Cast Iron With Improved High Temperature Properties

Abstract

A nodular, compacted graphite or other hybrid or duplex graphite morphology cast high silicon iron is disclosed which contains up to 1.5% tungsten, up to 0.8% vanadium, and up to 1.2% niobium; and at least 60.0% iron, all percentages are based on the total weight of the composition. This cast iron exhibits high strength and good ductility over a wide temperature range compared to the conventional SiMo ductile iron. The compositions may further contain, up to 1.5% molybdenum and up to 1.0% chromium to offer improvements in material strength. The compositions may include 0.2 to 0.5% by weight aluminum and up to 1.2% chromium for further oxidation resistance and 0.5 to 5.0% nickel for corrosion resistance.

1 . A high silicon cast iron composition comprising:
 greater than about 60 wt. % iron;   between about 2.8 to about 5.0 wt. % silicon;   from about 0.03 to about 1.5 wt. % tungsten;   up to about 0.8 wt. % vanadium; and   up to about 1.2% niobium.   
     
     
         2 . The cast iron composition of  claim 1 , further comprising at least one constituent selected from the group consisting of molybdenum, chromium, nickel and carbon. 
     
     
         3 . The cast iron composition of  claim 1 , wherein said vanadium is present in an amount of between about 0.02 to about 0.8 wt. %. 
     
     
         4 . The cast iron composition of  claim 1  wherein said niobium is present in an amount of between about 0.02 to about 1.2 wt. %. 
     
     
         5 . The cast iron composition of  claim 2  wherein said molybdenum is present in an amount up to about 1.5 wt. %. 
     
     
         6 . The cast iron composition of  claim 2  wherein said aluminum is present in an amount of between about 0.2 and 3.0 wt. %. 
     
     
         7 . The cast iron composition of  claim 2  wherein said nickel is present in an amount of between 0.5% and about 5.0 wt. %. 
     
     
         8 . The cast iron composition of  claim 2  wherein carbon is present in an amount such that the wt. % carbon plus ⅓ the wt. % silicon is up to about 4.9 wt. %. 
     
     
         9 . Products formed from the cast iron composition of  claim 1 . 
     
     
         10 . A molded article comprising a nodular, compacted graphite or hybrid or duplex graphite having a cast iron composition, wherein the cast iron composition comprises:
 greater than about 80 wt. % iron;   between about 2.8 to about 5.0 wt. % silicon;   from about 0.03 to about 1.5 wt. % tungsten;   from about 0.2 to about 1.2 wt. % niobium; and   up to about 0.8 wt. % vanadium.   
     
     
         11 . The molded article of  claim 10  wherein said vanadium is present in an amount of between about 0.02 to about 0.8 wt. %. 
     
     
         12 . The molded article of  claim 11  further comprising between about 0.2 to about 1.5 wt. % molybdenum. 
     
     
         13 . The molded article of  claim 11  further comprising between about 0.2 to about 3.0 wt. % aluminum. 
     
     
         14 . The molded article of  claim 11  further comprising between about 0.5 to about 5.0 wt. % nickel. 
     
     
         15 . The molded article of  claim 11  wherein carbon is present in an amount such that the wt. % carbon plus ⅓ the wt. % silicon is up to about 4.9 wt. %. 
     
     
         16 . The molded article of  claim 10  wherein the article is an exhaust manifold. 
     
     
         17 . The molded article of  claim 10  wherein the article is a turbocharger component. 
     
     
         18 . The molded article of  claim 10  wherein the article is a catalytic converter housing. 
     
     
         19 . The molded article of  claim 10  wherein the article is a fuel cell component. 
     
     
         20 . A high silicon cast iron composition comprising:
 At least 60 wt. % iron;   between about 2.8 to about 5.0 wt. % silicon;   from about 0.2 to about 1.2 wt. % niobium;   up to about 1.5 wt. % tungsten;   up to about 0.8% vanadium; and.   at least one constituent selected from the group consisting of molybdenum, aluminum, nickel and carbon.   
     
     
         21 . The cast iron composition of  claim 20 , wherein said vanadium is present in an amount of between about 0.02 to about 0.8 wt. %. 
     
     
         22 . The cast iron composition of  claim 20  wherein said molybdenum is present in an amount up to about 1.5 wt. %. 
     
     
         23 . The cast iron composition of  claim 20  wherein said tungsten is present in an amount of between about 0.003 to about 1.5 wt. %. 
     
     
         24 . The cast iron composition of  claim 20  wherein said nickel is present in an amount of between 0.5% and about 5.0 wt. %. 
     
     
         25 . The cast iron composition of  claim 20  wherein carbon is present in an amount such that the wt. % carbon plus ⅓ the wt. % silicon is up to about 4.9 wt. %.