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Effect of nitrogen alloying on the microstructure and abrasive wear of stainless steels.
Hawk JA; Simmons JW; Raviers JC
J Mater Eng Perform 1994 Apr; 3(2):259-272
Alloying stainless steels with nitrogen has distinct advantages. Nitrogen is a strong austenite stabilizer and a potent solid-solution strengthener, and nitrogen has greater solubility than carbon in iron. This study investigates the relationship among nitrogen concentration, precipitate microstructure, and abrasive wear using two high-nitrogen stainless steel alloys: Fe-19Cr-5Mn-5Ni-3Mo (SSI) and Fe-16Cr-7Mn-5Ni (SS2). Alloy SSI contained 0.7 wt% N and was solution annealed at 1150 degrees C, thereby dissolving the nitrogen interstitially in the austenite. Subsequent aging, or cold work and aging, at 900 degrees C led to the grain-boundary, cellular, and transgranular precipitation of Cr 2 N. Alloy SS2 was remelted in a high pressure (200 MPa) N 2 atmosphere, leading to a spatial gradient of nitrogen in the alloy in the form of interstitial nitrogen and Cr 2 N and CrN precipitates. Nitrogen contents varied from a low of approximately 0.7 wt % at the bottom of the billet to a high of 3.6 wt % at the top. Nitrogen in excess of approximately 0.7 wt% formed increasingly coarser and more numerous Cr 2 N and CrN precipitates. The precipitate morphology created in alloy SSI due to aging, or cold work and aging, had little effect on the abrasive wear of the alloy. However, a decrease in the abrasive wear rate in alloy SS2 was observed to correspond to the increase in number and size of the Cr 2 N and CrN precipitates.
Steel industry; Stainless steel; Nitrogen compounds; Metal alloys; Metals; Author Keywords: abrasive wear; chromium nitride; nitrogen; stainless steel
J.A. Hawk, U.S. Bureau of Mines, Albany Research Center, Albany, USA
Issue of Publication
Journal of Materials Engineering and Performance
Page last reviewed: April 12, 2019
Content source: National Institute for Occupational Safety and Health Education and Information Division