18CrNiMo7-6 with TRIP-Effect for Increasing the Damage Tolerance of Gear Components — Part II: Microstructure and Mechanical Properties

Margarita D. Bambach; Andreas Stieben; Wolfgang Bleck

doi:10.4028/www.scientific.net/MSF.783-786.639

Paper Titles

Beta-Forging of Ti6Al4V Titanium Alloy Powders Consolidated by HIP: Plastic Flow and Strain-Rate Relation
p.613

Tensile Strength and Impact Toughness of Gallium-Bearing Near-α Titanium Alloys
p.619

Effect of Multipass Welding Using a Low Transformation Temperature Filler Metal on Residual Stress and Toughness
p.627

18CrNiMo7-6 with TRIP-Effect for Increasing the Damage Tolerance of Gear Components — Part I: Alloy Design
p.633

18CrNiMo7-6 with TRIP-Effect for Increasing the Damage Tolerance of Gear Components — Part II: Microstructure and Mechanical Properties
p.639

Finite Element Implementation of a Bonding Model and Application to Roll Bonding of Aluminum Sheets of Largely Different Yield Strength
p.644

Development of Ultrafine Grained Austenitic Stainless Steels by Large Strain Deformation and Annealing
p.651

Microstructural and Mechanical Properties of the Intercritically Reheated Coarse Grained Heat Affected Zone (ICCGHAZ) of an API 5L X80 Pipeline Steel
p.657

Hybrid Fiber Laser – Arc Welding of High Strength Low Alloy Steel
p.663

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18CrNiMo7-6 with TRIP-Effect for Increasing the Damage Tolerance of Gear Components — Part II: Microstructure and Mechanical Properties

Abstract:

High performance components such as gear wheels shall be resistant to rolling-contact fatigue. This type of failure is usually caused by effects occurring on a microscopic scale, such as crack initiation at non-metallic inclusions. Much effort has been invested so far in improving the steel cleanliness. However, these high performance components often do not reach the desired service life. Preliminary failure within the guarantee terms still occurs which leads to high warranty costs. Alternative to improving steel cleanliness, the damage tolerance of high performance components could be increased by inducing the TRIP-effect around the crack tip. Due to high local strain hardening, martensite transformation occurs. The high compressive stresses related to it could delay or stop crack propagation by reducing stress concentrations via plastic deformation. In part II of this study, the microstructures and mechanical properties of the steels modified via Al-alloying and heat treated in process routes according to part I are compared to conventional 18CrNiMo7-6. Special interest is paid to the stability of the residual austenite as well as to the change in strain hardening rate under tension.