Stainless steel product, use of the product and method of its manufacture

Abstract

The invention relates to a stainless steel product, particularly to a duplex stainless steel casting with high machinability, to the use of the product and to the method to produce the product. The product contains in weight percent up to 0.07% carbon, up to 2% silicon, 3-8% manganese, 19-23% chromium, 0.5-1.7% nickel, up to 1% of molybdenum and/or tungsten with the formula (Mo+½W) less than 1%, up to 1% copper and 0.15-0.30% nitrogen, the remainder being iron and incidental impurities.

1 - 18 . (canceled) 
     
     
         19 . A duplex stainless steel casting with high machinability, wherein the microstructure of the casting contains 30-70 vol percent ferrite and 30-70 vol percent austenite and the casting contains in weight percent: up to 0.07% carbon, up to 2% silicon, 3-8% manganese, 19-23% chromium, 0.5-1.7% nickel, up to 1% of molybdenum and/or tungsten with the formula (Mo+½W) less than 1%, up to 1% copper and 0.15-0.30% nitrogen, the remainder being iron and incidental impurities. 
     
     
         20 . The duplex stainless steel casting of  claim 19 , wherein it contains up to 0.05% carbon. 
     
     
         21 . The duplex stainless steel casting of  claim 20 , wherein it contains up to 0.03% carbon. 
     
     
         22 . The duplex stainless steel casting of  claims 19 , wherein it contains 4-6% manganese. 
     
     
         23 . The duplex stainless steel casting of  claim 19 , wherein it contains 21-22% chromium. 
     
     
         24 . The duplex stainless steel casting of  claim 19 , wherein it contains 1.1-1.7% nickel. 
     
     
         25 . The duplex stainless steel casting of  claim 19 , wherein it contains 0.20-0.26% nitrogen. 
     
     
         26 . The use of the duplex stainless steel casting with high machinability of  claim 19  in pumps, valves or impellers. 
     
     
         27 . Method for producing the duplex stainless steel casting with high machinability of  claim 19 , wherein the casting is produced by centrifugal casting, chill casting, die casting, investment casting, pressure casting, permanent mould casting, sand casting or vacuum casting.