Effect Of Hydrostatic Extrusion Research Articles

Effect of Grain Refinement on the Corrosion Resistance of 316L Stainless Steel.

The effect of hydrostatic extrusion (HE) on the microstructure, uniform corrosion, and susceptibility to a localized attack of 316L stainless steel was studied. Both qualitative and quantitative analyses of inclusions before and after HE were carried out. The multiplication of non-metallic inclusions after HE lowered the stability of the passive film over a broad range of pH, while refinement of the matrix had a minor effect on it. The refined materials were prone to metastable pitting, but their pitting corrosion resistance was improved.

Effect of hydrostatic extrusion on structural and magnetic properties of polycrystalline Dy

Effect of hydrostatic extrusion on structural and magnetic properties of polycrystalline Dy

Microstructural analysis of the 〈111〉 and 〈110〉 nickel single crystals subjected to severe plastic deformation by hydroextrusion

The effect of hydrostatic extrusion (HE) on the microstructure and crystalline orientation of the 〈111〉 and 〈110〉 nickel single crystals was examined. The crystals were deformed by two-step hydrostatic extrusion to achieve the true strain εr=2.4. After the extrusion the samples had the form of cylindrical rods. The mechanical properties of the extruded samples (expressed in terms of their microhardness) were compared with the mechanical properties of ultra-fine grained nickel obtained by subjecting polycrystalline nickel to HE. The microhardness of the two deformed crystals appeared to be similar. The microstructure of the samples and the orientation evolution were examined using transmission electron microscopy (TEM), electron back scattered diffraction (EBSD) and X-Ray diffraction (XRD).Both the deformed crystals had an inhomogeneous ultra-fine-grained structure (as observed by TEM). The average grain diameter was 300nm. The majority of the grain boundaries had high angle disorientations (EBSD).In both the deformed samples the predominating orientation was 〈111〉 (XRD). In the 〈111〉 oriented crystal 95% of the initial orientation was preserved whereas in the 〈110〉 oriented crystal the initial orientation was predominantly transformed into 〈111〉 and 〈100〉.

Effect of Hydrostatic Extrusion with Back Pressure on Mechanical Properties of Grey and Nodular Cast Irons

Effect of Hydrostatic Extrusion with Back Pressure on Mechanical Properties of Grey and Nodular Cast Irons

Structure and properties of hydrostatically extruded commercially pure titanium

The effect of hydrostatic extrusion on the structure and mechanical properties of commercially pure titanium was investigated at 20 °C, 350 °C, and 450 °C, up to the true strain of e = 2. At 20 °C extrusion to e = 1.8 resulted in the formation of a lamellar-type microstructure with fragments of about 100 nm within the laths. Higher deformation temperatures lead to the formation of mixed microstructures consisting of packs of lamellae alternating with fine-grained areas. Hydrostatic extrusion results in a remarkable increase in the strength of titanium. The ultimate tensile strength of titanium extruded at 20 °C and 350 °C was 1080 and 765 MPa, respectively. The strength and elongation at the fracture can be controlled by varying the temperature of the extruded billet. The optimal deformation parameters for various applications are proposed.

Effect of Hydrostatic Extrusion on the Corrosion Resistance of Type 316 Stainless Steel

Abstract The corrosion resistance of Type 316 (UNS S31600) austenitic stainless steel in an aggressive environment containing Cl− ions in the as-received state and after nanostructuralization caused by severe plastic deformation by hydrostatic extrusion (HE) was investigated. Transmission electron microscopy (TEM) was used to examine the structural changes introduced by the HE process. The effects of the surface oxide film on the corrosion resistance of Type 316 stainless steel in a borate buffer + 0.1 M sodium chloride (NaCl) solution and in a saline solution of 0.15 M NaCl were investigated using potentiodynamic polarization. Surface analytical techniques such as scanning electron microscopy (SEM) and Auger electron spectroscopy (AES) were used to characterize the morphology and chemistry of the surface before and after HE.

Effect of hydrostatic extrusion on passivity breakdown on 303 austenitic stainless steel in chloride solution

The stability of the passive film formed on austenitic 303 stainless steel in the as-received state and after severe plastic deformation by hydrostatic extrusion (HE) leading to nanostructurization was investigated in an aggressive environment containing Cl− ions by anodic polarization. Transmission electron microscopy (TEM) and stereological image analysis were used to examine structural changes introduced by HE. Surface analytical techniques such as light microscopy, scanning electron microscopy, Auger electron spectroscopy (AES), and scanning Auger microscopy (SAM) were used to characterize the morphology, grain size, and chemistry of the surface, including local characterization of nonmetallic inclusions and their surface before and after HE. SAM analysis revealed discontinuities of the passive oxide film on MnS inclusions. TEM and scanning transmission electron microscopy examinations confirm a drastic reduction of grain size accompanied by a distinct refinement of the size of sulfide inclusions in the HE matrix. These changes in the HE 303 stainless steel are apparently responsible for its reduced pitting resistance compared to the as-received material.

Effect of hydrostatic extrusion at 600–700 °C on the structure and properties of Ti–6Al–4V alloy

The effect of hydrostatic extrusion in the range 600–700 °C on the structure and mechanical properties of Ti–6Al–4V titanium alloy with a lamellar microstructure is reported in the paper. Extrusion at 600 °C resulted in the formation of a heterogeneous microstructure consisting of submicrocrystalline grains of size about 0.2 μm and thick lamellae aligned with the extrusion axis. An increase of the extrusion temperature increased the volume fraction of the globularized structure and the grain size. The hydrostatic extrusion leads to a remarkable increase in the strength of the alloy. The ultimate tensile strength of a sample extruded at 600 °C to a true deformation of e = 1.4 was 1530 MPa.

