Investigation on structural and tribological properties of borided gear steel after phase homogenization


Arslan M., Ok A. C. , Kartal Şireli G., Timur S.

SURFACE & COATINGS TECHNOLOGY, vol.429, 2022 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 429
  • Publication Date: 2022
  • Doi Number: 10.1016/j.surfcoat.2021.127967
  • Journal Name: SURFACE & COATINGS TECHNOLOGY
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, PASCAL, Aerospace Database, Biotechnology Research Abstracts, Chemical Abstracts Core, Chimica, Communication Abstracts, Compendex, INSPEC, Metadex, Civil Engineering Abstracts
  • Keywords: Boriding, CRTD-Bor, Fe2B, AISI 8620, Gear steel, Wear, Phase homogenization, ABRASIVE WEAR BEHAVIOR, AISI 8620 STEEL, KINETICS, LAYERS, EVOLUTION, HARDNESS, GROWTH, CARBON
  • Istanbul Technical University Affiliated: Yes

Abstract

This study focused on the structural and mechanical characterizations of AISI 8620 gear steel after a novel combined treatment (CRTD-Bor: Cathodic Reduction and Thermal Diffusion based boriding and subsequent PH: phase homogenization). Initially the effects of CRTD-Bor process parameters on the modified layer depth and chemistry were investigated at two sets of experiments as follows i) temperature examinations-15 min of CRTDBor at 950, 1000, 1050 and 1100 degrees C ii) duration investigations - at 950 degrees C for 15, 30, 60 and 120 min of CRTDbor. After that, PH treatment was integrated into CRTD-Bor to obtain industrially-desired monolithic Fe2B coatings. The optimized parameter of the dual treatment was found as 15 min of CRTD-Bor and subsequently 45 min of PH at 1000 degrees C, which resulted in 100 mu m thick sole Fe2B layer having 1600 +/- 100 HV hardness along with the perfect adhesion-HF1 quality. The tribological properties were evaluated by sliding wear tests in pin-on-disc configuration under dry and lubricated conditions. Since the wear in gear systems is of concern, wear tests were conducted to unborided pin/unborided disc, borided pin/unborided disc and borided pin/borided disc tribocouples. For both environments, the unborided tribo-pairs exhibited the highest loss whereas the borided tribo-couples had no measurable wear. Results of tribological tests revealed that the combined treatment successfully improved the wear resistance of the gears working in relative motions.