B
Big Al
Guest
With these already hardened 41 series, is there any work hardening going on? What are they like after all the machining is completed? I know you sure get work hardening in the annealed state, from machining.
,,,,,,,,,,,,,,,,,,I just need to clear something up. Earlier i stated that 709M is similar to 4340. It is indeed classified as a 4140 and has often been called free machining 4140. The reason it is also often refered to as 4340 is because its actual tensile strength is almost identical to that of 4340. The machine and cutting speeds in lathes or CNCs can be in creased by 33%. Tooling lasts longer and the surface finish is like that of a stainless steel of good qulity.
No steel can contain 85,000 psi when there is a large volume of gas working on a large surface area.
The strongest part of an action needs to be and has to be the case head. In my mind an action should be designed to support and control the barrel first and foremost. Action strength quotes are more for peace of mind.
Tony Z.
,,,,,,,,,,,,,,,,,,I did some ringing arround today to all of the majior steel suppliers..
The guy i spoke to was well known to my boss as being very knowledgable but had never heard of thyssen 6580 or 6582.
As for the heat treatment i phoned a heat treatment mob in west Brisbane and they will heat treat EN26 to any hardness i specify. They hardness test after heat treatment and could supply test certs and garentee a propper job.
In saying that if i design a beefy action from EN26 at say 40 HRC and have the bolt treated to 44 HRC this will still give good machinability in as hardened state and help prevent galling and should be MORE than strong enough for my choice of calibre, .308W at the biggest.
Finial opinions?
Cheers
Leeroy
,,,,,,,,,,,,,,,,,,,,,,Peter, if you think i should keep to less than 42 HRC then thats what i'll do.
I would like to get at least 3-4 points difference in Hardness between bolt and receiver so will probably go for 39 HRC for the receiver and 43 HRC for the bolt. Or should i go the other way arround and make the action harder?
Either way I think thats a pretty good compromise..
.
Cheers
Leeroy