Corrosion-resistance stress cracking

Duplex stainless steels (ca 4% nickel, 23% chrome) have been identified as having potential appHcation to nitric acid service (75). Because they have a lower nickel and higher chromium content than typical austenitic steels, they provide the ductabdity of austenitic SS and the stress—corrosion cracking resistance of ferritic SS. The higher strength and corrosion resistance of duplex steel offer potential cost advantages as a material of constmction for absorption columns (see CORROSION AND CORROSION CONTROL). 

Where, for example, chloride stress-corrosion cracking is a risk the process temperature becomes a critical variable. Thus it may be more economic to lower the process temperature to below 70°C, a practical threshold for chloride stress-corrosion cracking, than to incur the extra expense of using stress-corrosion cracking-resistant materials of construction. 

Alloys of high nickel content also have improved chloride stress-corrosion cracking resistance and Incolloy 825 has replaced type 321 stainless steel for steam bellows on some plants. Occasionally cracking of the latter was experienced due to chloride-contaminated steam condensing in the convolutions on shut-down and being re-evaporated at start-up. 

New alloys with improved corrosion-resistance characteristics are continually being marketed, and are aimed at solving a particular problem, e.g. improved stress-corrosion cracking resistance in the case of stainless steels improved pitting resistance or less susceptibility to welding difficulties. 

NACE MR 0175 Sulfide stress corrosion cracking resistant metallic materials for oil field equipment ... 

NACE MR0175-2003 - Metals for Sulphide Stress Cracking and Stress Corrosion Cracking resistance in Sour Oilfield Environments (published by NACE), a standard which is now already withdrawn. 

Duplex stainless steels (4% nickel, 23% chrome) may offer cost advantages in absorption columns. These materials provide the ductability of austenitic stainless and the stress-corrosion cracking resistance of ferritic stainless steel104. 

Media considerations. SCC tests can be divided into those conducted in natural environments, such as atmospheric exposure tests and seawater immersion tests, and those which are conducted under laboratory conditions or other fabricating operations. The principal disadvantage of atmospheric exposure tests is the comparatively long time required for their completion however, they are reliable since they can reflect the projected use. There is a standard practice for evaluating stress-corrosion cracking resistance of metals and alloys by alternate immersion in a solution of NaCl 3.5%, pH 6.5. For spray testing, ASTM B-117, 2003 states the relevant conditions for conducting the test. (ASTM G44)4... 

NAiCE Standard MR0175, Sulfide Stress Corrosion Cracking Resistant Metallic Material for Oilfield Equipment," MACE, Houston, TX. latest revisron. 

With the desired microstructure, these alloys are resistant to hydrogen stress cracking and much more resistant to chloride stress corrosion cracking than are the austenitic stainless steels. (The threshold temperature for chloride stress corrosion cracking of duplex alloys in neutral pH aqueous chlorides is about 300°F [150°C].) The chloride stress corrosion cracking resistance of the duplex alloys is similar to that of superaustenitic alloys such as Alloy AL-6XN. Because they contain about 50% ferrite, the duplex stainless steels are more susceptible to hydrogen embrittlement. 

R.N. Parkins, P.W. Slattery, and B. Poulson, The Effects of Alloying Additions to Ferritic Steels upon Stress Corrosion Cracking Resistance, Corrosion, Vol 37, 1981, p 650... 

T7xx) designed to provide a good combination of strength, fracture toughness, and stress-corrosion cracking resistance (Ref 1). The work described in this section was performed on... 

G. Frankel and Z. Xia, Localized Corrosion and Stress Corrosion Cracking Resistance of Friction Stir Welded Aluminum Alloy 5454, Corrosion, Vol 55 (No. 2), Feb 1999, p 139-150... 

M. Salagaras, P. Bushell, and B. Hinton, Effects of Friction Stir Welding on the General Corrosion and Stress Corrosion Cracking Resistance of Aluminum Alloy 7075-T651, Paper 9, Proc. Int. Conf Tech. Dev. Weld. Def Equip., March... 

NACE Technical Committee, Task Group T-lF-23, Stress corrosion cracking resistance of pipeline welds a special report on sulfide stress cracking resistance of pipeline welds. Mater. Perform. 32 (1993) 58-64. 

M. A. Arafin, J. A. Szpunar, A new understanding of intergranular stress corrosion cracking resistance of pipehne steel through grain boundary character and crystaUographic texture studies, Corros. Sci. 51 (2009) 119-128. 

Al-Tal, M. Badran, O. O. The effect of shot peening on the stress corrosion cracking resistance of 304 AISI stainless steel immersed in NaCl solution. Proc. 1st Jordanian International Conference of Materials Science and Engineering, Al-Balqa Applied University, Al-Salt, Jordan, 3-5 May 2005, pp. 138-150. 

Lower stress corrosion cracking resistance when compared to Alloy 33... 

ASTM G36-87 (1987) Standard Practice for Evaluating Stress Corrosion Cracking Resistance of Metals and Alloys in a Boiling Magnesium Chloride Solution. 

Figure 1136 Effect of heat treatment on mechanical strength and stress corrosion cracking resistance of aluminum alloys (schematic).

Near-alpha alloy with excellent weldability, seawater stress corrosion cracking resistance, and high dynamic toughness. 

---