Nitrogen alloyed steel, spray compacted steels, method for the production thereof and composite material produced from said steel

Abstract

This invention relates to a nitrogen-alloyed steel with a high wear resistance, which is manufactured via spray compacting and has the following composition (in mass-%): C: 0.8-2.5%, N: 0.03-0.75%, Si: 0.15-1.8%, Mn: ≦1.0%, P: ≦0.03%, S: ≦0.05%, Cr: 4.0-11.5%, Mo: 0.5-6.0%, V: ≦4.0%, Nb: ≦4.0%, W: ≦3.5%, O 2 : ≦0.005%, other ally constituents as needed, residual iron and usual contaminants as the residue. The chemical composition has been optimized to have the carbide-carbonitride-forming elements satisfy a wear factor S v , and to maintain the silicon-nitrogen ratio V SiN in order to minimize the residual austenite contents. In addition, the invention relates to a procedure for manufacturing this type of steel and a composite manufactured using steel according to the invention. The steel material according to the invention has an improved wear resistance and dimensional stability.

1 . A nitrogen-alloyed steel with a high wear resistance fabricated via spray compacting and having the following composition (in mass-%): 
 C: 0.8-2.5%    N: 0.03-0.75%    Si: 0.15-1.8%    Mn: ≦1.0%    P: ≦0.03%    S: ≦0.05%    Cr: 5.0-11.5%    Mo: 0.5-6.0%    V: ≦4.0%    Nb: ≦4.0%    W: ≦3.5%    O 2 : ≦0.005%    additional alloy constituents as needed, with iron and usual contaminants as the residue,    wherein a wear factor S v  corresponding to the sum of its weighted contents of Cr, Mo, V, Nb and W satisfies the following condition:    0.55<S v <3.42    where: S v =(A Cr /9.33)+(A Mo /17.22)+(A V /3.92)+(A Nb /7.15)+(A W /14.14), 
 A Cr : Cr content in mass-%,  
 A Mo : Mo content in mass-%,  
 A V : V content in mass-%,  
 A Nb : Nb content in mass-%,  
 A W : W content in mass-%,  
 and wherein the silicon-nitrogen ratio V SiN  satisfies the following condition:  
 0.21≦V SiN ≦3.31  
 where:  
   V SiN =A Si +2 A N ,    A Si : Si content in mass-%,    A N : N content in mass-%.    
     
     
         2 . The steel according to  claim 1 , characterized in that it has a C content of 1.0-1.9 mass-%, an N content of 0.05-0.5 mass-%, an Si content of 0.15—1.5 mass-%, a Cr content of 5.0-10.0 mass-%, an Mo content of 0.5-5.5 mass-%, a V content ≦3.5 mass-%, an Nb content ≦3.5 mass-% and a W content ≦3.0%.  
     
     
         3 . The steel according to one of the preceding claims, characterized in that it contains up to 0.05 mass-% boron.  
     
     
         4 . The steel according to one of the preceding claims, characterized in that it contains up to 0.5 mass-% titanium.  
     
     
         5 . The steel according to one of the preceding claims, characterized in that it contains up to 0.5% zirconium.  
     
     
         6 . The steel according to one of the preceding claims, characterized in that it contains up to 0.25 mass-% aluminum.  
     
     
         7 . The steel according to one of the preceding claims, characterized in that it contains additional hard materials, such as titanium carbide, silicon carbide, niobium carbide, chromium carbide, titanium nitride, tungsten carbide, in its matrix, which were injected into the spray jet during spray compacting as solid particles.  
     
     
         8 . A procedure for manufacturing a steel according to one of the preceding claims, characterized in that 
 the steel is spray compacted using nitrogen as the spray gas,    the steel is thermoformed after spray compacting at initial temperatures of up to 1150° C.,    the thermoformed steel is cooled,    the cooled steel is reheated to an austenizing temperature of 1075° C. to 1225° C.,    the reheated steel is quenched, and    the quenched steel is tempered at temperatures of 150° C.-625° C.    
     
     
         9 . The procedure according to  claim 8 , characterized in that tempering takes place at temperatures of between 150° C. and 300° C.  
     
     
         10 . The procedure according to  claim 8 , characterized in that tempering takes place at temperatures of between 500° C. and 625° C.  
     
     
         11 . A composite material with at least one first layer generated by a first steel and at least a second layer formed by nitrogen-alloyed, spray-compacted steel according to one of  claims 1  to  7 , wherein the steel in the first layer has a different composition than the spray-compacted steel.