Dry Cold Forging of Pure Titanium Wire to Thin Plate with Use of β-SiC Coating Dies

Abstract

Dense β-SiC coating with 3C-structure was utilized as a dry cold forging punch and core-die. Pure titanium T328H wires of industrial grade II were employed as a work material. No adhesion or galling of metallic titanium was detected on the contact interface between this β-SiC die and titanium work, even after this continuous forging process, up to a reduction in thickness by 70%. SEM (Scanning Electron Microscopy) and EDX (Electron Dispersive X-ray spectroscopy) were utilized to analyze this contact interface. A very thin titanium oxide layer was in situ formed in the radial direction from the center of the contact interface. Isolated carbon from β-SiC agglomerated and distributed in dots at the center of the initial contact interface. Raman spectroscopy was utilized, yielding the discovery that this carbon is unbound as a free carbon or not bound in SiC or TiC and that intermediate titanium oxides are formed with TiO2 as a tribofilm.

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

“…As had been reported in [10,11], this contact interface consists of two regions in Fig. 4a; e.g., a black zone or the region-A at the center of the contact interface and white the zones or the region-B, sand-witching this black zone.…”

“…In addition, a titanium wire was successfully upset in cold and dry till the reduction of thickness reached to 35 % [8][9]. 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.…”

Anti-Galling Cold, Dry Forging of Pure Titanium by Plasma-Carburized AISI420J2 Dies

“…This anti-galling process was sustained under in situ solid lubrication by the free carbon isolated from the carbon-supersaturated β-SiC coating surface and under the in situ formation of intermediate titanium oxide tribofilms on the contact interface. Owing to this galling-free mechanism, a pure titanium wire was forged under cold and dry conditions with a 70% reduction in thickness [5]. Hence, simple shaping and upsetting can be put into practice in industries by using these β-SiC-coated SiC die systems.…”

Free-Forging of Pure Titanium with High Reduction of Thickness by Plasma-Carburized SKD11 Dies

“…As surveyed in [ 3 ], these galling processes were difficult to be prevented from upsetting and shaping the pure titanium works with high reduction of thickness without an innovative change of die materials. Thick β -SiC coated SiC die material was the first candidate to put the anti-galling forging in dry and cold into practice [ 4 , 5 , 6 ]. Those chemical vapor deposition (CVD)-coated β -SiC layers had stable 3C-structure with supersaturated carbon solute contents.…”

“…The carbon agglomerates isolated from the carbon supersaturated β -SiC coating and wrought as a solid lubricant together with low friction by the in situ formed deformable intermediate titanium oxide tribofilm [ 5 ]. Due to this in situ solid lubrication, the titanium wire with a diameter of 1.0 mm was reduced to a rectangular plate with a thickness of 0.3 mm by a single-shot upsetting [ 6 ]. As surveyed in [ 7 ], this in situ solid lubrication by the free carbon dots and tribofilms plays a role in the die material selection to make galling-free, dry, cold forging in practice.…”