Galling-Free Cold and Warm Forging of Titanium Wires to Flat Plates by SiC-Coated SiC dies

Tatsuhiko Aizawa,Tatsuya Fukuda,Tomoaki Yoshino,Tomomi Shiratori

doi:10.25518/esaform21.1920

Abstract

Pure titanium and titanium alloys were difficult to be forged and press-forged because of their easiness in galling to die and punch surfaces during metal forming. β-SiC coated SiC dies were developed to perform a galling free cold forging of pure titanium wire up to the higher reduction of thickness than 50%. Since the thickness of this SiC coating was 4 mm, various cavities and micro-punches were formed into coating by micro-machining. The pure titanium and β-phase titanium alloy wires were employed as a work for cold and warm forging to investigate the effect of flow stress on the forging behavior up to the reduction of thickness by 70% under the controlled holding temperature. The contact interface of β-SiC coating to the work was precisely analyzed to describe the in situ solid lubricating process on the interface. The free carbon agglomerates isolated at the center of contact interface from the carbon supersaturated β-SiC coating, and, worked as a solid lubricant to prevent the β-SiC coating punch and die from galling during forging under high reduction of thickness.

Highlights

Titanium and titanium alloys have been utilized for high specific strength parts and members in airplanes [1] and for biocompatible tools in biomedical applications [2]
The reduction of thickness is varied up to 70% to describe the friction on the contact interface and to analyze the formation of the fresh surface in this flattening behavior
Precise analyses on the microstructure of contact interface is made to describe the titanium oxide debris film formation on the contact interface and to investigate the role of free carbon agglomerates from the SiC coating on the solid lubrication under dry cold and warm forging processes with a high reduction of thickness

Summary

Introduction

Titanium and titanium alloys have been utilized for high specific strength parts and members in airplanes [1] and for biocompatible tools in biomedical applications [2]. In their metal forming and forging, severe adhesion of work fragments and debris particles onto the dies induced their high friction and severe wear [3] and suppressed their workability. Thick SiC (Silicon Carbide) coating was proposed as a die material for upsetting the pure titanium wires [6,7]. The microstructure analysis on the contact interface [10,11] taught that the galling-free forging process was sustained by the in situ solid lubrication on the contact interface

Methods

Results

Conclusion