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

2021 ◽  
Author(s):  
Tatsuhiko Aizawa ◽  
Tomoaki Yoshino ◽  
Tomomi Shiratori ◽  
Tatsuya Fukuda
Keyword(s):  
Pure Titanium ◽  
Cold Forging ◽  
Contact Interface ◽  
Flat Plates ◽  
Β Phase ◽  
Titanium Wire ◽  
High Reduction ◽  
Warm Forging ◽  
Holding Temperature

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.

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

2021 ◽  
Vol 11 (2) ◽  
pp. 595
Author(s):  
Tatsuhiko Aizawa ◽  
Tomoaki Yoshino ◽  
Yohei Suzuki ◽  
Tomomi Shiratori
Keyword(s):  
Pure Titanium ◽  
Solid Lubrication ◽  
Cold Forging ◽  
Contact Interface ◽  
Metallic Titanium ◽  
Low Friction ◽  
Debris Particles ◽  
Titanium Wire ◽  
Oxide Debris

A bare AISI420J2 punch often suffers from severe adhesion of metallic titanium as well as titanium oxide debris particles in dry, cold forging of biomedical titanium alloys. This punch was plasma-carburized at 673 K for 14.4 ks to harden it up to 1200 HV on average and to achieve carbon supersaturation in the carburized layer. This plasma-carburized punch was employed in the cold, dry forging of a pure titanium wire into a flat plate while reducing the thickness by 70%. The contact interface width approached the forged workpiece width with increasing the reduction ratio. This smaller bulging deformation reveals that the workpiece is upset by homogeneous plastic flow with a lower friction coefficient. This low-friction and anti-galling forging process was sustained by an in situ solid lubrication mechanism. Unbound free carbon was isolated from the carbon-supersaturated AISI420J2 matrix and deposited as a thin tribofilm to protect the contact interface from mass transfer of metallic titanium.

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

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2536
Author(s):  
Tatsuhiko Aizawa ◽  
Tomoaki Yoshino ◽  
Yohei Suzuki ◽  
Tomomi Shiratori
Keyword(s):  
Solid Lubricant ◽  
Pure Titanium ◽  
Solid Lubrication ◽  
Single Shot ◽  
Contact Interface ◽  
Forging Process ◽  
Titanium Wire ◽  
High Reduction ◽  
Residual Strains

A tool steel type SKD11 punch was plasma carburized at 673 K for 14.4 ks at 70 Pa to make carbon supersaturation. This carburized SKD11 punch was employed for upsetting the pure titanium wire with the diameter of 1.00 mm up to the reduction of thickness by 70% in a single shot. Its contact interface to titanium work was analyzed to describe the anti-galling behavior in this forging. Little trace of titanium proved that the galling process was suppressed by the in situ solid lubrication. The isolated free carbon agglomerates are wrought as a solid lubricant to sustain the galling-free forging process. This anti-galling upsetting reduced the residual strains in the forged wires. A long titanium wire with a length of 45 mm was incrementally upset to yield the titanium ribbon with a thickness of 0.3 mm, the width of 2.3 mm, and the length of 50 mm. The grain size of original pure titanium was much reduced to 2 μm on average. A micro-pillared microtexture was imprinted onto this forged titanium ribbon.

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

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3780 ◽  
Author(s):  
Tatsuhiko Aizawa ◽  
Tomoaki Yoshino ◽  
Tatsuya Fukuda ◽  
Tomomi Shiratori
Keyword(s):  
Pure Titanium ◽  
Cold Forging ◽  
Initial Contact ◽  
Titanium Oxides ◽  
Contact Interface ◽  
Metallic Titanium ◽  
Industrial Grade ◽  
Titanium Wire ◽  
Grade Ii

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.

scholarly journals Thick β-SiC CVD-Coated SiC Die System for Dry Cold Forging of Metals

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 539 ◽  
Author(s):  
Tatsuhiko Aizawa ◽  
Tomoaki Yoshino ◽  
Ko-Ichi Ito ◽  
Tatsuya Fukuda
Keyword(s):  
Stainless Steel ◽  
Pure Titanium ◽  
Chemical Vapor ◽  
Cold Forging ◽  
Material Transfer ◽  
Work Material ◽  
Pentagonal Prism ◽  
Edx Analyses ◽  
Mechanical Machining

A thick β-SiC CVD (chemical vapor deposition)-coated SiC device was developed as a new punch and die system for dry, cold forging of pure titanium and austenitic stainless-steel works. This β-SiC coating thickness was 4 mm, enough to make mechanical machining of a cavity into β-SiC coating core die. These β-SiC-coated punch and core dies were fixed into the cassette die for dry, cold forging experiments. The stainless steel and titanium wires with diameters of 1.0 mm were employed as the work material. Different from the conventional metallic and ceramic die systems suffering from work material transfer, this system sustained the galling-free cold, dry forging behavior up to a higher reduction of thickness than 30%. The power to stroke the relationship was in situ monitored to describe this forging behavior up to the specified reduction of the wires together with observations on the geometric change from a circular wire to a pentagonal prism bar. Precise scanning electron microscopy-electron-dispersive X-ray spectroscopy (SEM-EDX) analyses were performed to describe the material compatibility on the contact interface between β-SiC coating and elastoplastically deforming works.

