SRIF has conducted deep principal theoretical and practical research of electro-slag remelt casting (ESRC) technology. In the institute, the temperature field of special shape ESRC castings used for hydraulic power station has been investigated by computer simulation, and foundry technology of the ESRC castings has been developed. In recent years many important ESRC achievements have been made and SRIF has supplied over ten thousand tons of premium ESRC castings to large and medium hydraulic power stations at home and abroad, such as Three-gorge hydraulic power station. Now SRIF has 2 ESRC furnaces (capacities of 700 kVA and 3,000 kVA), by which ESRC castings of 0.1-20t/piece can be produced . The main ESRC products are guide vanes of hydraulic turbine, changing section plate blanks, connecting rods of air-compressor, bi-metal buck-teeth of excavator ,etc.

 ERC wicket gates for hydro-turbine

       ESC wicket gates for hydro-turbine are one of main products of the company, the technologies applied are of intelligent property right. So far, we have successfully supplied 1000 pieces over sound-castings to more than 20 power stations at home and abroad, and the quality of all these products have inspected up to the advance level in the world. The annual production capacity is more than2000 tons. The materials that have been used includeZG0Cr13Ni4Mo, ASTM CA-6NM, DIN G-X5CrNi13 4, ZG0Cr13Ni5Mo, ZG0Cr16Ni5Mo, ZG0Cr17Ni4Cu3Nb, ZG20SiMn etc. Wicket gate with max. weight of 20 tons can be produced.
The company also made a significant contribution to Three Gorges Power Station by supplying with a complete set integrate wicket gates for hydro-turbine, gross weight 13T, max. diameter 690mm, height 5600mm , being one of a few domestic manufacturers who owned independent intelligent property on their products supplied. All quality criteria of these wicket gates have been tested in full compliance with VGS technical specification requirements.

Wicket gates for medium-small power station

Hydro-turbine wicket gate for Three Gorges Power Station, gross weight 13T, height 5600mm

Other Castings by ESC
       The company has also adopted ESC technology to manufacture some other important castings besides, such as slab-blade for hydro-turbine, the rotating for air compressor, the die mould, crankshaft, round Rotating drum for medicine-made machine ingots in a wide range sizes etc..

drum for medicine-made machine, connecting-rod

Connecting rods for air compressor

Slab-blades for hydro-turbine

Upper and lower trunnions of hydro-turbine wicket gate for Three Gorges Power Station

The main advantages of ESC products
1. During ESC, the sulphur and impurities are separated from castings, resulting in better toughness, fatigue strength and weldability.
2. NDT meets the requirements of class I of CCH70-3 and ASTM A 609 .
3. Cavitations damage resistance is increased by 30 percent as compares with that of sand castings.
4. Machining allowance is small.
5. ESC is a metal mould process, and environmental pollution is less.

CAD expert system of ESC wicket gate design
       Consumable electrode, crucible (mould) etc. of ESC wicket gate are designed using a CAD expert system. This system constructed by establishing geometrical model of wicket gate, geometrical model and mathematical model of crucible (mould), reduces the risk of errors to a minimum and gives a fast lead-time.

ESC process simulation
       ESC 3D computer simulation is a very effective means checking ESC process. It may reduce energy consumption and dispensable waste , shortening manufacturing time of castings.

Temperature-field of ESC wicket gate for hydro-turbine at different time

About ESC
       ERC is a process which finishes the two programmes of electroslag remelting refining and casting in sometimes, so that castingsproduced have not only good internal quality, but also long service life.

Schematic diagram of ESC fundamental

   

Control room of ESRC Furnace

ESRC connecting rods of air-compressor

   

ESRC Process

  

 
3000kVA ESRC furnace
   

   
 
 Control room of ESRC Furnace

The principle of ESRC

        ESRC process comp;etes electroslag remelting refining and casting in the same time, so the castings produced by ESRC have not only good inner quality, but also good material property. AT the beginning of ESRC process a poor of molten slag with a depth of 100-200mm is formed at the bottom of a crucible. When the consumable alectrode connected with power sourceis submerged into the molten slag, strong electric current passes through the slag pool exceeds the melting point of the the consumable electrets from the end of the electrode falls through the slag pool by gravity. In this process, the harmful elements and the impurities in the consumable electrode by gravity. In this process ,the harmful elements and the impurities in the consumable electrode are lowered, the molten steel is refined. The molten droplets through the slag pool form a metal pool under the slag pool, the metal is gradually solidified by strong circulated cooling water,and at last form a casting. In ESRC process, the melting of the consumable electrode, the filling and the crucible is full filled, and thus a casting is being made from the bottom to the top of the crucible gradually.