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ASTM A743 CA-6NM AISI CA6NM Grade Gr CA6NM forged forging steel guide vane wicket gates blades for francis hydro power turbine hydraulic water turbine generator from china
Wicket gate plays an important role in hydropower plants. Wicket gate increases turbine revolution and after paralleling with net, increases the turbine load. Changing in turning place of this part causes the change in flow rate of turbine runner. Wicket gate conducts the water flow into runner. In this case, the angle of entering water to runner is too important and plays an important role in efficiency and reducing cavitations.0005.jpg
Because of nature of flowing water in turbine direction, sandy parcels and impure material, and cavitations causes friction and corrosion in wicket gates. So after a time depend on the condition of operation and the water and grease material, the journal place and the sealing on the wicket will corrode.
In this case, manufacturing and and/or purchasing a new wicket gate is too expensive and needs much time, so AzarAb tries to use certain economical maintenance methods and makes the start to power plants easy.
Based on following applicable method wicket gates can be ready to perform in a short time: total wicket gate cleaning, quality control in all levels repairing the ruined parts, cleaning the welding surfaces, thermal operation for stress – relief, make the repaired surfaces to standard sizes by lathe operation, doing chrome campsite coating in friction surfaces and wicket gates seats.
The machining operation of wicket gate is too important in a way that shaft and seat angle of the sealing should be in the same direction.
F6NM is a low–carbon martensitic stainless steel with basic corrosion resistance, good strength, good toughness and much better weldability than most martensitic grades of stainless steel.
Approximate Composition – 13% Cr, 4.0% Ni, 0.5% Mo ≤ 0.05% C (EN and ASTM standards vary in chemical composition).
This grade combines the following characteristics:
- Basic pitting and crevice corrosion resistance
- Moderate sulphide stress cracking resistance
- Good yield strength (520 to 800 MPa minimum in EN standard depending on heat treatment)
- Better toughness than most martensitic grades (one of only 2 martensitic grades with guaranteed sub-zero impact toughness in EN pressure standards)
- Good weldability compared to other martensitic grades. Still requires pre- and post-weld heat treatment
F6NM is martensitic grade of stainless steel with several important enhancements. The molybdenum addition gives an improved corrosion resistance. The low carbon gives much improved weldability and along with the nickel produces excellent toughness. The dominant use of this grade is in the oil and gas industry.
Applications which illustrate these features include:
Valve bodies, flanges, valve seats, oil field equipment, hydro-electric turbine systems, pumps, chemical process plant, pressure die casting.
