Year-end Sale % OFF 
Abstract
The method of local hardening of steel using rapid resistance heating was devised by focusing attention on one of the unique characteristics of the resistance heating that the heat generated by Joule heating per unit volume at the area in contact with electrodes is directly proportional to the square of current density and inversely proportional to the contact area ratio. This characteristic enables heating of steel for austenitizing essential to hardening even at the area in contact with the electrode of high thermal conductivity. In this study, effective measures for power control were considered to ensure stable achievement of local hardening in the case that there is an impedance change due to change of the treating objects or the treating positions in just the same object. A measure conclusively suggested as a strongly possible one was input heat control based on the integrated value of square of flowing current with respect to time, relating to the resistance heating characteristic in the present case. Effectiveness of the control was confirmed by experiments with an alternating current power supply to which the function described above was added.
Highlights
Though there have been various kinds of material processing which make use of resistance heating, that is, Joule heating by direct energizing, its application to metal-based powder sintering by F.V
The method for local hardening of steel parts was thought up by focusing attention on a unique characteristic of resistance heating at the electrode contact area, and successful performance of local hardening was demonstrated by application of proper resistance heating condition [8]
As for the local hardening treatment using resistance heating the effectiveness of power control by the integrated value of square of electric current with respect to time was examined using cold die steel, SKD11, as an experimental treating material, and the followings were found
Summary
Though there have been various kinds of material processing which make use of resistance heating, that is, Joule heating by direct energizing, its application to metal-based powder sintering by F.V. Its application has been expanding outside the field of sintering, and it is extended to hot stamping and die-quenching of steel sheet for automobile parts production which needs heating sheet materials [2, 3]. In these circumstances, one of the authors has researched into its application to fabrication of metal matrix composites and their simultaneous forming and joining to metal parts in the fabricating process [4, 5]. With a view to stable achievement of local hardening in use of an inexpensive AC power supply, the heating characteristic at the electrode contact area was considered and an effective measure was devised as to power control
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
