1. Nitriding Team Nitriding
The diffusion of nitrogen into the surface layers of low carbon steels at elevated temperature. The formation of nitrides in the surface layer creates increased mechanical properties.
Team Nitriding
Beth Blumhardt – Brent Fogal – Greg Mooren – Jana Young

2. Nitriding Introduction Benefits of Nitriding Types of Nitriding
Future of Nitriding
Process Determination
CVD Reaction
Deposition Process
Diffusion Depth
Process Results
Introduction

3. Nitriding Benefits Principal Reasons for Nitriding are:
Obtain High Surface Hardness
Obtain a Resistant Surface
Increase Wear Resistance
Increase Tensile Strength and Yield Point
Improve Fatigue Life
Improve Corrosion Resistance
(Except for Stainless Steels)
Benefits

4. Nitriding Background Improves Mechanical Properties Surface Hardness
Corrosion Resistance
Chemical Reaction
Nitrogen & Iron
Core Properties Not Effected
Temperature Range ºC
Below Tempering Temperature
White Layer By-Product
Thin
Hard Iron Nitride
Background

5. ***Lots of more nitriding methods for specific applications***
Process methods for nitriding include:
Gas
Liquid
Plasma
Bright
Pack
***Lots of more nitriding methods for specific applications***

6. Gas Nitriding Gas methods: Case-Hardening Process
Nitrogen Introduction
Surface of a Solid Ferrous Alloy
Suitable Temperature
Between 495 and 565°C (for Steels)
Nitrogenous Gas
Ammonia

7. Liquid Nitriding Liquid nitriding: Thermo-chemical Diffusion Treatment
Hardening Components With Repeatability. 
Salt Bath, at Less Critical Temperatures.
Preserves Dimensional Stability
Corrosion Protection
Exhibit Long-Term Resistance to Wear, Seizure, Scuffing, Adhesion and Fatigue.

8. Plasma Nitriding Set-Up Process
Vacuum Chamber
Pressure = 0.64 Pa
Pre-Heat Cycle
Surface Cleaning
Ion Bombardment
Control Gas Flow
N, H, CH4
Ionization by Voltage
Blue-Violet Glow
Wear Resistant Layer
Set-Up
Process

9. The Future of Nitriding
Replacing Liquid Nitriding
Environmental Effects
Ease of Control
More Complex Substrates
Performed at Lower Temperatures
Creates Higher Residual Stress <
PLASMA / ION NITRIDING

10. Problem Statement Gas Nitriding
How do the variables of nitriding steel affect the process and the mechanical properties of the surface?
The following variables were investigated:
Time
Temperature
Gas Velocity
Develop Process Model

11. CVD Equations
CVD Process
Calculations

12. CVD Reaction
Calculations

13. CVD Process
Calculations

14. Calculations Surface Composition
The Following Variables Were Used in The Calculation of C surface
η(T) ρ(T) D(T) δ(T,v) hmass(T,v)
Calculations

15. Case Depth
Calculations

16. Case Depth
Calculations

17. Case Depth
Calculations

18. CONCLUSION Time Effects Increase Diffusion Depth Temperature Effects
Surface Composition
Deposition Efficiency
Diffusion Rate
Diffusion Depth
Gas Velocity Effects
Replenishes Nitrogen Gas
Minimizes Stagnant Layer Thickness

19. CONCLUSION Continued Microstructural Effects Processing Temperature
Surface Microstructure
Mechanical Property Effects
Improves
Surface Hardness
Wear Resistance
Corrosion Resistance
Fatigue Life
Yield Strength
Lowers
Ductility
Fracture Toughness
Continued