A286: An Economic Alternative to Inconel 718

Q: I need a 12 point bolt for a vacuum application with low off-gassing, min yield of 120 ksi, low magnetic permeability and minimum operating temps of 400C / 750F. Is Inconel 718 a good choice?

A: An Inconel 718 bolt will certainly work. The only other material you may want to consider would be an A286 in the cold worked version which will get you a min Tensile of 160ksi and a min yield of 120ksi. A286 bolts are readily available in a Socket Head Cap Screw design (if lead time is important) but if you need a 12 Point it could be made that way. Same is true for Inconel 718.

For more information on A286 see the link: https://www.extreme-bolt.com/a-286-fasteners-flanges.html

A286 Bolts for Diesel Engine Exhaust Stream

Q: Looking for bolts that will be used for large Diesel engine exhaust compensators in a power plant. The normal operating temp of the exhaust is 700 degrees F at full load. Loads do fluctuate often and engines experience downtime. The exhaust system does experience extreme force and vibration. Any suggestions?

A: It sounds like a safe bet would be A286 bolts. This material is geared for high temperature exhaust streams and will do well in this kind of environment. A286 is an age hardened material that can retain its strength to 1300°F. They also offer oxidation resistance to 1500°F . A286 fasteners offer 130ksi UTS and of 85ksi yield strength.

Age Hardened 17-4PH and A286 Bolts: Strength & Ductility

Q:

An application with limited space using a #4-40 screw with an assumed tensile strength of 120,000 PSI. This screw continues to break. Do you offer a screw with a higher strength? Also, This screw is used to hold a plate to the end of an air cylinder. It probably jars the fastener on every stroke and has about 6-8 strokes per minute.

A:

Regarding materials, there is a whole range of materials stronger than 120 ksi UTS however it sounds like you not only need strength but also a material that is ductile. I would suggest looking at fasteners made from the age hardened stainless steels such as A286 or 17-4 PH. Known for its high temperature oxidation resistance, A286 bolts also offer excellent high strength capabilities. A286 typically offers a min of 130ksi UTS and 85 yield. 17-4 PH bolting offers varies levels of strength depending on the age hardening process used ranging from 145ksi to 200ksi UTS (H1150 and H900 respectively). Given your application has a repetitive jarring motion you should look at the 17-4 H1150 or the A286 per ASTM A453, 660 A, B or C. These heat treat conditions will give you much more strength but also leave you with a material that is ductile and not brittle which may be a big factor in your fastener application.

High Temperature A-286 Fasteners vs Molybdenum fasteners

Q: I need some high temperature engine components that can provide high strength (100ksi yield) to 1000F as well as oxidation resistance? Are molybdenum bolts good for that?

A: Though Molybdenum is excellent in high temperature environments its generally reserved for very high temperature vacuum application where no oxygen is present. In addition your on the edge of molybdenum strength range. A better material choice would be A-286 fasteners. They are actually made for high temperature oxidation resistance and offer about 111ksi in yield strength which is in your range. They also maintain most of their strength to 1000F and could go to 1300F which will provide you the high temperature fastener you need as well.