0Cr15Ni7Mo2Al (PH15–7Mo) chemical composition

Introduction

15-7 Mo (PH 15-7 Mo or Alloy A-286) is an austenitic precipitation-hardening stainless steel alloy. It is an age-hardenable alloy designed for excellent strength, high temperature stability and general corrosion resistance. It is a non-magnetic alloy that is used in many areas such as aerospace, turbo-machinery, marine industries and nuclear industries. The chemical composition of 15-7 Mo is as follows: Iron (Fe) - 65 to 70%, Chromium (Cr) - 15.0 - 17.0%, Nickel (Ni) - 7.0 - 9.0%, Manganese (Mn) - 0.5 - 1.5%, Silicon (Si) - 0.5 - 1.0%, Aluminum (Al) - 2.5 - 3.5%, Other elements such as molybdenum (Mo), titanium (Ti), Copper (Cu), phosphorus (P) and sulfur (S) can also be present in 15-7 Mo in trace amounts.

Properties

15-7 Mo has excellent mechanical properties, good resistance to temperatures up to 950 °F (510 °C) and good corrosion resistance in both as-welded and as-formed conditions. This alloy has very good creep resistance and low magnetic permeability. 15-7 Mo also has excellent fatigue properties and high resistance to stress corrosion cracking. Additionally, 15-7 Mo has excellent tarnish-resistance, even under high-temperature mechanical and chemical exposures.

Applications

15-7 Mo is mainly used in products that require high strength and temperature resistance such as jet engines, nuclear and industrial applications including balls, injectors, tubing and fuel systems. It is also used for electronic and medical parts, springs, cryogenic instrumentation, turbine blades and blisks, as well as industrial fasteners.

Conclusion

15-7 Mo (PH 15–7Mo or Alloy A-286) is a precipitation-hardening austenitic stainless steel alloy, primarily used in high-temperature applications such as jet engines, nuclear and industrial applications. It is a non-magnetic alloy with excellent mechanical properties and resistance to temperatures up to 950 °F (510 °C). 15-7 Mo also has excellent corrosion, fatigue and stress corrosion cracking resistance, as well as high tarnish-resistance. It is primarily used in products that require high strength and temperature resistance.

UNS S31260 (PH15-7Mo) is a precipitation-hardenable martensitic stainless steel. It combines high strength, hot and cold workability and corrosion resistance.

PH15-7Mo is an austenitic-bearing steel with its carbon content slightly lowered to 0.16% to make the alloy more weldable. It can be strengthened by heat treatment and has slightly higher corrosion resistance than the standard PH17-4 alloy. The addition of 7% molybdenum and 0.9% phosphorus gives the alloy an enhanced level of corrosion resistance as compared to stainless steels containing 18% chromium and 8% nickel.

The alloy is used in wet and corrosive environments, and is often specified for pump shafts, paper mill equipment, chemical plant machinery and other harsh duty applications where some additional toughness and resistance to stress corrosion are desired. Due to its combination of mechanical properties, high strength and resistance to stress corrosion cracking, PH15-7Mo is also specified for applications in the aircraft and aerospace industries.

PH15-7Mo has excellent hot workability due to its lower carbon content, good formability and ease of fabrication. Weldability is excellent, both arc and gas welding are used. Machinability is good and superior to many stainless steels, although the high molybdenum content causes cutting tools to wear at a slightly greater rate.

It has a black finish that can be produced with standard heat treatment and keeps its corrosion resistance as it ages in seawater. This makes it a great steel for seawater applications. PH15-7Mo does not respond to hardening by full-time heat process and require a pre-treatment in order to reach maximum hardness.