Titanium Alloy Plates Research Articles

Shock Physics Analysis to Support Optical Signature Prediction in Hypervelocity Impacts

In a recent series of light-gas-gun experiments performed at Sandia National Laboratories, aluminum projectiles impacted titanium alloy plates at 6km/s, with a variety of witness plates downstream. The radiative characteristics of the target debris cloud were measured using a combination of time-resolved visible emission spectroscopy and high-speed wavelength-filtered camera imagery. This paper will describe the analyses performed in support of the test series using the CTH shock-physics package from Sandia, discuss the methodology developed to port CTH results into radiation-physics codes, and provide comparisons between CTH results and experimental observations of debris-cloud shape. The combination of high-fidelity shock-physics analysis and high-fidelity spectral analysis of the shock-physics results represents a first-principles approach toward optical signature prediction in hypervelocity impacts.

A comparative study of pulsed Nd:YAG laser welding and TIG welding of thin Ti6Al4V titanium alloy plate

This paper reports on a study aiming at comparing properties of the Ti6Al4V titanium alloy joints between pulsed Nd:YAG laser welding and traditional fusion welding. To achieve the research purpose, Ti6Al4V titanium alloy plates with a thickness of 0.8mm were welded using pulsed Nd:YAG laser beam welding (LBW) and gas tungsten arc welding (TIG), respectively. Residual distortions, weld geometry, microstructure and mechanical properties of the joints produced with LBW and TIG welding were compared. During the tensile test, with the aid of a high speed infrared camera, evolution of the plastic strain within tensile specimens corresponding to LBW and TIG welding were recorded and analyzed. Compared with the TIG, the welded joint by LBW has the characters of small overall residual distortion, fine microstructure, narrow heat-affected zone (HAZ), high Vickers hardness. LBW welding method can produce joints with higher strength and ductility. It can be concluded that Pulsed Nd:YAG laser welding is much more suitable for welding the thin Ti6Al4V titanium alloy plate than TIG welding.

Monitoring in precision metal drilling process using multi-sensors and neural network

This paper presents a new method to estimate hole diameters and surface roughness in precision drilling processes, using coupons taken from a sandwich plate composed of a titanium alloy plate (Ti6Al4V) glued onto an aluminum alloy plate (AA 2024T3). The proposed method uses signals acquired during the cutting process by a multisensor system installed on the machine tool. These signals are mathematically treated and then used as input for an artificial neural network. After training, the neural network system is qualified to estimate the surface roughness and hole diameter based on the signals and cutting process parameters. To evaluate the system, the estimated data were compared with experimental measurements and the errors were calculated. The results proved the efficiency of the proposed method, which yielded very low or even negligible errors of the tolerances used in most industrial drilling processes. This pioneering method opens up a new field of research, showing a promising potential for development and application as an alternative monitoring method for drilling processes.

In vitro degradation of electrodeposited calcium phosphate coatings by osteoclast-like cells

The aim of this study is to investigate the in vitro degradation of electrolytically deposited calcium phosphate coatings in the presence of osteoclast-like cells. Titanium alloy plates electrolytically coated with calcium phosphate with or without chitosan were incubated with RAW264.7 cells for 14 days. The TRAP activity was measured and the cell attachment and proliferation capacity were analyzed. The calcium ion concentrations in the culture medium before and after incubation were calculated. Both coatings were observed with scanning electron microscopy and characterized through an x-ray diffractometer and Fourier transform infrared spectrum. The RAW264.7 cells differentiated into TRAP-positive osteoclast-like cells on both coatings after 7 days. Although presenting different cell attachment pattern, the RAW264.7 cells demonstrated the similar TRAP activity and proliferation capacity. It was found that the calcium ion concentrations in the medium decreased at the beginning, but increased after 11 and 14 days. The chitosan containing coatings had higher Ca2+ concentration in the medium compared to that without chitosan. Besides, the incubation of coatings with cells induced higher calcium ion concentrations than those without cells at day 11 and day 14. Despite the structural changes of dissolution pits and osteoclastic resorption lacunae present on both coatings, the x-ray diffractometer and Fourier transform infrared spectrum showed few alternations in their chemical compositions. Both electrodeposited calcium phosphate coatings can be resorbed by osteoclast-like RAW264.7 cells and dissolved in the culture medium in vitro. The degradation brings little change to the chemical compositions of both coatings.

