Higher tensile strength for alloy steel 4340 screw
Higher tensile strength for alloy steel 4340 screw
(OP)
May be someone can help me in this:
I have a screw :#10-32 (diameter .19", length 1")hex head, full thread, alloy steel (4340), that according to NAS1801 it has 160 KSI tensile strenght.
Can I heat treating it, to get 300 KSI tensile strenght, if the case what would be the treatments, temperatures and times.
thanks in advance
I have a screw :#10-32 (diameter .19", length 1")hex head, full thread, alloy steel (4340), that according to NAS1801 it has 160 KSI tensile strenght.
Can I heat treating it, to get 300 KSI tensile strenght, if the case what would be the treatments, temperatures and times.
thanks in advance





RE: Higher tensile strength for alloy steel 4340 screw
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RE: Higher tensile strength for alloy steel 4340 screw
I just want to know if this material can get better tensile strength and what are the steps in heat treating to get that.
thanks
RE: Higher tensile strength for alloy steel 4340 screw
austenitize at 800 °C
oil quench
temper at 225 °C
You must be careful with material in this condition. Low elongation, low fracture toughness, low impact resistance, and low resistance to hydrogen assisted cracking and stress corrosion cracking are all strong probabilities.
RE: Higher tensile strength for alloy steel 4340 screw
The screw will be use inside of the cockpit(airplane), for some attaching device.
can you be more specific about the process
austenitize at 800c but what time?
oil quench what Temperature of the oil?
temper how long?
Mater if the screw already has a treating process,
(as specs indicated)
do I need to do a previo process?
Thanks in advance!!
RE: Higher tensile strength for alloy steel 4340 screw
As CoryPad mentioned, this will result in a very brittle microstructure, with low fracture toughness. And since you will be eliminating the residual compressive stresses in the shank-to-head transition that were introduced by fillet rolling, this fastener will be very susceptible to SCC and fatigue failures in this area. Do you intend to have this part electroplated after heat treating? If the answer is yes, you will now have a very brittle fastener that has been exposed to hydrogen, and therefore hydrogen embrittlement and delayed fracture are a signficant concern.
Based on all of this information, you would be well advised to find a proper aerospace-quality fastener rather than re-work an existing part.
RE: Higher tensile strength for alloy steel 4340 screw