STABILIZED ACID AND ALKALI RESISTANT Ni-Cr-Mo-Co ALLOYS

Abstract

A nickel-chromium-molybdenum-copper alloy resistant to 70% sulfuric acid at 93° C. and 50% sodium hydroxide at 121° C. for acid and alkali neutralization in the field of waste management; the alloy contains, in weight percent, 27 to 33 chromium, 4.9 to 7.8 molybdenum, greater than 3.1 but no more than 6.0 copper, up to 3.0 iron, 0.3 to 1.0 manganese, 0.1 to 0.5 aluminum, 0.1 to 0.8 silicon, 0.01 to 0.11 carbon, up to 0.13 nitrogen, up to 0.05 magnesium, up to 0.05 rare earth elements, with a balance of nickel and impurities. Titanium or another MC carbide former can be added to enhance thermal stability of the alloy.

What is claimed is: 
     
         1 . A nickel-chromium-molybdenum-copper alloy resistant to 70% sulfuric acid at 93° C. and 50% sodium hydroxide at 121° C., consisting essentially of:
 27 to 33 wt. % chromium 
 4.9 to 7.8 wt. % molybdenum 
 greater than 3.1 wt. % but no more than 6.0 wt. % copper 
 up to 3.0 wt. % iron 
 0.3 to 1.0 wt. % manganese 
 0.1 to 0.5 wt. % aluminum 
 0.1 to 0.8 wt. % silicon 
 0.01 to 0.11 wt. % carbon 
 up to 0.13 wt. % nitrogen 
 up to 0.05 wt. % magnesium 
 up to 0.05 wt. % rare earth elements 
 up to 0.56 wt. % titanium 
 up to 1.12 wt. % niobium 
 up to 2.24 wt. % tantalum 
 up to 2.24 wt. % hafnium 
 with a balance of nickel and impurities. 
 
     
     
         2 . The nickel-chromium-molybdenum-copper alloy of  claim 1 , wherein the impurities comprise levels of at least one of cobalt, tungsten, sulfur, phosphorus, oxygen, and calcium. 
     
     
         3 . The nickel-chromium-molybdenum-copper alloy of  claim 1 , wherein the alloys are in wrought forms selected from the group consisting of sheets, plates, bars, wires, tubes, pipes, and forgings. 
     
     
         4 . The nickel-chromium-molybdenum-copper alloy of  claim 1 , wherein the alloy is in cast form. 
     
     
         5 . The nickel-chromium-molybdenum-copper alloy of  claim 1 , wherein the alloy is in powder metallurgy form. 
     
     
         6 . The nickel-chromium-molybdenum-copper alloy of  claim 1 , consisting essentially of:
 30 to 33 wt. % chromium   5.0 to 6.2 wt. % molybdenum   3.5 to 4.0 wt. % copper   up to 1.5 wt. % iron   0.3 to 0.7 wt. % manganese   0.1 to 0.4 wt. % aluminum   0.1 to 0.6 wt. % silicon   0.02 to 0.10 wt. % carbon   
     
     
         7 . The nickel-chromium-molybdenum-copper alloy of  claim 1 , consisting essentially of:
 31 wt. % chromium   5.6 wt. % molybdenum   3.8 wt. % copper   1.0 wt. % iron   0.5 wt. % manganese   0.4 wt. % silicon   0.3 wt. % aluminum   0.03 to 0.07 wt. % carbon   with a balance of nickel, nitrogen, impurities, and trace amounts of magnesium.   
     
     
         8 . The nickel-chromium-molybdenum-copper alloy of  claim 1 , consisting essentially of:
 31 wt. % chromium   5.6 wt. % molybdenum   3.8 wt. % copper   1.0 wt. % iron   0.5 wt. % manganese   0.4 wt. % silicon   0.3 wt. % aluminum   0.03 to 0.07 wt. % carbon   with a balance of nickel, nitrogen, impurities, trace amounts of magnesium and trace amounts of the rare earth elements.   
     
     
         9 . The nickel-chromium-molybdenum-copper alloy of  claim 1 , wherein the alloy contains at least one MC carbide former. 
     
     
         10 . The nickel-chromium-molybdenum-copper alloy of  claim 9 , wherein the MC carbide former is selected from the group consisting of titanium, niobium, tantalum and hafnium. 
     
     
         11 . The nickel-chromium-molybdenum-copper alloy of  claim 1 , wherein the alloy contains 0.20 to 0.56 wt. % titanium. 
     
     
         12 . The nickel-chromium-molybdenum-copper alloy of  claim 1 , wherein the alloy contains 0.30 to 1.12 wt. % niobium. 
     
     
         13 . The nickel-chromium-molybdenum-copper alloy of  claim 1 , wherein the alloy contains 0.60 to 2.24 wt. % tantalum. 
     
     
         14 . The nickel-chromium-molybdenum-copper alloy of  claim 1 , wherein the alloy contains 0.60 to 2.24 wt. % hafnium.