The key difference is the addition of molybdenum, an alloy which drastically enhances corrosion resistance, especially for more saline or chlorideexposed environments. Multipurpose stainless steel, originally used as a fluid flow tube in the oil and gas industry, is now more used in the chemical processing and petrochemical industries and as a digester in the pulp and paper industry. A film of more acidic corrodent solution is raised to ph 1. In contrast, type 304 stainless steel becomes resistant to cracking when prestrained above 20%. Pdf chloride induced stress corrosion cracking of type 304. The other main reason for stress relieving is to provide dimensional or shape stability. Alloy c276 nickel alloy plate has excellent corrosion resistance in both oxidizing and reducing environments. Molybdenum is a chemical element used for the strengthening and hardening of steel. Scc of the 300 series stainless steels is classically transgranular. Like 316, it is an austenitic stainless steel, meaning it is a metallic, iron allotrope. Below 80 degc they can be considered resistant to any concentration of sodium hydroxide, up to the limit of solubility. Selection of stainless steels for handling sodium hydroxide.
The micrograph on the left x300 illustrates scc in a 316 stainless steel chemical processing piping system. What is the maximum chloride in ppm that can be allowed in. Therefore, standard grades such as 304304l and 316316l are very. What is the difference between 304 and 316 stainless. Chloride induced stress corrosion cracking in standard austenitic stainless steels, viz. The molybdenum gives 316 better overall corrosion resistant properties than grade 304, particularly higher resistance to pitting and crevice corrosion in chloride environments. Comparative study of the effect of temperature on the corrosion behavior of 2205 duplex stainless steel and 316 austenitic stainless. What is temperature it is more important than concentration of chloride and anything higher than room temperature higher is worse. It occurs in austenitic stainless steel under tensile stress in the presence of oxygen, chloride ions and high temperature. Stress corrosion cracking of aisi 304 and aisi 316. The micrograph below x300 illustrates scc in a 316 stainless steel chemical processing piping system. Scc in a 316 stainless steel chemical processing piping system. After analyzing chemical composition makeup, corrosion resistance, cost and suitable applications, the key difference between 304 and 316 stainless steel is that 316 grade has better corrosion resistance thanks to addtion of molybdenum than 304, especially for chloride applications, and last longer service life. In case of duplex and stainless steel 316, there is no clear winner.
Again, 316ss is more resilient as it is less susceptible to corrosion from chlorine solutions than 304ss, which shows signs of corrosion at 2 ppm of chlorine and 316ss showing signs of corrosion at 4 ppm of chlorine. The aisi american iron and steel institute was the originator of the 300 and 400 series numbering system i. However, it can be susceptible to pitting and crevice corrosion in chloride environments. Rapid stress corrosion cracking of 304 stainless steel in mgcl 2fecl 3 solutions at 125 c has been shown to occur only when the ph of the corrodent liquid within the crack lay between 1. The scc susceptibility of sensitized type 304 stainless steel was studied using slow strain rate tests in 0. Furthermore, different surface treatments polished vs ground were also used. The stress corrosion cracking scc of aisi 304 and aisi 316 austenitic stainless steels in 0. Stainless steels types 304 and 316 can be considered resistant below 80 degc, up to the limit of solubility.
H 2 s can cause corrosion of stainless steels such as 316 and 410 stainless in the form of sulfide stress cracking. Chloride induced stress corrosion cracking of type 304 and. Stress relieving heat treatments for austenitic stainless. A particular problem for the common austenitic grades e. It contains high nickel content that is typically between 8 and 10. Occasionally, conditions are encountered that cause localized attack, usually. Duplex stainless steels have high resistance to localized corrosion particularly pitting, crevice corrosion, and stress corrosion cracking. It can lead to unexpected sudden failure of normally ductile metal alloys subjected to a tensile stress, especially at elevated temperature. Next to water, chloride is the most common chemical found in nature.
As american aisi basic grades, the only practical difference between 304 or 316 and 304l or 316l is carbon content. Influence of high temperature on corrosion behavior of 304. Type 316 ss is more corrosion resistant than 304 ss because of its higher nickel content and the addition of molybdenum 23% as an alloying element. Table 7 details more specific environments in which vari. What is the difference between 304 and 316 stainless steel. Chlorides are probably the single biggest enemy of stainless steel. The overall combination of increased nickel, molybdenum and other minor alloying tweaks improves the resistance of 316 ss to stress corrosion cracking, creeping, chemicals, solvents, sulfuric acids, and extreme temperatures. Stress corrosion cracking british stainless steel association. Sulfide stress cracking an overview sciencedirect topics. It is used in metal degreasing and cleaning processes in a wide range of industry applications. Influence of high temperature on corrosion behavior of 304 stainless steel in chloride solutions. Scc is often associated with chlorides, but can also occur with caustics and other corrosive media. While the surveyed studies all explore scc of austenitic stainless steels. Difference between duplex stainless steel s31803 s32205.
