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MATERIAL SPECIFICATIONS
Selecting the optimum
material for use in a given application is of paramount importance. Thats why ARP
manufactures fasteners from a wide assortment of materials
ranging from popular
stainless steel and 8740 chrome moly to exotic alloys that have been developed to handle
space travel. You should also know that there are grades within specific alloys. For
example, 8740 is available in four grades: 1. SDF (guaranteed seamless and defect free). 2
CHQ (cold head quality). 3. Aircraft. 4. Commercial. ARP uses only the first two (SDF and
CHQ), even though they cost more than double Aircraft quality. These are the
important features that set ARP squarely at the forefront of the industry. Each and every
fastener that carries the ARP name is made from the best possible material for the
application, carefully heat-treated in-house, and machined to perfection.
STAINLESS STEEL: Ideally suited for many automotive and marine applications
because stainless is tolerant of heat and virtually impervious to rust and corrosion. ARP
Stainless 300 is specially alloyed for extra durability. Its polished
using a proprietary process to produce a beautiful finish. Tensile strength is typically
rated at 170,000 psi.
8740 CHROME MOLY: Until the development of todays modern alloys chrome
moly was popularly considered a high strength material. Now viewed as only moderate
strength, 8740 chrome moly is seen as a good tough steel, with adequate fatigue properties
for most racing applications, but only if the threads are rolled after heat treatment, as
is the standard ARP production practice. Typically chrome moly is classified as a quench
and temper steel, that can be heat treated to deliver tensile strengths between 180,000
and 210,000 psi.
ARP2000: An exclusive, hybrid-alloy developed to deliver superior
strength and better fatigue properties. While 8740 and ARP2000 share similar
characteristicsARP2000 is capable of achieving clamp loads in the 215,000-220,000
psi range. ARP2000 is used widely in short track and drag racing as an up-grade from 8740
chrome moly in both steel and aluminum rods. Stress corrosion and hydrogen embrittlement
are typically not a problem, providing care is taken during installation.
L19: This is a premium steel that is processed to deliver
superior strength and fatigue properties. L19 is a very high strength material compared to
8740 and ARP2000 and is capable of delivering clamp loads in the 230,000-260,000 psi
range. It is primarily used in short track and drag racing applications where inertia
loads exceed the clamping capability of ARP2000. Like most high strength, quench and
temper steelsL19 requires special care during manufacturing to avoid hydrogen
embrittlement. This material is easily contaminated and subject to stress corrosion. It
must be kept well-oiled and not exposed to moisture.
AERMET 100: With a typical tensile strength of 280,000 psi, Aermet 100 is
a new martensitic super-alloy that is stronger and less expensive than the super-alloy
austenitic materials that follow. Because it is capable of achieving incredibly high
clamping loads, it is ideal for short but extreme environments like top fuel, funny car
and some short track applications. Although Aermet 100 is a maraging steel that is far
superior to other high strength steels in its resistance to stress corrosion, it must be
kept well-oiled and not exposed to moisture.
INCONEL 718: A nickel based material that is in the high
temperature, super-alloy class, it is found to be equally suitable in lower temperature
applications. This material delivers tensile strengths into the 220,000 psi range and
exhibits improved fatigue properties. Best of all, Inconel 718 is completely immune to
hydrogen embrittlement and corrosion.
ARP3.5 (AMS5844): While similar to Inconel 718, these super-alloys
are found in many jet engine and aerospace applications where heat and stress attack the
life of critical components. The high cobalt content of this alloy, while expensive,
delivers a material with superior fatigue characteristics and typically tensile strength
in the 270,000 psi range. The immunity to hydrogen embrittlement and corrosion of these
materials is a significant design consideration. These materials are primarily used in
connecting rods where extremely high loads, high RPM and endurance are important
factorsFormula 1, Winston Cup and CART applications.
CUSTOM AGE 625+: This newly formulated super-alloy demonstrates superior
fatigue cycle life, tensile strength and toughnesswith complete resistance to
atmospheric corrosion and oxidation. ARP is the first to develop manufacturing and testing
processes for fasteners with Custom Age 625+. Best of all it is less expensive and
expected to soon replace MP-35 as the material of choice in the high strength, super-alloy
field. Typical tensile strength is 260,000 psi.
QUICK REFERENCE GUIDE TO MATERIALS USED IN
FASTENERS |
Material |
Use? |
Yield Strength |
Tensile
Strength |
Used For |
Grade 5 |
No |
90,000 psi |
120,000 psi |
Accessory bolts and studs |
Grade 8 |
No |
120,000 psi |
150,000 psi |
Accessory bolts
and studs |
"Stainless 300" |
Yes |
140,000 psi |
170,000 psi |
Accesory bolts and studs, head studs |
ARP Custom 450 |
Yes |
150,000 psi |
180,000 psi |
Head bolts,
accessory bolts |
8740 chrome moly |
Yes |
160,000 psi |
190,000 psi |
Rod bolts, head and main studs and bolts |
A286 |
Yes |
170,000 psi |
200,000 psi |
Head bolts,
connecting rod bolts |
ARP2000 |
Yes |
180,000 psi |
215,000-220,000 psi |
Connecting rod bolts |
L19 |
Yes |
200,000-230,00
psi |
230,000-260,000
psi |
Connecting rod
bolts |
Inconel 718 |
Yes |
190,000-210,000 psi |
220,000-240,000 psi |
Connecting rod bolts |
Custom Age 625+ |
Yes |
235,000-255,000
psi |
250,000-280,000
psi |
Head studs,
connecting rod bolts |
ARP 3.5 |
Yes |
220,000-250,000 psi |
250,000-280,000 psi |
Connecting rod bolts |
Aermet 100 |
Yes |
258,000 psi |
300,000 psi |
Connecting rod
bolts |
SPECIAL NOTE: The U.S. Government has recently implemented new guidelines
relating to rating fastener strength. Unless a specific fastener has been tested in a
government approved independent lab, manufacturers are enjoined from using a specific
rating. Even though, in the case of ARP, the very same equipment and testing procedures
are used in-house. Rather than have expensive duplicate tests run on literally hundreds of
part numbers. Which would drive the cost of each fastener through the roof, ARP is
following approved guidelines by using generalities to describe strength ratings. Please
remember that ARP is one of the few firms in the world licensed by the U.S. Government to
manufacture MS21250 fatigue rated fasteners and is QPL (Qualified Products Listed). There
are few fastener manufacturers in the world with ARPÕs proven reputation for producing
quality products.
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