stainless vs 4140 for headbolts with aluminum threads
stainless vs 4140 for headbolts with aluminum threads
(OP)
We only use 25lb/ft on 3/8" x 24 x 4" headbolt bolting aluminum heads onto aluminum cylinders. I am looking to keep compressive strength (torque on the copper headgasket) as close to constant as I can. With this being an air cooled engine. There are load of heating and cooling cycles. I'm looking at 303 stainless since the torque is so low but have been told that 4140 is closer to aluminum in its expansion! Aluminum is much prettier though!
Any comments or advise will certainly be appreciated
Marino
Any comments or advise will certainly be appreciated
Marino





RE: stainless vs 4140 for headbolts with aluminum threads
RE: stainless vs 4140 for headbolts with aluminum threads
RE: stainless vs 4140 for headbolts with aluminum threads
What is the reason you would not use the 303!
Marino
RE: stainless vs 4140 for headbolts with aluminum threads
RE: stainless vs 4140 for headbolts with aluminum threads
302/304/316 and 410 have a lot less and are fine. For REAL critical/fatigue applications such as steam turbine blades there is an extra low S mod. of 410, called 403.
Correctly tightened cyl. head bolts don't see much cyclic loading, but I'd use something else.