Partial weld around a pipe joint with clear heat affected zone. This is ASME SA106 Grade B steel pipe NPS 2.5 SCH 80 with J-grooved prepared ends. An automated TIG orbital welder made half an orbit before aborting. The heat affected zone is clearly visible because of the polished ends, even though it is generally innocuous in this material. (SA106 Grade B) Photo by Yannick Trottier, 2006.

A method of checking temperature is by the temper colors: A given temperature will leave a distinct color corresponding to that temperature on a freshly filed surface. (It should be noted that the presence of alloying elements in the steel affects the colors formed, and some of the higher alloy steels have no temper colors.) This temperature range is very evident in the picture above, at the outside edge of the temper color you can see the transition of all the colors and corresponding temperatures.

Temperature C     And          Color              
    204.4                     Faint Straw
    226                       Straw
    246.1                     Deep Straw
    282                       Bronze
                           Peacock
    590                       Full Blue
    640                       Light Blue

This is a retouched picture, which means that it has been digitally altered from its original version. Modifications: rotated. The original can be viewed here: Pipe root weld with HAZ.jpg: .

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