Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Pitting Tests

A study of the Alloy 2205 weld micro-structures revealed why high arc energies were found to be beneficial to pitting resistance. Many investigations have indicated that the presence of chromium nitrides in the ferrite phase lowers the resistance to pitting of the weld metal and the HAZ in duplex stainless steels. In this study, both weld metal and HAZ produced by low arc energies contained an [Pg.452]

The results of FeClj tests on submerged arc welds (SAW) showed that all top weld surfaces passed the test at 30°C (85 °F) without pitting attack, irrespective of arc energy in the range of 2 to 6kJ/mm (51 to 152kJ/inch). Surprisingly, the weld metal on the root side, which was the first to be deposited, did not pass the same test temperature. [Pg.453]

Therefore, the resistance of AUoy 2205 to pitting corrosion is dependent on several factors. First, CrjN precipitation in the coarse ferrite grains upon rapid cooling from temperatures above about 1200 °C (2190 °F) caused the most severe impairment to pitting resistance. This statement is supported by a great number of FeClj tests, as well as by potentiostatic pitting tests. [Pg.455]

Generally, it seems difficult to avoid CrjN precipitation in welded joints completely, particularly in the HAZ, the structure of which can be controlled only by the weld thermal cycle. From this point of view, it appears advisable to employ as high an arc energy as practical in each weld pass. In this way, the cooling rate wiU be slower (but not slow enough to encounter 475 °C (885 °F) embrittlement), and the reformation of austenite wiU clearly dominate over the precipitation of CrjN. [Pg.455]

In addition, if there were no restriction on maximum interpass temperature, the heat produced by previous weld passes could be used to decrease the cooling rate further in the critical temperature range above about 1000 °C (1830 °F). Preliminary tests with preheated work pieces have shown the significance of temperature in suppressing Cr-N precipitation. Currently, the maximum recommended interpass temperature for Alloy 2205 is 150 °C (300 °F). [Pg.455]


Wilde, B. E. and Williams, E., The Relevance of Accelerated Electrochemical Pitting Tests to the Long Term Pitting and Crevice Corrosion Behaviour of Stainless Steels in Marine Environments , J. Electrochem. Soc., 118, 1056 (1971)... [Pg.206]

Optimal salinity values directly influence the nature of the ionic groups, while temperature variations (PIT tests) strongly effect the oxyethylene linkages. [Pg.325]

Closed Pit Test (p C346-L Fig on p C347) OpenPi t Test (p C346-R C349-L)... [Pg.306]

Closed Chamber Test. Same as Closed Pit Test... [Pg.128]

The following four fragmentation tests have been u sed at Aberdeen Proving Ground (Ref 1) A)Closed Pit (orChamber) Test B)Open Pit Test C)Panel Test and D)Veloe ity of Fragments Test, whereas the closed pit test has been used at PicArsn. All of these tests are briefly described below ... [Pg.129]

Accdg to Ref 5, the closed pit test is somewhat unreliable because of loss of very small fragments, and because of secondary break-up of fragments by the effect of surrounding sand... [Pg.129]

B. Open Pit Test. This test is designed for the purpose of recovering a portion of the fragments of detonated bomb in such a manner rfcat they will be segregated into groups which correspond to various areas of the bomb -bpdy, nose or tail... [Pg.129]

In the open pit test only a small portion of the fragments hit the pit area, but since the angle subtended by the pit and the height of suspension are known, it is possible to compute all the info that can be obtained in a closed pit test... [Pg.132]

Open pit test may be conducted in conjunction with panel and fragment velocity tests (Ref 2, pp4-6) (See Fig under Panel Test)... [Pg.132]

There are four general types of fragmentation tests used by US Ord Dept enclosed Chamber or Pit Test. b)Open Pit Test, c)Panel Test, and d)Velociry Measurement Test. The Closed Chamber Test, as conducted at Picatinny Arsenal, is described in detail in Ref 7. The other three tests, as conducted at Aberdeen Proving Ground, are described in Ref 6. More information on fragmentation will be given in Vol III, under F Refs l)Stettbacher(1933),50-1 St 218-19 2)L.V.Clark,IEC 25, 1389-90( 1933) 3)A.Majrich F.Sorm,... [Pg.710]

The constant a contains stoichiometric factors and /c,p, which often are potential dependent. As a consequence of ohmic drops and a Kmitation of diffusion of corrosion products out of the pits, /c,p may decrease in later stages of pit growth with A detailed discussion yields a / -dependence of the nominal current density, that is, / = const t /, if the number of pits remains constant [2, 3] and an appropriately higher exponent for a still nonvanishingly small nucleation rate. As a consequence, a i = const I / to / = const t behavior is often found for long-time pitting tests. [Pg.313]

ASTM has standardized methods for investigation/evaluation of pitting attack and pitting testing in 6% FeCh (G46 and G48, respectively) [7.21]. [Pg.130]

Martinchek, G. A. and Ytiffe, M. R., CMS 110 Critical Pitting Test System Operator s Manual, GAMRY Instmments, Inc., Langhome, PA, 1992. [Pg.232]

Pitting corrosion will occur in most environments, particularly those containing the chloride ion. Pitting can be evaluated on virtually any specimen, but flat panels usually are used when this is the principal purpose of the test. ASTM G 1 describes surface preparation of specimens for pitting tests, while ASTM G 46 covers specimen evaluation after test. [Pg.554]


See other pages where Pitting Tests is mentioned: [Pg.455]    [Pg.660]    [Pg.286]    [Pg.1099]    [Pg.709]    [Pg.522]    [Pg.563]    [Pg.709]    [Pg.709]    [Pg.710]    [Pg.9]    [Pg.130]    [Pg.806]    [Pg.224]    [Pg.583]    [Pg.797]    [Pg.693]    [Pg.417]   


SEARCH



© 2024 chempedia.info