The effect of hydrostatic extrusion on resistance of 316 austenitic stainless steel to pit nucleation

The resistance to pit nucleation of an austenitic 316 stainless steel was investigated in an aggressive environment containing Cl − ions in the as-received state, and after a heavy deformation by hydrostatic extrusion (HE) leading to nanostructurisation. XRD and TEM were used to examine structural changes introduced by HE treatment. The corrosion resistance of 316 stainless steel was investigated by potentiodynamic polarization in a borate buffer + 0.1 M NaCl. The results show that the HE processed material exhibits an extended stable passivity region by about 0.4 V or more, as compared to that of the as-received one.

Damage accumulation and mechanical properties of particle-reinforced metal–matrix composites during hydrostatic extrusion

The effects of hydrostatic extrusion on particle cracking and on the subsequent tensile properties of some prototypical particle-reinforced metal–matrix composites are investigated. In most cases, tensile failure occurs through a plastic instability in accordance with the Considere criterion for necking. The corresponding failure strain is therefore dictated by the global flow and hardening characteristics of the composites, as influenced by the intrinsic flow properties of the matrix as well as the extent and rate of particle cracking. Such cracking leads to significant reductions in the hardening rate and thus causes a reduction in the failure strain relative to that of the neat matrix alloy. Extrusion prior to tensile testing has the effect of saturating the flow stress of the matrix and limiting the tensile ductility to low values, largely because of the very low hardening rate of the matrix. Particle cracking during extrusion causes a further reduction in ductility. The dominant role of the matrix hardening is demonstrated through re-tempering treatments of extruded billets prior to tensile testing. A micromechanical model of particle cracking is developed, taking into account the effects of both the hydrostatic and the deviatoric stress components in axisymmetric loadings. The model is used to rationalize the observed trends in damage accumulation with particle content, particle type, and loading configuration (tension vs. extrusion).

Effects of hydrostatic extrusion on the mechanical and thermal properties of polypropylene

The structure change in spherulites for hydrostatically extruded polypropylene (PP) was studied by the use of internal friction measurements and thermophotometry tests. The onset temperature of the β-loss peak of the PP sample decreases with increasing reduction in area, R. For the extrudates below R=50%, the peak temperature of α-loss shifts to lower temperature. The α and β absorptions for the extrudates up to R=50% become broad and overlap with each other. The intensity of the β-loss peak, Δmax, is maximum for the extrudate with R=50%. The results of tan δ, damping, and the intensity of the β-loss peak indicate that the mechanism of molecular chain deformation is divided into two stages, below and above R=50%. The results are due to spherulitic changes, i.e. the shape of spherulites changed from spherical to elliptical in the extrudates above R=50% and the spherulite with R=50% changed from coarse structure to a finer one by the imposition of hydrostatic pressure.

Effect of hydrostatic extrusion on the wear resistance of R6M5 cutters

Preliminary treatment of rods, including hydrostatic extrusion and tempering at 500°, doubles the tool life of cutters.

Mechanical Testing and Structural Characterization of Hydrostatically Extruded Polymers. I. Effects of Hydrostatic Extrusion on Subsequent Mechanical Behavior

Crystalline and amorphous polymers were hydrostatically extruded at room temperature with pressures up to 4 kilobars. Polymers studied include polyethylene, polypropylene, nylon, polyacetal, polyvinylchloride, ABS-co-polymer, polymethylmethacrylate and polycarbonate. Within the range of reduction percentages studied, 20-85%, the extention showed higher flow stress and lower elongation than the starting materials except PMMA: Fourfold increase in elongation with essentially unchanged flow stress was observed with the amorphous polymers. Dimensional stability of the crystalline extrusion at room temperature and also at 100°C decreased with an increasing reduction percentage and reached a minimum at 60% reduction, followed by an increase with higher reduction. On the other hand, with the amorphous polymers, the higher the reduction percentage, the poorer the dimensional stability. A linear relation was established between the extrusion pressure and the extrusion ratio. The polymers were also tested for compression, bending, specific gravity and hardnees, and correlation among the test results was discussed under assumption of a possible structural change due to hydrostatc extrusion.

Effect of hydrostatic extrusion on mechanical properties of trip steels

1. Hydrostatic extrusion increases the deformability of TRIP steels, which simplifies the treatment but retains the good combination of mechanical properties. 2. Good mechanical properties of TRIP steels are obtained by warm hydrostatic extrusion (250°), ensuring large reductions (75%): σ0.2=180 kg/mm2, σb=200 kg/mm2, δ=10%. Hydrostatic extrusion at room temperature permits reductions of only 44%, which leads to lower strength characteristics —σ0.2=150 kg/mm2, σb=174 kg/mm2 — although δ=34%. 3. Tempering of hydrostatically extruded TRIP steels leads to a substantial improvement in the strength and ductile characteristics. The best combination of properties is obtained with tempering at 550° after warm hydrostatic extrusion with 75% reduction: σ0.2=190 kg/mm2, σb=220 kg/mm2, δ=35%. 4. Stress—strain diagrams were analyzed and the effect of the martensitic transformation on the mechanical properties of TRIP steels was demonstrated.

Mechanical Testing and Structure Characterization of Hydrostatically Extruded Plastics : 1st Report, Effects of Hydrostatic Extrusion on Subsequent Mechanical Behavior

Mechanical Testing and Structure Characterization of Hydrostatically Extruded Plastics : 1st Report, Effects of Hydrostatic Extrusion on Subsequent Mechanical Behavior

Effect of hydrostatic extrusion on the properties of structural steels

Effect of hydrostatic extrusion on the properties of structural steels

Effect of hydrostatic extrusion on the composition and properties of Nb3Sn compounds

Effect of hydrostatic extrusion on the composition and properties of Nb3Sn compounds