Quote:
Originally Posted by DavidJayUden
So, Don and Kyrie, is the metal part, once heated and straw colored, in any way preserved, hardened, strengthened, tempered or in any other way "improved" by the straw process? Or is it just colored?
dju
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Yes, it can be in "improved" condition. The original color was a result of "drawing" a previously heated , quenched or air cooled part, which was hardened- to a lower temperature to relieve stress and impart some property to it.
The straw on small parts at a low 430 degrees, still leaves them hard- but stress relieved. The "blue" of the small springs, like the sear spring and the mag spring is there due to the part being heated to a higher temperature to "make" the spring.
If you look at a clean early hold open, you will see a spot of stress relief by heating which shows a rainbow of color in about 1/4"- from yellow to brown/red to bright blue- then on the other side of the blue, back through the brown/red to the yellow straw. This leaves the major part of the hold open hard but tempers the heated area to relieve stress and prevent cracking.
The color is/was originally a consequence of the need to draw and not for decoration.
