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Machining Heat-Resistant Super Alloy(HRSA) with YG-1 – Material

31 May 2022

Information provided by
Global Industry Project Manager - Aerospace, Power Generation and Medical

 

Heat-Resistant Super Alloy (HRSA) is a group of important materials used in the hottest parts of jet and rocket engines where temperatures can reach as high as 1400 °C. It has become an irreplaceable key material for hot-end components in aviation engines. As a percentage usage accounts for 40% to 60% of the total material usage per engine.

HRSA materials are divided into three subgroups based on nickel, cobalt, and iron with additional specific alloying elements added to increase chemical stability, strength, toughness, and durability at high temperatures.

These metals have excellent heat resistance and maintain strength, toughness, and dimensional stability at extreme temperatures significantly higher than those aerospace structural materials must withstand. HRSA is used for critical engine parts such as high-pressure turbine blades, discs, combustion chambers, afterburners, and reverse thrusters. HRSA is also widely used in the medical and energy fields due to its excellent corrosion resistance, high strength and overall performance.

Heat Resistant Super Alloy can be classified into three groups.

1. Ni-Based Super Alloy

Ni-Based Super Alloy is the most widely used HRSA subgroup. Its main feature is its outstanding strength over a wide temperature range combined with good corrosion resistance. It is primarily used in aircraft jet engine parts and in the oil and gas industry. The hardness of the material ranges from 5 to 44 HRc, but the hardness of the most commonly used materials is 32 to 42 HRc. Some popular materials are Inconel 718, Inconel 625, and Waspaloy.

2. Iron-Based Super Alloy

Iron-Based Super Alloy can be an alternative to Ni-Based Super Alloy because of its economical advantages. They offer similar benefits, but Iron-Based Super Alloy comes at a lower price. This alloy is a material developed from austenitic stainless steel and has a very low thermal expansion effect. Because it has the lowest elevated thermal strength among HRSA, it is mainly used for components requiring heat resistance to creep, oxidation, corrosion and wear within the lower thermal expansion. (Shaft, Casing, Ring, etc.) The most commonly used material in this group is A-286, which has a hardness of about 25 HRc.

3. Cobalt-Based Super Alloy

Cobalt-Based Super Alloy has excellent wear resistance and chemical stability under difficult conditions. Therefore, it is mainly used in valves and fittings in acidic environments and medical implants such as artificial hip joints. It is the most difficult to machine HRSA subgroup, producing very high wear on the cutting edge. The most popular materials are Stellite 6 & 21 with a hardness of 32-36 HRc.

 

In the next episode, we will continue with the content of the machining solution of Heat-Resistant Super Alloy(HRSA).