AWS G2.3M／G2.3 pdf free download

AWS G2.3M／G2.3 pdf free download.Guide for the Joining of Solid Solution Austenitic Stainless Steels.
ferrite. A solid solution phase with the body-centered cubic (BCC) crystal structure. The term “ferrite” as discussed in this document is “delta ferrite.” The presence of ferrite during solidification increases resistance to weld metal solidification cracking hut can also promote formation of brittle intermetallics such as sigma phase during subsequent high temperature exposure. Delta ferrite ftrms during the solidification of molten stainless steels containing iron alloyed with ferrite-promoting elements including chromium, molybdenum, silicon, niobium, titanium, aluminum, vanadium, or tungsten.
free iron. Iron particles or iron deposits on the material’s surface not originating from the stainless steel base metal. heat (of material). A finite quantity of material melted and produced at a mill at one time.
heat-affected zone (HAZ). The portion of base metal that has had its mechanical properties or microstructure altered by the heat of welding, brazing. soldering, or thermal cutting.
heat tint. Also called discoloration. Any change in surface color from that of the unaffected base metal: usually associated with oxidation. Heat tint may occur on the weld, weld heat-affected zone (IIAZ). or base metal as a result of heating from welding or other thermal processes. Heat tint colors may range from pale bluish-gray to deep blue, and from a pale straw color to a black crusty coating.
hot crack. A crack formed at temperatures near the completion of solidification in weld metal or the partially meted zone. See also liguation cracking and weld metal solidification cracking.
knifeline attack (KLA). Corrosion that occurs in a very narrow region directly adjacent to the weld fusion line. Stable carbides (niobium or titanium carbides) in that region are dissolved (put into solution) from the heat of welding, but do 1101 reprecipilate with carbon during welding or cooling. Instead, chromium carhides form in that region during high-temperature exposure or when cooling rates after welding are too slow. The precipitation of chromium carbide sensitizes the region making it susceptible to KLA unless a stabilization anneal is performed. The stabilization anneal temperature is sufficient to reprecipitale the niobium or titanium carbides, thus removing the sensitization ciTect (see Figure 5.4b).
hquation cracking. A form of hot cracking that occurs in the heat-affected zone (HAZ) of single pass welds, or in reheated weld metal in multipass welds due to ti)rmation of liquid films along grain boundaries in the partially melted zone adjacent to the fusion line. Liquation results from the segregation of impurities to grain boundaries or by constitutional liquation e.g., partial melting of NbC or TiC. Can be diflicult to detect and typically appear as small cracks in the HAZ or “micro fissures” in prior weld passes.
magnetic. As used in this document, the ability of a magnet to be attracted to the material being tested.
passivation. The chemical treatment of a stainless steel with a mild oxidant so as to remove free iron from the surface and speed up the process of forming a protective/passive layer. However, passivation is not efTective for the removal of heat tint or oxide scale on stainless steel.
phase. A portion of a material that has roughly the same composition, structure and atomic arrangement throughout. and having a distinct boundary between it and any surrounding or adjoining phases.
pickling. The removal of highly adherent oxides using aggressive acid-based solutions. These oxides include heat tint formed adjacent to welds as well as thicker oxide layers formed during longer term, high-temperature exposure (e.g.. furnace heat treatments performed without protective atmospheres. mill scales from rolling and forging operations. and high-temperature service exposure). Pickling is also elTective ftr removing free iron.
precipitate prisi-p-’tãt\ i’l. The process of forming small, discrete particles (phases) (usually formed at elevated temperatures) within a material’s structure.
precipitate \pri-’si-p-tt\ n. Small, discrete particles (phases) usually formed at elevated temperatures within a material’s structure. Depending on the alloy, their presence can either be intentional and beneficial, or. undesired and potentially detrimental.
reheat cracking. Weld or heat-affected zone cracking that occurs due to rupture resulting from grain boundary sliding during the heating sequence of posiweld heat treatment (PWHT) or heating of previous passes in muttipass weldments.AWS G2.3M／G2.3 pdf download.