7075 Vs Steel

I've machined 7075 before using speed and feed calculations on one of the CNC mills, and it machined just great.

The other day I machined some 7075 manually on the lathe to make some mold inserts (for quick ship it was actually cheaper than other options in the size I needed).

Dang its tough stuff. I had to look it up again. Its stronger than some steel alloys, and it machines like it. Bob La Londe

-------------------- It's also brittle and notch sensitive. The poles of my tent, designed by a former aeronautical engineer, are 7001 which is relatively less brittle. Bungeeing it to a motorcycle was enough to crack one at the end.

My tent is polyester fabric which is slightly less strong but much more UV resistant. While I was there a user phoned from the top of Mt Washington to report his tent was doing fine in a 135 MPH wind. Jack has designed for Mach

2. The original catalog reveals their "natural" California origin, among other things. Warning - prudes may be offended, but that's just how they are, get used to it.

   formatting link
   Some considerably more liberal Mensa friends thought I would fit their uptight stereotype of the Right until I took them to visit the Stephensons to ask about their island tent-cabin rental and we shared a hot tub with Jack's gorgeous wife Joan. My eyes, my eyes!

It also rings like hardened steel, and so is what movie prop sword blades are made of.

Joe

I offer one mold with either stainless inserts or at a lesser price aluminum inserts. Usually 6061-t6 aluminum. Its less about material cost than machining difficulty. I was out of the right size 6061, so I priced small quantities from different vendors for quick shipment. The

After working with it, and determining its general toughness I may consider pricing it in multi rod quantities and discontinue stainless as an option. Its not as tough as 304, but its tougher than any mold steel I have worked with.

I was not aware of a brittleness property, but that may be a function of treatment. It is used for multiple firearms actions including for home builders in the rather brutal 1911 series. Of course it was the magic answer to toughness and corrosion resistance for the M16A1 in Vietnam over previous alloys.

MILD, not mold. Most mold steels are quite tough, and hard. The minimum is probably 4140HT, and most others for high production are much harder.

I was not aware of a brittleness property, but that may be a function of treatment. It is used for multiple firearms actions including for home builders in the rather brutal 1911 series. Of course it was the magic answer to toughness and corrosion resistance for the M16A1 in Vietnam over previous alloys. Bob La Londe

------------------------------------

I haven't found a clear and not highly technical reference on its properties for you. One showed fatigue life around 1000 cycles near yield strength, rapidly increasing below it. Another mentioned that sanding parallel to the stress with 150 grit paper was as effective as buffing to remove scratches that could initiate notch cracking. The M16 bolt locks into the barrel extension and doesn't stress the receiver. Likewise the 1911 barrel locks into grooves in the slide, not the frame.

The aerospace advice I heard was to look closely at its strengths and liabilities before designing with it.

Its true, the M16/AR15/M4 series of rifles is fairly gentle on the lower as are "most" gas impingement recoil systems since the whole of the operating recoil mechanism is in the upper *(not true gas, and not just direct impingement), but delayed blow back is still pretty hard on the structure. I wasn't saying 7075 could take repeated hammer blows over and over again, but that it could take a "lot" over and over again.

• the nature of the Armalite mechanism is sometimes debated.

My goal eventually for an aluminum 1911 frame is to run one with a GSG .22LR slide which changes things again. The GSG upper is basically direct blow back fully contained in the slide. Is there any hammering at the end of the stroke. Maybe, but not much force compared to the torquing of 45 ACP.