Rod spec question

[jpayne]

Those in the know...how does the following sound for Connecting Rod specification...not ford application.

•SAE certified 4340 Steel
•2 Piece forging
•Hardness of HRC33-38
•Dowelled cap for precision alignment
•X-RAY & Sonic tested
•Quenching and heat treated
•100% Magnafluxed
•Weight Matched Sets + - 1 gram
•Sizing + - 0.0001"


Any advice appreciated

Justin

[jsa]

Justin,

Be aware SAE 4340 is a fairly broard spec. Not all 4340 is created equal.

Paper specs look good though.

[jpayne]

cheers,

these are coming out of china for about 200AUD a set landed minimum order 50. likely to be cheap 4340?

JP

[Mark Cogan]

[jpayne]

cheers Mark,

Chemistry was not my strong point. perhaps the chemistry teacher reminding me on mr McGoo as a 16 and 17 yer old distratcetd me from my perioidic table...


Chemical Composition of Powder Forged Materials

HS150
Cu 3.06
C 0.5
Mn 0.31
S 0.12
FeB al.
HS160
Cu 3.03
C 0.57
Mn 0.33
S 0.12
Fe Bal.

Does this make any sense and anyone know how to cross reference it against known good compositions.

Justin

[jsa]

Powder forged, I'd be avoiding those.

[Mik Kay]

Here's my take on Chinese steel theory. Steel from China now days is pretty good and there processes are as good as anywhere in the world. The problem i find with China is some manufacturers lack the fine accuracy needed for today. I would be more worried about the dimensional accuracy of the rods more than the alloy makeup. As JSA has mentioned not all 4340 is equal and the chemical makeup of 4340 is only half the task, the accuracy of the whole heat treating process will play a major factor in determining how strong any alloy will become. Heat treating is the difference between steel that stretches and steel that does not.
As for the powder forging using HS 150/160 i really don't see the point of this other than cost. Comparing the 4340 alloy composition to both the HS alloys isn't even close. They both lack what makes them stronger with a high content of copper. A well heat treated 4340 can easily reach 55 HRC or 270.000 Psi. Some numbers i found on the net for the 2 HS alloys only gave me 60000 Psi They just don't compare.
4340
C 0.38-0.43
Mn 0.65-0.85
Si 0.2-0.35
P 0.0-0.04
CR 0.7-0.9
Ni 1.54-2.0
M 0.2-0.3
Fe Balance
This powder forging process does explain why Briggs and Stratton engines break con rods so easy.

That has to be my geeky post for the year.

Mik

[jpayne]

Thanks guys, it would appear you get what you pay for.
The set of rods in question are chinese G13B suzuki swift gti rods. another forum is trying to get a minimum order of 50 at $200 per set landed and delivered. It would appear the powder forging process is used to minimise cost as final machining need is reduced utilising this process as it is supposed to create blanks with high dimensional accuracy. but as you point out they can lack the strength of other alternate forging systems. Many OEM rods and other copmponents are manufactured this way but Im sure are engineered by engineers not copied.
While they are cheap they are unecessary for me so I might pass. Might leave me enough cash to...I dont know put a super flash machined alloy dash in the car

JP