Wear-resistant, partially uncoated steel parts and methods of producing same

Abstract

A wear-resistant steel part may be formed by hot forming and/or hardening a hardenable steel grade semifinished part. The steel part may be used, for example, as a processing, conveying, and/or crushing mechanism in agricultural machines, conveying machines, mining machines, or building machines. The semifinished part may be heated to a temperature above an Ac1 transformation temperature and then subsequently hot formed and/or hardened. The steel part may be particularly suitable for use with abrasive materials. To that end, the steel part may have at least one region that has been hardened to a depth of not more than 100 microns by surface hardening before the semifinished part is hot formed or hardened.”

1 .- 12 . (canceled) 
     
     
         13 . A method for producing a wear-resistant, uncoated steel part for a processing, conveying, and/or crushing mechanism of an agricultural machine, a conveying machine, a mining machine, or a building machine from a semifinished part comprising a hardenable steel grade, the method comprising:
 heating at least regions of the semifinished part to a temperature above an Ac1 transformation temperature;   at least partially subjecting the semifinished part to surface hardening by hardening a surface region to a depth of not more than 100 microns by heat treating the semifinished part in a heat treatment atmosphere comprising up to 25% by volume of H 2 , 0.1-10% by volume of NH3, H2O and balance N2 and impurities at a hold temperature of 600-900 degrees Celsius; and   at least one of hot forming or hardening the semifinished part.   
     
     
         14 . The method of  claim 13  wherein hardening the surface region comprises nitriding or carburizing. 
     
     
         15 . The method of  claim 13  wherein hardening the surface region comprises maintaining the semifinished part at the holding temperature for 30 to 120 seconds. 
     
     
         16 . The method of  claim 13  wherein the surface hardening is performed in a continuous hardening furnace. 
     
     
         17 . The method of  claim 13  wherein the semifinished part to be surface hardened comprises a manganese-boron steel or a TRIP steel. 
     
     
         18 . A wear-resistant, uncoated steel part formed of a hardenable steel grade and produced by hot forming and/or hardening a semifinished part, wherein the wear-resistant, uncoated steel part comprises a surface region that has been hardened to a depth of not more than 100 microns by surface hardening by nitriding prior to hot forming and/or hardening the semifinished part, wherein the wear-resistant, uncoated steel part is configured for use as a processing, conveying, and/or crushing mechanism in agricultural machines, conveying machines, mining machines, or building machines, wherein at least regions of the wear-resistant, uncoated steel part that are to be subjected to abrasive forces have been surface hardened. 
     
     
         19 . The wear-resistant, uncoated steel part of  claim 18  wherein after hot forming and/or hardening the steel part has at least the hardness of a base material of the steel part located under the surface region. 
     
     
         20 . The wear-resistant, uncoated steel part of  claim 18  wherein the steel part comprises at least one of a manganese-boron steel, a dual-phase steel, or a TRIP steel. 
     
     
         21 . The wear-resistant, uncoated steel part of  claim 18  wherein the surface region that has been hardened has before hot forming and/or hardening at least in some regions a hardness of 400-700 HV.