Progress in control of nitriding potential in ASPN process

Abstract

A novel active screen plasma nitriding (ASPN) process provided excellent temperature homogeneity in the load and showed further progress in the control of nitriding potential. In addition to a variation of the nitrogen partial pressure in the process gas commonly used in the conventional plasma nitriding, the applied bias power strongly impacted the nitriding results. In the present work, an application of both methods for the control of nitriding potential in the ASPN process was systematically investigated for a wide range of process parameters to meet the treatment requirements for different types of engineering steel. A two-stage technique based on proper choice of process temperature and required nitriding potential in each stage has been applied in the ASPN process to avoid unnecessary compromises between sufficient thickness of the compound layer, the maximum case hardness and the acceptable nitriding hardness depth.

Keywords:

• Active screen plasma nitriding
• Nitriding potential
• Two-stage process
• Alloyed steels
• Nitriding hardness depth (NHD)

Acknowledgement

The authors thank German Research Foundation (DFG) for financial support in the frame of grant BI 418/20-1 and BI 418/20-2.