Temperature and stress fields in electron beam welded Ti-15-3 alloy to 304 stainless steel joint with copper interlayer sheet

Electron beam welding of Ti-15-3 alloy to 304 stainless steel (STS) using a copper filler metal was carried out. The temperature fields and stress distributions in the Ti/Fe and Ti/Cu/Fe joint during the welding process were numerically simulated and experimentally measured. The results show that the rotated parabola body heat source is fit for the simulation of the electron beam welding. The temperature distribution is asymmetric along the weld center and the temperature in the titanium alloy plate is higher than that in the 304 STS plate. The thermal stress also appears to be in asymmetric distribution. The residual tensile stress mainly exists in the weld at the 304 STS side. The copper filler metal decreases the peak temperature and temperature grade in the joint as well as the residual stress. The longitudinal and lateral residual tensile strengths reduce by 66 MPa and 31 MPa, respectively. From the temperature and residual stress, it is concluded that copper is a good filler metal candidate for the electron beam welding of Ti-15-3 titanium alloy to 304 stainless steel.

Effect of ionic products of dicalcium silicate coating on osteoblast differentiation and collagen production via TGF-β1 pathway

In this work, the medium containing ionic products of dicalcium silicates (Ca(2)SiO(4)) for culturing MG63 cells was prepared by immersing a titanium alloy plate with the plasma sprayed Ca(2)SiO(4) coatings in DMEM solution. The effect of the ionic products on cellular differentiation, collagen production, and local growth factors (prostaglandin E(2) [PGE(2)] and transforming growth factor-β [TGF-β1]) of osteoblast-like MG63 cells were investigated. The normal DMEM was also used to culture MG63 cells as the control group. Differentiation of cell was evaluated by detecting alkaline phosphatase (ALP) activity and osteocalcin (OC) synthesis as well as their gene expression. Collagen production was analyzed by Sircol assay. The levels of PGE(2) and TGF-β1 in culture medium were measured using enzyme-linked immunosorbent assay (ELISA). The gene expressions of TGF-β receptors (TGF-β RI and TGF-β RII) were also measured by real-time PCR technology. MG63 cells cultured in DMEM containing ionic products of Ca(2)SiO(4) coating showed enhanced differentiation and increased collagen production. The results obtained from ELISA showed that the levels of PGE(2) and TGF-β1 in experimental group were higher than that in control. The gene expression of TGF-β receptors was upregulated, indicating that more TGF-β1 bonded to their receptors which produce more effects on the osteoblastic activity, leading to enhanced differentiation and synthetic activity of osteoblast. It is concluded that ionic products of Ca(2)SiO(4) coating may enhance cellular differentiation and collagen production by influencing TGF-β1 pathway.

Characterization of Friction Stir Welded Joints in TA15 Titanium Alloy Plates

Friction stir welding (FSW) was applied to TA15 titanium alloy plates. Welds were produced by employing rotational speed of 375rpm and a travel speed of 23.5mm/min.The microstructure and mechanical properties of friction stir welded joints were investigated. Flow pattern of the materials also were analysed. The stir zone (SZ) was characterized by α-phase and β-phase, but the size of the grain in the middle of the SZ was much finer than that of the upper. The interface between the base metal (BM) and SZ is associated with the flow state of the plastic materials. Results of transverse tensile test indicated that all the joints exhibited lower tensile strength than the BM, and the maximum tensile strength of the as-welded joint is about 97.6% of the average strength of the BM.

Fatigue Property of Welded Joints of Ti<sub>6</sub>Al<sub>4</sub>V Titanium Alloy in Corrosion Environment

The fatigue property of welded specimen of different form of Ti6Al4V Titanium Alloy plate was researched in the environmental condition of atmosphere and salt fog,The test results indicate the holes along weld seam in welding specimen have great influence on fatigue property, The fatigue life of Ti6Al4V Titanium Alloy doesn’t low under the salt fog condition in high stress range. The salt fog brings about the influence on fatigue life obviously at the same corrosion condition with fatigue stress lowering.

