both Dan and Marc explain the ideas about stress risers. I can’t doubt that they are right since they are two of the smartest guys here on the board. But still, i wonder about the work hardening idea, i’ve heard it quite a few times, and from personal experience with other metals it makes a lot of sense. When i go to get mine done i think i’ll talk to the machine shop a little, as well as try to get a glimpse at the shot they use.
i’m not sure if i’m understanding you right or not… but that sounds to me like reducing the “stress risers” idea like dan told me. I’m sure it does do that somewhat, but it seems logical to me that if that was the only thing it did, then we wouldn’t do it, because a real sand and polish would be MUCH more effective at reducing the stress risers, afterall, it would eliminate them instead of just bombard them down and together a little. [/B]
hey colin,
i just searched around the net and found some info on the theory of shot peening.
here’s a pdf file that explains some of the basics of the physics of the beneficial effects of shot peening and how it infact strengthens the metal. it explains that polishing and sanding does get rid of some of the stress risers etc, but shot peening which creates dimples in the metal. thus the metal below the dimple try to restore the fibers back to their original configuration and creates a “cold” highly compression stressed zone, and cracks will not propagate or originate in “compressively stressed zones”.
if you go to the bottom where it explains “connecting rods” it shows a comparison of polishing vs shot peening and shows a great increase in strength and time in shot peening vs polishing and honing. “A rough surface in compression will resist failures better than a smooth surface in tension”
i just searched around the net and found some info on the theory of shot peening.
here’s a pdf file that explains some of the basics of the physics of the beneficial effects of shot peening and how it infact strengthens the metal. it explains that polishing and sanding does get rid of some of the stress risers etc, but shot peening which creates dimples in the metal. thus the metal below the dimple try to restore the fibers back to their original configuration and creates a “cold” highly compression stressed zone, and cracks will not propagate or originate in “compressively stressed zones”.
if you go to the bottom where it explains “connecting rods” it shows a comparison of polishing vs shot peening and shows a great increase in strength and time in shot peening vs polishing and honing. “A rough surface in compression will resist failures better than a smooth surface in tension”
HTH [/B]
interesting info, but where’s the file so i can read the whole thing?
i’m reading through that article, and so far its some really good reading material. I’ve got to hit the sack pretty soon, so i doubt i’ll finish it tonight though. but for starters:
at the beginning:
“Benefits obtained by shot peening are the result of the effect of the compressive stress and the cold
working induced. Compressive stresses are beneficial in increasing resistance to fatigue failures,
corrosion fatigue, stress by corrosion cracking, hydrogen assisted cracking, fretting, galling and erosion
caused by cavitation. Benefits obtained due to cold working include work hardening, intergranular
corrosion resistance, surface texturing, closing of porosity and testing the bond of coatings. Both
compressive stresses and cold-worked effects are used in the application of shot peening in forming
metal parts.”
it takes about the two ways in which shot peening helps. both the way of reducing the stress risers, and the “cold working” which is basically what i was talking about. So, at first glance it appears both ideas are correct in their own respects.
interesting stuff, although a lot of it is a bit over my head. I’m sure i could understand it better if i just had a little more technical background in this kind of stuff.
Originally posted by Brunswck I think I already know the answer but i want to be sure.Will my throttle body(B17a)Bolt on to an ITR intake manifold or a skunk2 Intake manifold?