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The inhibiting effect of N-furfuryl-N'-phenyl thiourea (FPTU) on the corrosion of mild steel in aqueous solutions of 0.05 and 0.1MHCl, as well as 0.025 and 0.05 M H2SO4 has been demonstrated using the potentiodynamic polarization technique. The polarization data showed that FPTU acts as an efficient anodic inhibitor for mild steel in both acid solutions. Avery high inhibition efficiency was evidenced in both acid solutions and it was found to vary with the concentration of the inhibitor and temperature. The obtained kinetic parameters of adsorption revealed spontaneous adsorption and a strong interaction of FPTU with the mild steel surface. .

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Weldments of AISI grade 316 stainless steel, having a ferrite content of 4-6% and a variety of nitrogen concentrations were prepared using a modified element implant technique. Charpy impact specimens prepared from these weldments were subjected to a variety of aging treatments. Impact toughness decreases with aging time at all aging temperatures. Nitrogen is found to be beneficial to toughness. An empirical relation connecting the aging temperature, aging time and nitrogen content with toughness has been developed which can be used to estimate the time for embrittlement.

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Simulated weldments of AISI grade 304 stainless steel having a ferrite content of 4-6% with three levels of nitrogen ( 0?03, 0?08, and 0?11 wt-%) were prepared using a modified elemental implant technique. From these weldments, subsize Charpy impact specimens were prepared and subjected to aging treatment at different temperatures, 623-748 K, and for different times, 1000-5000 h. Impact toughness curves for these aged samples were generated by testing at various temperatures from 77 K to 300 K. From the impact curves the upper shelf energy (USE) and lower shelf energy (LSE) were determined. It was observed that both USE and LSE decreased with aging time at all temperatures. Nitrogen seems to offer a beneficial effect as far as impact toughness is concerned, as both USE and LSE values increased with increasing nitrogen content. The worst aging conditions were identified as 748 K, 2000 h at the lowest nitrogen level of 0?03 wt-%. An empirical relation connecting the aging temperature, aging time, and nitrogen content to the LSE was developed, which can be used to predict the time for embrittlement at a given nitrogen level and aging temperature.

The stress corrosion cracking (SCC) characteristics of Zircaloy-2 sheets in methanol-0.4 vol. pct. hydrochloric acid have been studied in the annealed and cold-rolled conditions using longitudinal and transverse specimens. The times to failure for annealed longitudinal specimens were longer than those for similarly tested transverse specimens at stress levels below -45% UTS. The cold-rolled specimens developed resistance to SCC, but failed totally by cleavage when notched, unlike annealed specimens which failed by intergranular initiation followed by cleavage. The crystallographic texture developed by cold rolling is such that the crack initiation is difficult because of quicker passivation characteristics of the crack initiating plane. The texture also gives unfavourable orientation of slip and twinning planes with respect to tensile axis. The crack initiating planes are identified with the help of X-ray pole figures. The apparent activation energy is found to be texture dependent at a given stress level. On the basis of apparent activation energy measurements, dynamic tests at constant cross-head speeds and electrochemical measurements, the mechanism of SCC is identified to be the one involving stress-aided anodic dissolution.Die Spannungsriakorrosion von Zircaloy-2-Blech wurde unter Verwendung von gegliihten und kaltgewalzten, in Langs-und Querrichtung ausgeglichenen Proben in 0,4 Vo1.-% methanolischer Salzsaurelosung untersucht. Die Zeit bis zur RiRbildung war bei den Langsproben langer als bei Querproben unter sonst gleichen Bedingungen (Belastung unter 45% der Zugfestigkeit). Die kaltgewalzten Proben waren zwar gegen SpannungsriRkorrosion bestandig, erlitten jedoch Spaltbruch, wenn sie gekerbt wurden, wahrend die gegliihten Proben ein anfangliches interkristallines RiRstadium mit anschlieflendem Spaltbruch zeigten. Durch das Kaltwalzen wird eine Kristalltextur gebildet, welche die ReiBeinleitung erschwert, da die riRauslosenden Ebenen sich rasch passivieren. Diese Textur enthalt auch Gleit-und Zwillingsebenen mit gegeniiber der Zugachse ungiinstiger Orientierung. Die riaauslosenden Ebenen werden mit Hilfe der Rontgen-Polfiguren identifiziert. Die scheinbare Aktivierungsenergie ist bei gegebener Belastung texturabhangig. Aufgrund der gemessenen scheinbaren Aktivierungsenergie, der dynamischen Untersuchungen mit konstanter Dehnung und der elektrochemischen Messungen wird der Mechanismus der Spannungsriakorrosion als durch Belastung geforderte anodische Auflosung identifiziert.