Impact of implanted metal plates on radiation dose distribution in vivo by Monte Carlo code

Objective To investigate the impact of metal plate on radiation dose distribution by Monte Carlo (MC) code. Methods The metal plates with 0. 4 thick were placed in water at 5 cm, all the plate irradiated with 6 MV X-ray were simulated by MC code, SSD =100 cm. The percentage depth dose with or without metal implants were compared. Results The surface absorbed doses on incident plane of stainless steel plate and titanium plate were increased by 19. 6％ and 15.7％ respectively as compared water,the dose influence was less than 1.5％ more than 0. 3 cm outside the incidence plane. The doses on the exit surface of stainless steel plate and titanium plate were lowered by 8. 6％ and 8. 2％ when compared with water, the dose impacts of this places where were from the exit surface of stainless steel plate 、titanium plate more than 1.2 cm,0. 9 cm were less than 1.5％. The surface absorbed doses on incident plane of stainless steel plate were increased by 3.9％ respectively as titanium plate, the dose of the exit surface of stainless steel plate and titanium plate was similar. Conclusions MC method is a fast and accurate calculation method. The influence of metal plate on the radiotherapy dose distribution is significant. Under the such condition, the impact of stainless steel plate is much more than that of titanium alloy plate. Key words: Monte Carlo; Radiation dose; Metal implants

Biomimetic calcium phosphate coating on Ti-7.5Mo alloy for dental application

Titanium and its alloys have been used as bone-replacement implants due to their excellent corrosion resistance and biocompatibility. However, a titanium coating is a bioinert material and cannot bond chemically to bone tissue. The objective of this work was to evaluate the influence of alkaline treatment and heat treatment on the formation of calcium phosphate layer on the surface of a Ti-7.5Mo alloy after soaking in simulated body fluid (SBF). Thirty six titanium alloy plates were assigned into two groups. For group I, samples were immersed in a 5.0-M NaOH aqueous solution at 80°C for 72 h, washed with distilled water and dried at 40°C for 24 h. For group II, after the alkaline treatment, samples were heat-treated at 600°C for 1 h in an electrical furnace in air. Then, all samples were immersed in SBF for 7 or 14 days to allow the formation of a calcium phosphate coating on the surface. The surfaces were characterized using SEM, EDS, AFM and contact angle measurements.

Numerical investigation on the variation of welding stresses after material removal from a thick titanium alloy plate joined by electron beam welding

The stress modification after material removal from a 50 mm thick titanium alloy plate jointed by electron beam welding (EBW) was investigated through the finite element method (FEM). The welding experiment and milling process were carried out to experimentally determine the stresses induced by EBW and their modification after local material removal. The modification of as-welded stresses due to the local material removal method and the whole layer removal method was discussed with the finite element analysis. Investigated results showed that with less materials removal from the top, the stresses on the bottom surface remain almost unchanged; after material removal from the top and bottom part, the transverse stress on the newly-formed surface decreases significantly as compared to the as-welded stresses at the same locations; however, the stress modification only occurs at the material removal region in the case of local region removal method; the longitudinal stress decreases with the whole layer removal method while remains almost unchanged with the local region removal method.

Preparation, release profiles and antibacterial properties of vancomycin-loaded Ca–P coating titanium alloy plate

The aim of the study was to explore the feasibility of the Ca-P coating titanium alloy plate to be used as the vancomycin drug-delivery system by biomimetic coating technology. Through the X-ray diffraction study, the main components of the coatings were identified as octocalcium phosphate. The in vitro vancomycin release, bacteriostasis activity to Staphylococcus aureus (S. aureus), the scanning electron microscope (SEM) image and osteoblast adhesion and proliferation test of vancomycin-loaded Ca-P coating plate were evaluated. The bacteriostatic activity of the vancomycin-loaded Ca-P coating plate showed a continuous drug release and had an inhibitory effect on the growth of the S. aureus. In vitro osteoblast culture results showed that the Ca-P coating plate loaded with or without the vancomycin both obviously promoted the osteoblast attachment. It was suggested that the vancomycin-loaded Ca-P coating may be compounded in the surface of the internal fixators to reduce the incidence of the implant-associated infection.

