Why is FV520b used as the material for centrifugal compressor impellers?

The FV520B is a new type of martensitic precipitation-hardening stainless steel resistant to acids and heat, developed on the basis of the original FV520. This steel grade achieves maximum strengthening through the combined effect of strengthening elements such as Cu, Nb, and Mo, which result in the precipitation of ε-Cu, NbC, Mo2C, M7C3, and M23C6 during the aging process. The FV520B exhibits good wear resistance, corrosion resistance, and weldability. It hardens upon low-temperature heat treatment, and it has stronger resistance to intergranular corrosion and pitting corrosion than 17-4PH; its corrosion resistance is comparable to that of 304. It is commonly used in industrial and marine environments where a low rust rate is required.

The impeller is the main component through which the compressor performs work; it operates at very high rotational speeds (2000 m/s to 10,000 m/s or even higher). Due to the presence of solid particles in the compressed medium – most of which are particles with a size of 5–10 μm – these particles can be carried by the high-speed airflow and cause erosion and wear on the impeller at a certain speed and angle； As long as there is a slight amount of material erosion on the leading edge of the compressor impeller, a gap of 0.05 mm can cause local stall. Continued erosion leads to thinning of the impeller, disrupts the dynamic balance of the rotor, results in vibration in the compressor, and may even lead to accidents. ——For the above reasons, choosing FV520B as the material for centrifugal compressor impellers allows this type of erosion wear to be mitigated effectively, which is also the main reason why FV520B is widely selected as the material for high-speed centrifugal compressor impellers in the industry.

Utilize its high strength to accommodate the high rotational speeds of centrifuges~~

Thank you. Is it just for wear resistance? Does it also provide protection against hydrogen embrittlement, which is caused by hydrogen attack? If it’s only for wear resistance, can other high-strength materials be used, such as HG785?

I think the original poster has a misunderstanding; I was merely emphasizing that the FV520b boasts good erosion resistance at high rotational speeds (the FV520B martensitic stainless steel features high strength, high toughness, high wear resistance, and high corrosion resistance). The welding performance is also very good)! HG785 is primarily used in boiler drums, bellows, etc. Due to limitations in its performance, it cannot currently be applied to the impellers of high-speed centrifugal compressors ； Some fan impellers may use this material!

Thank you for your reply; it seems like you’re an expert! Why can’t HG785 be applied to high-speed centrifuge impellers? Or what are the special requirements for the impeller material?