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#232 - 09/07/09 06:17 AM Almen strip variability and effect on intensity
alfredo Offline
Member

Registered: 08/28/08
Posts: 6
Loc: Madrid; Spain
I have detected different intensity measurements based on different strip hardness.
Altought the strip hardness meets always the spec (44-50 HRC), we have found what I understand significant differences (> 0,01 mm) in the measurement intensitty when we used strip in the lowset hardness range or in the upper hardness range.
The shot peening spec. is 0,15-0,2 mm Almen C; 100% coverage; shot size: 330. The part is a carburized gear.
Could anyone share its experince in this issue?

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#233 - 09/08/09 02:28 AM Re: Almen strip variability and effect on intensity
Dennis Offline
Member

Registered: 09/25/07
Posts: 11
Loc: The Netherlands
We have this experience as well and as a matter of fact I posted a question about it on this forum a while ago.

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#234 - 09/08/09 04:53 PM Re: Almen strip variability and effect on intensity
Walter Offline



Registered: 05/03/99
Posts: 158
Loc: East Hartford, CT, USA
We had the same problme a few years ago. When checking your hardness readings are they stable on the centerline of the strip, then taper off left / right of center?

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#235 - 09/10/09 06:51 AM Re: Almen strip variability and effect on intensity
alfredo Offline
Member

Registered: 08/28/08
Posts: 6
Loc: Madrid; Spain
Thank you for your suport.
1) We measure the hardness four times and take the average, and we usually measure at the centerline.
2) We have done a metalographic study of two Almen strips. We have seen some surface decarburization whitin 15 and 30 um. I assume that it is created during the hot rolling, and I think it could also affect the intensity result. The hardness variability between core and surface is practicaly null.

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