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. Chloride stress corrosion cracking cscc is a type of intergranular corrosion. Chloride stress corrosion cracking in austenitic stainless steel is characterized by the multibranched lightning bolt transgranular crack pattern. The combination of tensile stress and a specific corrosive environment can crack stainless steels. Austenitic steels of type astm 304 and 316 austenitic steels have limited. Comparision grade 304 304l 316 316l corrosion resistance. Stress corrosion cracking of sensitized type 304 stainless.
The methodology of the drip procedure of the standard test method for evaluating the influence of thermal insulation on external stress corrosion cracking tendency of austenitic stainless steel astm c 69295a was used to research the effect of halogens and inhibitors on the external stress corrosion cracking escc of type 304 stainless steel as it applies to the insulation industry. Sustainability of ss 904l vs ss 316 stainless steel 904l. The two most common stainless steel grades are 304 and 316. Stress corrosion cracking scc is characterized by cracks propagating either. Chloride stress corrosion cracking scc of type 304 and 304l austenitic stainless steels ss was studied by a constant load method in air at a temperature of 353 k with relative humidity rh of. Stainless 316 contains more nickel than stainless 304, while 304 contains more chromium than 316. They also published a stainless steel products manual that listed these designations and the typical chemical analysis and mechanical and physical properties of each individual grade.
There is an additional risk of stress corrosion cracking scc at higher temperatures. Film and ph effects in the stress corrosion cracking of. Type 304, with its chromiumnickel content and low carbon, is the most versatile and widely used of the austenitic stainless steels. Localized corrosion and stress corrosion cracking of stainless steels. The resistance of types 304 and 316 stainless steels to. A precursor of stress corrosion cracking in chloridebearing environments is pitting corrosion, occurring if the stainless steel is not sufficiently resistant to pitting. Stainless steels 304l and 316l exhibit pitting in iodine solutions or solutions exposed to iodine vapor, as. Selection stainless steel for handling sodium hydroxide naoh. Duplex stainless steel improved corrosion and more importantly, stress corrosion cracking resistance higher strength and hardness. Chloride stress corrosion cracking in austenitic stainless steel.
The most basic difference between the grades of steel is the presence of molybdenum in stainless 316. Potentialtemperature domains in which purely igscc, simultaneous igscc and tgscc, and igscc accompanied by pitting corrosion have been determined. 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. There can be a risk of stress corrosion cracking scc attack at higher temperatures, which is common to both the 304 and. Sour service limits of dualcertified 316 316l steel twi. Selection of stainless steels for water tank applications. This provides improved fatigue and wear resistance higher tensile and yield strength compared to the austenitics translates into thinner walls and less weight which can offset the cost to some extent. It is found that the stress vs timetofailure curves for both alloys are divided into three regions that are dominated by either stress, scc, or corrosion.
Both 304 and 316 stainless steel types are resistant to a wide range of concentration and temperature. Summary of available data for estimating chlorideinduced scc. The most essential characteristic of stainless steel is its corrosion resistance. A comparison of the behaviour of these steels in the form of tubes with those made of sheets under stress corrosion cracking scc tests was discussed. Sep 21, 2018 sae 304 stainless steel is probably the most common stainless steel alloy in use today. Table 6 lists the relative corrosion resistance of the aisi standard numbered stainless steels in seven broad categories of corrosive environments. Stainless steel 316 and 316l grade 316 is the standard molybdenumbearing grade, second inoverall volume production to 304 amongst the austenitic stainless steels. The most essential characteristic of stainless steel is its corrosion. A literature survey has been performed to identify scc crack growth rate. Chloride stress corrosion cracking in austenitic stainless. Stainless steel s rustresistant properties make it an ideal material for many applications including building materials that enhance modern aesthetic appeal. Deterioration by clscc can lead to failures that have the potential to release stored energy andor hazardous substances. This diagram figure 1 is analogous to a similar diagram for caustic. The ss 904l alloy contains a combination of chromium and molybdenum which produces an improved level of resistance to pitting and crevice corrosion by chlorides compared to ss 316 stainless steel.
Type 316 is an austenitic chromiumnickel stainless and heatresisting steel with superior corrosion resistance as compared to other chromiumnickel steels when exposed to. Both steels are durable and provide excellent resistance to corrosion and rust. In most environments, the ppm are so small the effects on stainless. The stress corrosion cracking susceptibility of aisi types 304 and 316 ss tubes. Two of the criteria for scc in stainless steel have been met temperature over. Selection of stainless steels for handling sodium hypochlorite naocl.
Type 304 stainless steel an overview sciencedirect topics. The main hazard is stress corrosion cracking scc, which relies on tensile stresses as part of the failure mechanism. To add this web app to the home screen open the browser option menu and tap on add to homescreen. Pdf stress corrosion cracking of stainless steel components in. Effect of halogens and inhibitors on the external stress. Duplex stainless steel comparison to stainless steel 316l. In most environments, the ppm are so small the effects on stainless are minute. On the stress corrosion cracking and hydrogen embrittlement. Stress corrosion cracking of aisi 304 and 316 stainless. There can be a risk of stress corrosion cracking scc. This study concerns corrosion and stress corrosion cracking scc initiation of type 304 and 316 austenitic stainless steels in activated methyl diethanol amine amdea solution. Stress corrosion cracking facts and how to reduce the risk.
