0Cr13Ni8Mo2Al (PH13–8Mo) process performance

A. Introduction

PH13–8Mo is a precipitation hardenable stainless steel developed by Carpenter Technology Corporation. It is also known as AISI 13–8Mo. This alloy has excellent corrosion resistance, ductility, toughness and strength. The alloy has better corrosion resistance to H2S than other precipitation hardenable grades of steel like 17-4PH and 15-5PH. It is also weldable and has improved formability. Heat Treatments are used to maintain the mechanical properties and obtain maximum strength at high temperatures.

B. Mechanical Properties

PH13–8Mo has good mechanical properties. The mechanical properties of PH13–8Mo depends on the heat treatment and alloying element used. The following mechanical properties are observed after heat treatment of the alloy.

Tensile Strength: The tensile strength of PH13–8Mo is usually in the range of 1300 to 1450 MPa (188,580 to 211,720 psi).

Yield Strength: The yield strength of PH13–8Mo is usually in the range of 1100 to 1280 MPa (159,000 to 185,400 psi).

Elongation: The elongation of PH13–8Mo is usually in the range of 10 to 15 %.

Hardness: The hardness of PH13–8Mo is usually in the range of 38 to 50 HRC.

C. Heat Treatments

Heat treatment is an important process for PH13–8Mo to obtain the desired mechanical properties. Heat treatments are also used to maintain the mechanical properties at high temperatures. The following heat treatments can be used for PH13–8Mo:

Solution Annealing: Solution annealing is the process of heating the alloy in an inert atmosphere. This process is done to homogenize the alloy and obtain optimum mechanical properties. The solution annealing temperature for PH13–8Mo is usually in the range of 1090 to 1160°C (2000 to 2110°F).

Age-Hardening: Age-hardening is the process of heating and cooling the alloy at specific temperature and time to obtain the desired mechanical properties. The age-hardening temperature for PH13–8Mo is usually in the range of 464 to 593°C (870 to 1100°F).

D. Corrosion Resistance

PH13–8Mo has good corrosion resistance in both reducing and oxidizing environment. The alloy has excellent corrosion resistance to reducing acid, chloride and salt environments. It is also resistant to most gases and liquid chemicals. The alloy also has good resistance to intergranular corrosion.

E. Weldability

PH13–8Mo can be easily welded using any common welding process. It is recommended to use a filler material like 309L or 309L/ER309L for welding. Proper weld preparation and post-weld heat treatments are also recommended for better weldments.

F. Applications

PH13–8Mo can be used in a wide range of applications due to its good mechanical properties and corrosion resistance. Some suitable applications for the alloy are:

• Aircraft Components

• Nuclear Components

• Oil and Gas Exploration Equipment

• Chemical and Petrochemical Processing Equipment

• Food Processing Equipment

• Marine Components

• Valve and Pump Components

G. Conclusion

PH13–8Mo is a precipitation-hardenable stainless steel with excellent corrosion resistance, ductility and strength. The alloy has good resistance to H2S and weldable. Heat treatments are used to obtain the desired mechanical properties. This alloy is suitable for many applications due to its good mechanical properties and corrosion resistance.

13–8 Mo (UNS S13800) is a ferritic modified alloy of Type 409 stainless steel. This makes it suitable for a wide variety of applications. It is used in seawater equipment, chemical processing, and in power plants.

The alloy has good high-temperature strength and resistance to stress corrosion cracking. It also possesses good thermal fatigue and steady-state oxidation strength. Much like Type 409 stainless steel, 13–8 Mo has superior saltwater corrosion resistance in comparison to other stainless steels. 13–8 Mo is known for its good oxidation resistance up to 1500°F (816°C).

13–8 Mo is considered a good general purpose ferritic stainless steel for use in high-temperature applications such as those found in aircraft and power plants. It offers superior resistance to stress corrosion cracking and pitting, as well as good weldability and formability.

13–8 Mo is capable of being annealed in order to improve its machinability. This can be done by annealing at temperatures between 1050 and 1150°F (566 and 621°C). It is recommended that air cooling be used directly following annealing.

13–8 Mo contains a higher concentration of chromium and nickel, as compared to Type 409 stainless steel. This helps to give it superior resistance to a wide range of acids, including nitric and phosphoric acid. It also has good resistance to neutral and alkaline salts, such as chloride.

13–8 Mo is not a precipitation-hardenable alloy; however, it does maintain good strength even at high temperatures. It has a minimum tensile strength of 65 ksi (448 MPa), and a minimum yield strength of 40 ksi (276 MPa). It can open up to 10% in the annealed state.