Design and Manufacturing of a Custom Skull Implant

Problem statement: Cranioplasty is defined as a neurosurgical procedure to cover an injured bone in the skull. This procedure is carried out in order to protect and restore intracranial structures and to restore the appearance and psychological stability of the patient. Advances in medical imaging, such as MRI and CT, have allowed the 3D reconstruction of anatomical structures for several medical applications, including the design of custom-made implants. This study describes the methodology used to design a custom-made cranial implant for a 13-year-old patient who suffered a lesion in the left frontoparietal region of the skull caused by a fall. Approach: The design of the implant was based on the 3D reconstruction of the skull of the patient, obtained by a CT scan, using Rapid Form® 2006. Once the preliminary design was completed, 3D models of the injured region of the skull and of the implant were fabricated in a Rapid Prototyping (RP) machine using Fused Deposition Modeling Technology (FDM) with the purpose of functionally and dimensionally validating the implant. Subsequently, the implant was fabricated using a 1.2-mm-thick Titanium Alloy (Ti6Al4V) plate. Results: The prosthesis was successfully implanted. The surgical time was 85% shorter than that for the same type of surgery in which standard commercial implants and titanium meshes are used. This decrease in surgery time is primarily the result of eliminating the need for trial and error procedures to achieve a good fit for the implant. Finally, the appearance of the patient was restored, allowing the patient to safely perform daily activities. Conclusion: The use of 3D reconstruction techniques from medical images reduces the possibility of errors during surgery, improves fit and provides better implant stability. The use of 3D models designed in RP proved to be an effective practice in the design process.

Interfacial Microstructure and Mechanical Properties of Dissimilar Friction Stir Welds between 6061-T6 Aluminum and Ti-6%Al-4%V Alloys

Friction stir welding (FSW) was performed about AA6061-T6 and Ti-6Al-4V alloy sheets. A unique shaped tool with circular truncated cone of probe was used. Mechanical properties and interfacial microstructure were evaluated using tensile test, hardness test, optical microscopy (OM), scanning electron microscopy (SEM) and scanning transmission electron microscopy (STEM), respectively. Root area of probe in stir zone (SZ) reveals a mixture of finely recrystallized grains of Al and Ti particles pushed away from the base metal by strong stirring of probe. The joint interface of tip area of probe was relatively flat because stirring between aluminum and titanium alloy was not occurred due to the gap of the probe and titanium alloy front. It is considered that the insufficient stirring due to inclined side of the probe was contributed to the decrease of weld strength. After tensile test, fracture surface was analyzed by SEM. In the probe root area, dimples of Al were observed. In the probe tip area, the initial surface of titanium alloy plate was observed. However, in the middle area, similar amount of Ti and Al was detected. As result, it was confirmed that the fracture sequence was very complex and the fracture position was different according to the probe position.

Experimental study on an airway prosthesis made of a new metastable β-type titanium alloy

Surgical treatment of a subglottic stenosis can lead to a cricoid cartilage resection, cervical trachea resection, or both that has to be reconstructed with an artificial prosthesis. However, there is at present no standard treatment in the numerous reconstruction procedures, and many prostheses encounter inflammatory rejection and mechanical constraint problems. A porous, metastable β-type titanium alloy prosthesis was developed to improve subglottic rehabilitation. We have designed a porous type of airway prosthesis made of porous metastable β-type titanium alloy. We used this prosthesis (20 mm in length) to reconstruct the cricoid cartilage and the first tracheal ring in 10 mongrel dogs and evaluated its efficacy. One dog died of an accident with anesthesia at 1 week, 1 dog died of pneumonia about 1 month after the operation, and 6 dogs were killed between the third and eighth months after the operation. At death, all the prostheses had become completely incorporated into the host tissue. Endoscopic examination showed no airway obstruction for a postoperative period of 3 to 8 months in 8 dogs. Granulation was observed in 4 cases, and the porous, metastable β-type titanium alloy plate was exposed in 1 case, but these dogs were asymptomatic. Light microscopic and electron microscopic analysis showed a normal mucous membrane growth on the surface of the prosthesis and no visible granulation tissue in the reconstructed cricoid and tracheal cavity. This airway prosthesis provided good results in canine cricotracheal reconstruction, and this study presents the possibility of successful reconstruction of the cricoid and trachea with epithelial regeneration.

Crack growth with a part-through process zone in thin plates

A cohesive zone model has been proposed to model crack growth with a part-through process zone in a thin solid. With the solid being modeled in Kirchhoff’s plate theory, the crack with a relatively long, inclined front is modeled as a line discontinuity with a finite cohesive zone within the plate. A cohesive force law is adopted to capture the effect of residual strength and residual rigidity of a plate cross-section gradually cracking through the thickness. It is derived by a plane-strain elasticity analysis of a cross section normal to the part-through crack. It is then applied in the plate formulation of a line crack to simulate its propagation within the plate plane. This model essentially resolves the originally three-dimensional crack problem in two hierarchical steps, i.e., in the thickness and in the in-plane directions. In the present study, the bending case is considered. A boundary element method is applied to numerically derive the cohesive force law and simulate the crack growth in a thin titanium-alloy plate. The computational efficiency of the model is demonstrated. The plate is shown to fracture in a nominally brittle or ductile manner depending on its thickness.

