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Graph of Coupon A
B
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Graph of Coupon C
D
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The coupons measure approximately .75" x .25" and are 3" long. Center sections were measured, plotted, then electro-polished to remove material. X-ray diffraction was again used to measure stress and the process repeated until the value of KSI crossed the zero "y" axis. From these plotted points curves
are drawn.
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H-13 Premium Grade |
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Oil Quenched |
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46-48Rc |
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Milled Finish |
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Polished |
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+1000 degrees F |
The small square in the center of each coupon is the area were successive compressive
residual stress readings were done by electro-polishing the surface. This method of polishing does not disturb the existing value of stress.
The microstructure of a ferritic nitrocarburized H-13 surface shows an epsilon compound layer that is .0002" to .0008" in depth followed by the diffused carbon/nitrogen layer ranging in depth from .004" to .008" (dependent on processing criteria) which gradually dissipates. |
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If the
diffusion is
allowed to become too thick, spalling can result. We therefore have
developed special recipes for all types of hot work steels that do not result in
what you view here. If we were to do a
maximum of our T-41H MetaLL ifeÒ
process over the TL08 TherMaLLifeÒ recipe, you would see what we have here.
Click on coupon to view a section |
