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 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 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 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 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.

Compact Endoscopy of the Larynx

2003 ◽  
Vol 112 (2) ◽  
pp. 113-119 ◽  
Author(s):  
Christoph Arens ◽  
Thomas Dreyer ◽  
Hiltrud Glanz ◽  
Karin Malzahn
Keyword(s):  
Laryngeal Cancer ◽  
Carcinoma In Situ ◽  
Preoperative Assessment ◽  
Laryngeal Mucosa ◽  
Grade Ii ◽  
Cancerous Lesions ◽  
Epithelial Layers ◽  
Epithelial Lesions ◽  
Autofluorescence Endoscopy

In order to improve preoperative assessment of suspected precancerous and cancerous lesions of the larynx, we examined 83 patients by compact endoscopy (combination of autofluorescence and contact endoscopy) during microlaryngoscopy in a pilot study. The intraoperative findings were related to histopathologic examination. Cancerous laryngeal mucosa was illuminated during autofluorescence endoscopy by use of blue filtered light (D-light AF system) for optical demarcation of the lesion. After staining the mucosa with methylene blue (1%), we performed contact endoscopy. During autofluorescence examination of the endolaryngeal mucosa, the appearance of precancerous and cancerous lesions varied between opaque light areas and darker reddish areas. By contact endoscopy, it was possible to observe the cells, nuclei, and cytoplasm, as well as different degrees of abnormality. Histopathologic findings of 83 patients revealed laryngeal dysplasia (grade I in 29 patients, grade II in 15, and grade III or carcinoma in situ in 8) and laryngeal cancer (31 patients). In 73 cases (88%), the findings of compact endoscopy corresponded to those of histopathology. In 5 cases, epithelial lesions were overestimated because of inflammation and scarring, and 5 cases were underestimated because of hyperkeratotic thickening of the mucosa covering basal epithelial layers with focal dysplasia of grades II and III, carcinoma in situ, and microinvasive cancer. We conclude that compact endoscopy enables the laryngologist to assess laryngeal cancer and its preceding lesions more accurately during microlaryngoscopy.

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.

Main Defects Observed in Titanium GRADE II and 316L Stainless Steel Elements Obtained by Selective Laser Melting

2020 ◽  
Vol 308 ◽  
pp. 33-50
Author(s):  
Anna Woźniak ◽  
Marcin Adamiak
Keyword(s):  
Stainless Steel ◽  
Energy Density ◽  
Selective Laser Melting ◽  
Process Parameters ◽  
Defect Formation ◽  
Pure Titanium ◽  
Parameters Optimization ◽  
Laser Melting ◽  
Grade Ii ◽  
Titanium Grade

Selective Laser Melting SLM is one of the most popular three dimensional printing methods, which can be used for manufactured real elements (with high geometrical complexity) in many application, such as medicine, automotive or aerospace industries. The SLM final parts are characterized by high mechanical properties and satisfactory physicochemical properties. However, the properties of parts depend of process parameters optimization. In this paper, effects of processing parameters, such as laser power P, scanning speed SP, layer thickness t or point distance PD on defect formation and relative densities of manufactured elements are explored. For the purpose the stainless steel 316L and pure titanium Grade II are used. The process optimization were carried out according to the formula of energy density, which is delivered to the powder material. The stainless steel samples were divided into 12 groups, depends of the energy density. The titanium parts were printed at the same value of energy, and the process parameters are changed. The microscope observation and relative density measurements were carried out. Based on the obtained results, it can be confuted that the SLM parameters have a significant effect on the samples properties and the mechanism formed defect in both material are similar.

Photocatalytic activity and antibacterial efficacy of UVA-treated titanium oxides

2020 ◽  
Vol 35 (4-5) ◽  
pp. 500-514
Author(s):  
Haden Andrew Johnson ◽  
Randall Scott Williamson ◽  
Mary Marquart ◽  
Joel David Bumgardner ◽  
Amol V Janorkar ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Pure Titanium ◽  
Antimicrobial Properties ◽  
Bacterial Attachment ◽  
Mixed Phase ◽  
Titanium Oxides ◽  
Commercially Pure Titanium ◽  
Mixed Acid ◽  
Uva Irradiation ◽  
Titanium Grade

Studies have shown ultraviolet-A (UVA) irradiation of crystalline titanium oxides leads to the production of reactive oxygen species (ROS) via a photocatalytic process. The ROS exhibit antimicrobial properties that may be of benefit in preventing bacterial attachment to implant devices. Recent studies have suggested a potential benefit of mixed anatase and rutile oxides and dopants on the photocatalytic properties of titanium oxides. The goal of this work was to compare the photocatalytic activity of different anodized commercially pure titanium grade 4 (CPTi4) surfaces. CPTi4 specimens were anodized in three mixed-acid electrolytes to create crystalline oxide surfaces that were either primarily anatase, primarily rutile, or a combination of anatase and rutile. Additionally, the primarily anatase and combination oxides incorporated some phosphorous from the phosphoric acid component in the electrolyte. The photocatalytic activity of the anodized specimens was measured using both methylene blue (MB) degradation assay and comparing the attachment of S. aureus under irradiation with UVA light of differing intensities (1 mW/cm2, 8 mW/cm2, and 23 mW/cm2). Primarily rutile oxides exhibited significantly higher levels of MB degradation after exposure to 1 mW/cm2 UVA lights. Primarily rutile specimens also had the largest reduction in bacterial attachment followed by the mixed phase specimens and the primarily anatase specimens at 1 mW/cm2 UVA lights. Phosphorous-doped, mixed phase oxides exhibited an accelerated MB degradation response during exposure to 8 mW/cm2 and 23 mW/cm2 UVA lights. All anodized and unanodized CPTi4 groups revealed similar S. aureus attachment at the two higher UVA intensities. Although MB degradation assay and the bacteria attachment assay both confirmed photocatalytic activity of the oxides formed in this study, the results of the MB degradation assay did not accurately predict the oxides performance against S. aureus.

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