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 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 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 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.

Observing Interfacial Sliding Processes in Solid–Solid Contacts

MRS Bulletin ◽  
2008 ◽  
Vol 33 (12) ◽  
pp. 1159-1167 ◽  
Author(s):  
Kathryn J. Wahl ◽  
W. Gregory Sawyer
Keyword(s):  
Thin Film ◽  
Optical Microscopy ◽  
Friction And Wear ◽  
Solid Lubricants ◽  
Solid Lubrication ◽  
Low Friction ◽  
Interfacial Sliding ◽  
Moving Contact ◽  
Powerful Approach

AbstractDirectly seeing into a moving contact is a powerful approach to understanding how solid lubricants develop low-friction, long-lived interfaces. In this article, we present optical microscopy and spectroscopy approaches that can be integrated with friction monitoring instrumentation to provide real-time, in situ evaluation of solid lubrication phenomena. Importantly, these tools allow direct correlation of common tribological events (such as variations in friction and wear) with the responsible sliding-induced mechanical and chemical phenomena. We demonstrate the utility of in situ approaches with applications to a variety of thin-film solid lubricants.

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.

scholarly journals In Vitro Frictional Forces Generated by Three Different Ligation Methods

2008 ◽  
Vol 78 (5) ◽  
pp. 917-921 ◽  
Author(s):  
Paola Gandini ◽  
Linda Orsi ◽  
Chiara Bertoncini ◽  
Sarah Massironi ◽  
Lorenzo Franchi
Keyword(s):  
Steel Wire ◽  
Testing Machine ◽  
Low Friction ◽  
Instron Testing Machine ◽  
Resistance To Sliding ◽  
Titanium Wire ◽  
Frictional Forces ◽  
Conventional Bracket ◽  
Wire Resistance

Abstract Objective: To test the hypothesis that there is no difference between the frictional forces produced by a passive self-ligating bracket (SLB) in vitro and a conventional bracket (CB) used with two types of elastomeric ligatures. Materials and Method: The brackets, wires and ligation methods used in vitro were a passive SLB and a CB used with two types of elastomeric ligatures (conventional elastomeric ligature [CEL] and unconventional elastomeric ligatures [UEL]). The bracket ligation systems were tested with two types of wires (0.014″ super elastic nickel titanium wire and 0.019″ × 0.025″ stainless steel wire). Resistance to sliding of the bracket/wire/ligature systems was measured with an experimental model mounted on the crosshead of an Instron testing machine with a 10 N load cell. Each sample was tested 10 consecutive times under a dry state. Results: Frictional forces close to 0 g were recorded in all tests with SLB and in all tests with UEL on CB with both wire types. Resistance to sliding increased significantly (87–177 g) (P < .05) when CEL on CB was used with both wires. Conclusion: UELs may represent a valid alternative to passive SLBs for low-friction biomechanics.

Analysis of Elliptical Rolling Contact Joints in Compression

2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Jacob R. Montierth ◽  
Robert H. Todd ◽  
Larry L. Howell
Keyword(s):  
Rolling Contact ◽  
Contact Interface ◽  
Force Transmission ◽  
Hertz Contact ◽  
Surface Geometry ◽  
Low Friction ◽  
High Quality ◽  
Gear Teeth ◽  
Revolute Joints ◽  
Pure Rolling

This paper presents elliptical rolling contact joints in compression as an alternative to circular rolling contact and conventional revolute joints where high quality force transmission—low friction and backlash—with variable output are desired. Parameters specific to the joint and its position are defined in terms of relative link angles and elliptical surface geometry. These relationships allow elliptical rolling contact joints to be incorporated in vector loop summations used in kinematic analysis. Notably, elliptical rolling contact is developed as the more general case of which circular rolling contact is a subset. Elliptical rolling contact joints are shown to offer several benefits over circular rolling contact, including reduced Hertz contact stresses, variable output velocity, maximum use of contact interface by distributing small rotations across surfaces of small curvature, reduced forces on constraining members, and no-slip pure rolling provided by either connecting links or flexures, without the need for gear teeth or friction.

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