Forged or Not, how to tell? 4a-gze Vs 1g-gze

[oldcorollas]

the way to do it would be to slice it in half, and then give it a macroetch..
usually this involves HF acid, but since i didn't want to use that before (restricted at my old uni), i used some different grinding/finishing techniques to bring out the grain structure.

next, you would check the microstructure, look for silicon particles and the like, and check the bulk composition, to see if it is closer to a casting or forging alloy.

then again, not all forging alloys are same composition, and same for casting.... so that is not 100% way to tell....

[The Witzl]

... in short, talk to the bloke who made the fecking things!!

[love ke70]

... in short, talk to the bloke who made the fecking things!!

i dont think god and stradlater are on talking terms right at the moment

[kingmick]

Don't suppose there is some way I can cast (excuse the pun) that methodology on the 1g-gze piston to determine if it's forged too?

Turn them upside down and take a picture and ill tell you what i think! The 4agze have wipe marks so the 1g should have the same if made alike!

[oldcorollas]

that just tells you that a die has been used and withdrawn. the smearing at the bottom of the pistons could have been made if it was forged or pressed when semi-solid...

much easier to ask the guy that made them

without that, it is a best guess from available evidence.....

they "look" to be forged or possibly pressed when semi-solid... not possible to differentiate by eye.

however, you can say they are cast and not forged when looking by eye

[kingmick]

As you can say that there similar to the 4agze piston!

4agze pistons are pressed when semi solid! Hence the semi-forged that has been running around for years!

[oldcorollas]

As you can say that there similar to the 4agze piston!
4agze pistons are pressed when semi solid! Hence the semi-forged that has been running around for years!

both rumours have been around for years, yet there has been no proof put forward, official or otherwise.

how do you know they are pressed when semi-solid?

these are HKS 5AG turbo pistons.... forged or semi-solid formed?


(and compare to 1G pistons someone?)

[kingmick]

semi solid or very nice blending!

[oldcorollas]

those are bead/shot blast to give the finish, along with machined centre dimple.
the top of the skirt is machined, but apart from that, how can you tell if it is forged or semi solid? both will have the same shape of die.

you seem pretty sure...

[kingmick]

Just smart i guess

[love ke70]

hes kingmick. he just knows

[stradlater]

I'd compare that to a 1g piston that I would have here, but I wouldn't have the faintest idea what to compare.

That 5ag piston (WTF Is a 5ag anyway?) looks mighty shmick, it really looks thin and delicate though? I'm sure it's not...

As for me asking the guy who made it, I'm tipping he's not gonna speak english, or even probably work at toyota anymore. :-)

I'm just talking aobut stock 1g pistons.

[kingmick]

Exactly the reason they blasted a semi solid! So it looks smick!

[oldcorollas]

Exactly the reason they blasted a semi solid! So it looks smick!

but mick, how do you know it is a semi-solid? what proof do you have apart from your assertion?

fwiw, there are forging (wrought) alloys with high silicon content they are used for pistons (such as... SAE4032) with similar silicon content to a hypereutectic alloy...

a semi-solid formed alloy will be a little different to both hypereutectic or a wrought alloy, because of the need to tightly control the liquidus and solidus of the alloy.

actually.... that piston was aftermarket treated
using WPC, which is effectively bead blast... so it was not supplied like that from HKS
http://www.wpctreatment.com/technical.htm

still stand by your assertion?

[kingmick]

I go visually after looking at many forged pistons for many years! i was right as we both know.
I was telling from the finish as its only visual !There is no need to bead blast a forged piston