Surface hardening of diy cast alloy?

[julianf]

The scrap I have is 5005. I realize it's not a casting alloy, but it's what I have (in excess).

All I've done so far is melt it, pour it, and cut parts out of the ingots on the lathe.

The surface isn't hugely attractive or scratch resistant etc.

I don't really want to colour the part. Natural anodizing may be a consideration but I would rather a peened finish.


Does a peened finish increase scratch resistance and limit absorption of environmental contaminants? I'm thinking yes, but wondering to what sort of degree?

And is this achievable on a diy level with a couple of 3hp compressors and a pressure pot?

If so, what blast media would I need to acquire? Id ideally like something that would last rather than a disposable media, even if it means spending more in the short term.

Thank you.

 

[Morrisman]

Not quite peening, but I had several Japanese motorcycle parts bead blasted many years ago, brake calipers, MC etc, gave them a shot of WD40, and they never corroded again, even ridden daily through a couple of U.K. winters. I could only imagine the bead blasting had hammered down the surface and sealed it somehow.

 

[Bladevane]

I know bead blasting on ferrous components puts the surface into compression hence increasing properties. This was done on gas turbine blades, diaphragms etc. Not sure about aluminium alloys though.

 

[pressbrake1]

Not quite peening, but I had several Japanese motorcycle parts bead blasted many years ago, brake calipers, MC etc, gave them a shot of WD40, and they never corroded again, even ridden daily through a couple of U.K. winters. I could only imagine the bead blasting had hammered down the surface and sealed it somehow.

Silicon inclusion

 

[bricol]

I've read about manual peening to improve Rover K-series heads where a fire-ring would sit, and I've had steel gears peened to increase strength and life.

Peening to improve the surface strength is pretty specific task - not sure you could do a reliable job at home.

 

[Seadog]

Rocker arms, condors, and, I'm sure many other stressed pieces have been shot peened for increased resistance to surface fatigue.

 

[julianf]

The parts I want to adjust are not parts that have mechanical concern. I'm wanting to alter the surface for cosmetic longevity.

Structurally it doesn't matter what they look like, but, if I can't make them look (and stay looking) pretty than I may as well quit now.

 

[Wildefalcon]

Would a needle gun work?

 

[brightspark]

bead blasting will remove light corrosion and peen the surface without damage. the beads are glass spheres and will leave a satin finish on alloy or steel . heres a few bits ive blasted. all were rusted like the 1st backplate in picture

 

[brightspark]

beads are quite expensive and reusable but its best to clean most of the crap of first to keep them clean .i lightly sand blast stuff first then bead if tolerance isnt critical

 

[julianf]

beads are quite expensive and reusable but its best to clean most of the crap of first to keep them clean .i lightly sand blast stuff first then bead if tolerance isnt critical

Thank you.

The parts will be "new" so not especially contaminated. Maybe "sealing" the surface would have been a better way to describe what im wanting to do? It sounds like glass beads are probably what i should try.

Stainless shot is no good?

 

[brightspark]

Thank you.

The parts will be "new" so not especially contaminated. Maybe "sealing" the surface would have been a better way to describe what im wanting to do? It sounds like glass beads are probably what i should try.

Stainless shot is no good?

not for making a smooth finish anything apart from beads will etch the surface generaly to paint things