitrite to the chloride solution, which is reported to have inhibitive influence on corrosion of stainless. Pdf the occurrence of atmosphericinduced chloride stress corrosion cracking in types 304l and 316l stainless steels contacted with seasalt and. When stainless steels are fully immersed, it is rare to see chloride stress corrosion cracking at temperatures below 60 c 150 f. The susceptibility was also found to increase with nitrite concentration. Chloride stress corrosion cracking in austenitic stainless.
An example is hot potable water under heat transfer conditions which permit chlorides to concentrate locally. Alloy 316 316l is molybdenumbearing austenitic 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. Failure analysis of corrosion on stainless steel fasteners. 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. This diagram figure 1 is analogous to a similar diagram for caustic. Stress corrosion cracking in 316l stainless steel bellows of a. Chloride stress corrosion cracking inspectioneering.
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