Project Info
Fatigue Properties of Grain Refined High Hardness Steel
Robert Cryderman | rcryderm@mines.edu
Project will demonstrate fatigue strengths not previously achieved in rapidly heat treated steel components for high torque requirements such as electric or diesel powered vehicles.
More Information
Robert Cryderman and John Speer, “Microstructure and Notched Fracture Resistance of 0.56% C Steels After Simulated Induction Hardening,” Heat Treat 2017: Proceedings of the 29th ASM Heat Treating Society Conference, October 24–26, 2017, Columbus, Ohio, USA.
ABSTRACT
Historically, steels with carbon contents above about 0.45% C that are quenched to attain hardness above about 53 HRC (560 HV) are prone to premature brittle fracture when stressed in uniaxial or cyclic tension. In this study, six laboratory melted steels containing nominally 0.56% C and no grain refining additions (Ti, Al, V, or Nb) were heat treated on a Gleeble 3500® simulator to emulate thermal heating and quenching cycles for induction hardening. Limiting the peak heating temperatures and times produced a very fine grained austenite with final hardness above 60HRC (700HV). Fracture resistance measured by notched bend tests increased by up to 3 fold for the short low temperature heating cycles as compared to longer higher temperature cycles. Fracture surfaces showed trans-granular crack propagation for the short low temperature cycles as compared to inter-granular propagation for the longer higher temperature cycles.
Grand Engineering Challenge: Not applicable
Student Preparation
Qualifications
An interest in fatigue testing and microstructure.
A commitment to completing the project.
Some understanding of programming a test set-up.
Interest in hands-on mechanical testing.
Time Commitment
30-40 hours/month
Skills/Techniques Gained
Understanding of fatigue testing and techniques to evaluate fracture surfaces as well as underlying microstructure.
Mentoring Plan
Developing a work plan and outlining expectations for a final report of results. Introducing student to appropriate graduate students and laboratory staff for training on required equipment. Regular progress reviews and discussions.