Characterization of Local Mechanical Properties of X80 Pipeline Girth Welds Using Advanced Techniques

2016 ◽  
Author(s):  
Abdelbaset R. H. Midawi ◽  
Y. Kisaka ◽  
E. B. F. Santos ◽  
A. P. Gerlich
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Weld Zone ◽  
Pure Titanium ◽  
Strength Distribution ◽  
Image Correlation ◽  
Instrumented Indentation ◽  
Titanium Wire ◽  
Girth Welds

An instrumented indentation technique is proposed as a method to directly measure the local yield strength distribution in each zone of gas metal arc welds produced in X80 linepipe. The joints were produced with different microstructures and mechanical properties by applying shielding gases with varying Ar/CO2 ratios of 50 to 15% CO2 and the addition of a pure titanium wire into the weld pool was used to achieve in-situ alloying. The local yield strength distribution for each weld zone was then measured with instrumented indentation. The mapped yield strength distributions measured by instrumented indentation was compared to the hardness distribution. In addition, the yield strength of each zone obtained by instrumented indentation were then compared to tensile test results from Digital Image Correlation (DIC), in order to obtain stress-strain curves for each microstructural zone of the weld. The yield strength results obtained from both techniques are in good agreement, suggesting that instrumented indentation can be useful method to measure the local yield strengths of specific regions in a welded joint.

In Situ Produced MMC Layer by Laser Melt Injection

2010 ◽  
Vol 649 ◽  
pp. 61-66
Author(s):  
Zoltán Kálazi ◽  
Viktória Janó ◽  
Gábor Buza
Keyword(s):  
Carbon Content ◽  
Composite Layer ◽  
Pure Titanium ◽  
Base Material ◽  
Titanium Content ◽  
Steel Sample ◽  
Low Carbon ◽  
The Matrix ◽  
Ti Powder

Tungsten (W) based alloy composite layer reinforced with TiC particles has been successfully prepared on unalloyed steel sample by LMI technology. In order to obtain in situ produced TiC reinforcement, pure titanium has been introduced to the melt pool. WC powder was added for increasing the carbon content of the layer in order to avoid the softening of the matrix (with low carbon content) during TiC formation. The present study aims to investigate the optimum amount of injected WC and Ti powder to improve wear resistance and hardness of the layer. Samples were investigated using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The maximum hardness of the layer has been reached ~900HV in case of 2-4wt% of titanium content. Ti has been collected all of the carbon from the matrix when titanium content was 9,6wt%, which resulted that the austenite and (Fe,W)6C phases have been disappeared. Only α-Fe and TiC phases were presented in the layer. The hardness of the layer reduced to the hardness of the base material.

scholarly journals In Situ Formation of a Metastable β-Ti Alloy by Laser Powder Bed Fusion (L-PBF) of Vanadium and Iron Modified Ti-6Al-4V

Metals ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 1067 ◽  
Author(s):  
Florian Huber ◽  
Thomas Papke ◽  
Christian Scheitler ◽  
Lukas Hanrieder ◽  
Marion Merklein ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Homogeneous Element ◽  
Alloy Formation ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Β Phase ◽  
Stabilizing Effect

The aim of this work is to investigate the β-Ti-phase-stabilizing effect of vanadium and iron added to Ti-6Al-4V powder by means of heterogeneous powder mixtures and in situ alloy-formation during laser powder bed fusion (L-PBF). The resulting microstructure was analyzed by metallographic methods, scanning electron microscopy (SEM), and electron backscatter diffraction (EBSD). The mechanical properties were characterized by compression tests, both prior to and after heat-treating. Energy dispersive X-ray spectroscopy showed a homogeneous element distribution, proving the feasibility of in situ alloying by LPBF. Due to the β-phase-stabilizing effect of V and Fe added to Ti-6Al-4V, instead of an α’-martensitic microstructure, an α/β-microstructure containing at least 63.8% β-phase develops. Depending on the post L-PBF heat-treatment, either an increased upsetting at failure (33.9%) compared to unmodified Ti-6Al-4V (28.8%), or an exceptional high compressive yield strength (1857 ± 35 MPa compared to 1100 MPa) were measured. The hardness of the in situ alloyed material ranges from 336 ± 7 HV0.5, in as-built condition, to 543 ± 13 HV0.5 after precipitation-hardening. Hence, the range of achievable mechanical properties in dependence of the post-L-PBF heat-treatment can be significantly expanded in comparison to unmodified Ti-6Al-4V, thus providing increased flexibility for additive manufacturing of titanium parts.

An In Situ Observation of Slip Deformation in a Compressed Ti-Mo-Al Single Crystal

2018 ◽  
Vol 941 ◽  
pp. 1463-1467
Author(s):  
Ryotaro Hara ◽  
Masaki Tahara ◽  
Tomonari Inamura ◽  
Hideki Hosoda
Keyword(s):  
Martensitic Transformation ◽  
Slip System ◽  
Single Crystal ◽  
Deformation Behavior ◽  
Room Temperature ◽  
Martensite Phase ◽  
Slip Direction ◽  
Β Phase ◽  
Slip Deformation

The stress-induced martensitic transformation and slip deformation behavior were investigated by the compression test with anin-situobservation in a Ti-6Mo-10Al (mol %) alloy single crystal. Owing to the stress-induced martensitic transformation from the parent β phase to the α′′ martensite phase, the single crystal of α′′ martensite without internal twinnings was successfully obtained at room temperature. By further compression, the slip deformation occurred in the single crystal of α′′ martensite. The operated slip system in the α′′ martensite was analyzed by the two face trace analyses, and the slip direction was determined to be []o.

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