Austenitic stainless steels intensity

Effect of stress intensity on the growth rate of stress-corrosion cracks in several austenitic stainless steels. Alloy compositions... 

Effect of molybdenum content on stress-corrosion threshold stress intensity of austenitic stainless steels. Source Ref 166... 

An interesting aspect of the expression (10) concerns the case of metals and passive alloys because the real polarization potential exhibits a discontinuity around the zone of transition from active to passive state. In fact, if Ip denotes the passivity current density, the value of the discontinuity is of the same order of magnitude as R,IpS because during this transition the current intensity falls very rapidly. The discontinuity may be very pronounced because the values of Ip, which depend on the type of metal, the environment and temperature, may be very high. In the case of the AISI 321H titanium-stabilized, austenitic stainless steel in 1 M HCIO4 -1- 0.3 M NaCl solutions at 25 °C, the value of Ip depends on the thermal history of the specimen [50]. In meiny instances it was found to be about 10 mAcm . ... 

Figure 1.17 shows SCC of a 2205 DSS sand separator cone in a pulp mill [49]. Duplex stainless steels possess a high-threshold stress intensity value, The duplex stainless steels that contain ferrite and austenite phases have better localized corrosion resistance than single-phase austenitic stainless steels in chloride-containing solutions and are used as structural materials in petrochemical, chemical, pulp and paper, power generation, oil, and gas industries. 

Figure 11.13 Crack-propagation rate versus stress intensity factor for a type-304 austenitic stainless steel (o) boiling 22% NaCl solution (105 °C) ( ) boiling 42% MgCl solution (130 °C).

Metallurgical factors can influence CF crack initiation and growth. Prominent in this regard are sensitization of grain boundaries in austenitic stainless steels [22,23], locally intense slip in aluminum alloys from dislocation interactions... 

Figure 3 Examples of crack velocity-stress intensity curves for SCC, showing the effects of alloy composition and cold work on SCC of austenitic stainless steels in a hot chloride solution. (From Ref 57. Courtesy of Pergamon Press.)...

Chromium carbide is among the compounds detected as precipitating the low temperature regions of liquid metal circuits, and the system Na—Cr—C is one of the most intensively studied systems There is some evidence that the most stable chromium carbide CrjsCg is formed at temperatures between 550 and 700 °C even in stainless steels, where the chemical activity of chromium is well below unity. This reaction is the chemical process causing the carburization of austenitic CrNi steels. CrjjCs precipitates in the surface zones of the material. 

The see resistance of duplex stainless steels is manifested as a high value ofthe threshold stress intensity, compared with austenitic steels [62] (Fig. 16). 

The SCC resistance of duplex stainless steels is manifested as a high value of the threshold stress intensity, l isco compared with austenitic steels [62] (Figure 11.16). This arises from the different chemistry of the individual phases, which gives them, individually, different optimal ranges of potential for SCC (higher for y, lower for a). 

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