Shot peening piston crown?

[Bill Chase]

Fwiw, every tank is tested to 450 psi, it must hold it for 60 seconds if not it gets inspected and reworked or scrapped. Occasionally they blow up. Probably one out of every 5,000 units fails in testing. They are pretty tough for starting life as thin aluminum blanks

[Dan Timberlake]

like juhana (and Mil Spec S-13165) said.

"3.3.10 Post Treatments. No manufacturing operations which relieve stresses developed by peening or which develop detrimental residual stresses shall be permitted after shot peening. When peened parts are heated after shot peening as for baking of protective coatings, to relieve hydrogen embrittlement after electroplating, or other thermal treatment, the temperatures employed shall be limited as follows (see 6.13):
Material Temperature
Steel Parts* 475° F Maximum
Stainless Steel Parts** 750° F Maximum
Aluminum Alloy Parts 200° F Maximum
Magnesium Alloy Parts 200° F Maximum
Titanium Alloy Parts 600° F Maximum
Nickel Alloy Parts 1000° F Maximum
Cobalt Alloy Parts 1000° F Maximum "

[engineguyBill]

I don't have any first-hand experience with this subject, but I would be concerned that the shot peening process might cause the aluminum piston crown to become brittle and subject to shallow cracks. Don't know, just contemplating . . . . . . . . .

[Schurkey]

like juhana (and Mil Spec S-13165) said.

"3.3.10 Post Treatments. No manufacturing operations which relieve stresses developed by peening or which develop detrimental residual stresses shall be permitted after shot peening. When peened parts are heated after shot peening as for baking of protective coatings, to relieve hydrogen embrittlement after electroplating, or other thermal treatment, the temperatures employed shall be limited as follows (see 6.13):
Material Temperature
Aluminum Alloy Parts 200° F Maximum

Well, that's the end of shot-peening piston crowns. They're going to get WAY hotter than 200 degrees F.

[pamotorman]

shot peen no but bead blast yes so the crown coats quickly to keep heat in the combustion area as an engine is a heat pump.