It is not as conductive, both electrically and thermally, as carbon steel and it is not magnetic. The material used in the present study is 304 stainless steel, the chemical composition of it is shown in table i. Austenitic steels of type astm 304 and 316 austenitic steels have limited resistance to stress corrosion cracking scc, even at very low chloride contents and temperatures. The stress corrosion cracking scc and hydrogen embrittlement he. Other factors, such as ph, chloride concentration, and temperature also affect the potential for steel cracking. The rate of stress corrosion cracking scc was measured for nonsensitized, coldworked type 316 uns s31600 and type 304 uns s30400 in both hydrogenated pressurized water reactor pwr primary. Pdf stress corrosion cracking of austenitic stainless. 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. Stainless steel grades, such as the 304 or 316 types are generally suitable for storing and handling cold or unheated drinking towns waters. Metline industries supplies high quality duplex stainless steel 2205 rods and bars, as well as stainless steel 316l stainless steel bars and rods. Stress corrosion cracking scc is the growth of crack formation in a corrosive environment. Stainless steel is a big family and wide used metal material, there are various grades in this group, these grades have special chemical composition and properties to suit various applications, two of them are remarkable grades, namely, 304 stainless steel and 316 stainless steel, the most stainless steel grades are used all over the world. This mode of attack is termed stress corrosion cracking scc. Thierry, lowtemperature stress corrosion cracking of stainless steels in the atmosphere in.
Stainless steels are more resistant to general corrosion compared with carbon steel. Chloride stress corrosion cracking and 316 stainless steel. With respect to pitting and crevice corrosion resistance the high chromium, molybdenum and nitrogen contents in duplex grades provide very good resistance to chlorideinduced localized corrosion in aqueous environments. There can be a risk of stress corrosion cracking scc attack at higher temperatures. However, molybdenum itself does not get incorporated in the passive film. Stress corrosion cracking of aisi 304 and aisi 316 austenitic. The stress corrosion cracking scc and hydrogen embrittlement he behaviors for types 304, 310, and 316 austenitic stainless steels were investigated in boiling saturated magnesium chloride solutions using a constant load method under different conditions including test temperature, applied stress, and sensitization. With regard to the safe temperature for carbon steel, the reader should look at the curve in figure 1. They also published a stainless steel products manual that listed these designations and the typical chemical analysis and mechanical and physical properties of.
Chloride stress corrosion involves selective attack of a metal along its grain boundaries. Both of type 304 and type 316 stainless steels showed quite similar behavior. Since pricing and corrosion resistance are both equally important when deciding a grade for a particular selection. It is thought to start with chromium carbide deposits along grain boundaries that leave the metal open to corrosion. The combination of the high molybdenum and chromium content, along with the addition of tungsten, make alloy c276 nickel alloy plate highly resistant to chloride stress corrosion cracking, pitting, crevice corrosion and general corrosion. 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 304 304l to stress corrosion cracking in sodium chloride solutions. The duplex stainless steels were developed to exhibit comparable general corrosion resistance as 316ss, but with. I would like to know about the possibilities of stress corrosion cracking for ss 304l at following thermal hydraulic conditions. Stainless steel types 304 and 316 can be considered resistant below 80 degc, up to the limit of solubility. Fourpoint bend testing on parent and welded dualcertified 316 316l stainless steel, to iso 151563. Like pitting corrosion this occurs in chloride environments, but it is possible for scc to take place with only traces of chlorides, so long as the temperature is over about 60 c, and so long as a. Type 304 and 316 since it is highly resistant to chloride stress corrosion cracking and is about twice as strong. Stress corrosion cracking of aisi 304 and 316 stainless steels in. Pdf corrosion and stress corrosion cracking initiation.
Facts in brief about stress corrosion cracking scc stress corrosion cracking scc is characterized by cracks propagating either transgranularly or intergranularly. The stress corrosion cracking susceptibility of aisi types 304 and 316 ss tubes with different heat treatments were investigated in lithiated water at 350c. Chloride stress corrosion cracking and 316 stainless steel moltenmetal chemical 20 jul 11 07. Duplex alloys are more resistant to chloride stress corrosion cracking than types 304 and 316. Stress corrosion cracking of sensitized type 304 stainless steel in high temperature chloride solutions l. Stress corrosion also called stress corrosion cracking or chloride stress corrosion. Type 304 alloys are all modications of the 18% chromium, 8% nickel austenitic alloy. Stress corrosion cracking scc is a common issue with many specialty alloys. Stress relieving removes such residual tensile stresses and so improves the scc resistance.
How to select the right stainless steel for adequate corrosion resistance structural applications other applications 5. The most common type of stress corrosion cracking in stainless steels occurs in chloride environments, which will be the focus of. Although no stainless steel grade is totally immune to chloride scc, the relative. An industry value that has been developed is nace mr01. The most common environmental exposure condition responsible for scc of stainless steels is the presence of chlorides. Scc is highly chemically specific in that certain alloys are likely.
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