Simulation and Experimental Research of Adaptive Control with Constant Pressure on Large-Scale Titanium Alloy Composite Plates

This paper brings a new method of adaptive control with constant pressure on large-scale surface grinding machine. The existing problem of uneven in the process of abrasive belt grinding on titanium alloy composite plates is solved effectively. And the grinding head and the belt follow the plate surface ups and downs effectively through contacting the workpiece with the constant pressure. Not only did ensure the grinding depth and the size of the titanium alloy plates, but also improved the surface processing quality. After experiment, the satisfactory control effect was obtained. The research results have some practical value on adaptive control theory and industrial practice.

Impact of implanted metal plates on radiation dose distribution in vivo

Objective To investigate the impact of metal plate on radiation dose distribution in surrounding tissues in cadaver specimens.Methods Stainless steel plate, titanium plate, and muscle strip were implanted into the left thigh of a corpse, respectively.All the specimens were irradiated with 6 MV X-ray , SSD = 100 cm.The absorbed dose of surface was measured by thermoluminiscent elements.Results Surface dose distributions differed significantly among the three different materials (F = 57.35, P < 0.01),with the amounts of 1.18 Gy ± 0.04 Gy (stainless steel plate), 1.12 Gy ± 0.04 Gy (titanium plate) and 0.97 Gy ±0.03 Gy (muscle strip), respectively.The surface absorbed doses on incident plane of stainless steel plate and titanium plate were significantly increased by 21.65% and 15.46% respectively as compared with that of muscle strip.The absorbed doses on the exit surface of stainless steel plate, titanium plate and muscle strip were 0.87 Gy ± 0.03 Gy, 0.90 Gy ± 0.02 Gy and 0.95 Gy ± 0.04 Gy, respectively (F =13.37, P <0.01).The doses on the exit surface of stainless steel plate and titanium plate were significantly lowered by 8.42% and 5.26% when compared with that of muscle strip.Using treatment planning system,the differences between dose distribution with and without metal plate were compared.Within 1 cm away from the incident plate, there was an obvious increase in the absorbed dose, while the influence was less than 5% 1cm outside the surface.The effect of dose distribution on exit surface was less than 2%.Conclusions The influence of metal plate on the radiotherapy dose distribution is significant.The deviations ranges from 5% to 29%.Under the same condition, the impact of stainless steel plate is much more than that of titanium alloy plate. Key words: Radiotherapy; Radiation dosage; Metal implants; Cadaver specimen

Numerical Investigation of Residual Stress in Thick Titanium Alloy Plate Joined with Electron Beam Welding

A finite-element (FE) simulation process integrating three dimensional (3D) with two-dimensional (2D) models is introduced to investigate the residual stress of a thick plate with 50-mm thickness welded by an electron beam. A combined heat source is developed by superimposing a conical volume heat source and a uniform surface heat source to simulate the temperature field of the 2D model with a fine mesh, and then the optimal heat source parameters are employed by the elongated heat source for the 3D simulation without trial simulations. The welding residual stress also is investigated with emphasis on the through-thickness stress for the thick plate. Results show that the agreement between simulation and experiment is good with a reasonable degree of accuracy in respect to the residual stress on the top surface and the weld profile. The through-thickness residual stress of the thick plate induced by electron beam welding is distinctly different from that of the arc welding presented in the references.

A study of cyclic fatigue, damage initiation, damage propagation, and fracture of welded titanium alloy plate

In this paper, the influence of test specimen orientation and microstructure on cyclic stress-amplitude controlled fatigue response, damage initiation, damage propagation and fracture behavior of samples taken from a welded plate of titanium alloy is presented and discussed. Test specimens from the chosen alloy were prepared from an as-welded plate of the material with the stress axis both parallel (longitudinal) and perpendicular (transverse) to the deformed (rolling) direction of the plate. The test specimens were cyclically deformed at different values of maximum stress at a constant load ratio of 0.1, and the resultant cycles-to-failure was recorded. The fracture surfaces of the deformed and failed test specimens were examined in a scanning electron microscope to establish the macroscopic fracture mode, the intrinsic features on the fatigue fracture surface and the role of applied stress-microstructural feature interactions in establishing the microscopic mechanisms governing failure.