Weldments stress-corrosion cracking

Additionally, specific environmental conditions can induce localized corrosion such as temperature, conductivity of the corrosive fluid, or thickness of the liquid corrosive film in contact with the metal. In some cases, both metallurgical and geometric factors will influence behavior, such as in stress-corrosion cracking. Preferential weldment corrosion of carbon steels has been investigated since the 1950s, commencing with the problems on icebreakers, but the problem continues today in different applications. (Bond)5... 

Stress corrosion cracking in heat treated weldments indicates that postweld heat treatments are sometimes ineffective. Sometimes this result can be attribnted to microalloying. (Microalloying is discnssed later.) In some cases, subsequent stress corrosion cracking can be traced to an improperly... 

Some engineering codes allow low-temperature PWHTs if the weldment is held at the lower temperature for an extended time. Such PWHTs should not be permitted to avoid or minimize the risk of stress corrosion cracking. 

A form of cracking which can occur in a wide range of materials caused by the combined action of stress and a chemically aggressive environment. In ferritic steels, certain forms of stress corrosion cracking are the result of embrittlement by hydrogen introduced chemically from the environment and residual stresses resulting from welding. Restrictions on the hardness of steel and weldments are made to avoid the problem. 

Liquid penetrants Cracks, gouges, porosity, laps, and seams open to a surface Castings, forgings, weldments, and components subject to fatigue or stress-corrosion cracking Inexpensive easy to apply portable easily interpreted Flaw must be open to an accessible surface, level of detectability operator-dependent... 

D. E, Jordan, Stress-Corrosion Cracking of Nickel-Base Alloy Weldments, International Institute of Welding Annual Assembly, Montreal (1990). 

While many laboratory tests for resistance of metals to stress corrosion cracking have been developed, only a few tests are amenable to actual in-situ testing in seawater. These primarily consist of the exposure of statically stressed type test specimens such as described in ASTM G 30, G 38, G 39, and ISO 7539-2, ISO 7539-3, and ISO 7539-5. In addition, welded specimens such as described in ASTM G 58 are excellent for evaluation of the stress corrosion resistance of weldments in simple immersion tests. Evaluation of corrosion fatigue is usually limited to laboratory testing. 

Lyle, F. F., Stress Corrosion Cracking Susceptibility of Weldments in Duplex Stainless Steels, MTI Publication No 33, National Association of Corrosion Engineers, Houston TX, 1989, p. 1. 

A Pipe Test Method for Evaluating the Stress Corrosion Cracking Behaviour of Welded Type 304 Stainless Steel Pipes Properties of steel weldments for elevated temperature pressure containment applications, 1978, 91-101 - Met. A., 7911-72 0370... 

PB Srinivasan, R Zettler, C Blawert, W Dietzel, A study on the effect of plasma electrolytic oxidation on the stress corrosion cracking behaviour of a wrought AZ61 magnesium alloy and its friction stir weldment. Materials Characterization, 2009,... 

PB Srinivasan, S Riekehr, C Blawert, W Dietzel, M Kocak, Slow strain rate stress corrosion cracking behaviour of as-welded and plasma electrolytic oxidation treated AZ31HP magnesium alloy autogenous laser beam weldment. Materials Science... 

It has better overall corrosion resistance in oxidizing corrosives than C-4, C-276, and 625 aUoys, outstanding resistance to localized corrosion, and excellent resistance to stress corrosion cracking. It is the best alloy to use as universal weld filler metal to resist corrosion of weldments. 

Coupons may be used to determine the average fluid corrosivity by measurement of weight loss (See Figure 8.1). Susceptibility to pitting, bimetallic corrosion, stress corrosion cracking, crevice corrosion, corrosion in weldments or heat affected zones (HAZ), hydrogen embrittlement, scaling, erosion, and cavitation may also be determined. The method facilitates an assessment of the corrosivity of an environment with respect to the specific material of construction of that part of the plant. 

For purposes other than weight loss from a single metal or alloy, (e.g. bimetallic corrosion, weldment corrosion, stress corrosion cracking), novel coupon designs wfll be required, appropriate to the corrosion phenomenon being evaluated. 

D.O. Harris, D.D. Dedia, E.D. Eason, and S.D. Patterson, Probability of failure in BWR reactor coolant piping probabilistic treatment of stress corrosion cracking in 304 and 316 NG BWR piping weldments, NUREG/CR-4792, December, 1986. 

A true ASME Section XI type inspection baseline does not exist for the SRS reactors due to the vintage of the plant and other limitations. Therefore, the data from each scheduled inspection will be analyzed to form an equivalent baseline. Examination methods and SRS categorization of weldments based on intergranular stress corrosion cracking (IGSCC) susceptibility are described in detail in Section III of the ISI plan. Inspection schedules, examination methods, frequency, and successive intervals for piping, heat exchangers, and reactor welds are described in the tables of the plan. (The-evaluation of reactor tank UT examinations, which are required for restart, is discussed below. 

Weldments subjected to corrosive attack over a period of time may crack adjacent to the weld seams if the residual stresses are not removed. Gas—tungsten arc welding and gas—metal arc welding ate recommended for joining magnesium, the former for thinner materials and the latter for thicker materials. Maintaining a protective atmosphere is a critical issue in welding these alloys. 

The American Petroleum Institute and the National Association of Corrosion Engineers publish documents that indicate whether weldments made with certain wire/flux combinations have experienced failure in HjS environments under conditions in which failures were unexpected. Weldments with high manganese and silicon contents have been shown to be very susceptible to sulfide stress cracking at levels of hardness at or below 22 HRC, even after thermal treatments. 

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