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Search Results: 1 - 10 of 15170 matches for " Cr-Ni-Mo steel "
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Use of coronary stents – material and biophysical conditions
Z. Paszenda
Journal of Achievements in Materials and Manufacturing Engineering , 2010,
Abstract: Purpose: The paper discusses application issues of using the metallic implants for treatment of the cardiovascular diseases. The analysis of the biophysical conditions of the heart – coronary vessels system has been used to distinguish the tissue environment properties which should be compatible with properties of the metal biomaterial and stent’s surface. On this basis the author presented results of experiments concerning the usefulness of the passive-carbon layer for surface treatment of vascular stents made of stainless steel.Design/methodology/approach: In order to determine the usefulness of the layer for implants in cardiology the following tests were carried out on the layer: structure, thickness, corrosion resistance, electrical properties and biocompatibility in experimental animals. The structure and thickness of the layer were tested in high resolution transmission electron microscope. Corrosion resistance was carried out by recording anodic polarization curves. Methodology of measurements took into consideration both implantation conditions and application of vascular stents. In tests concerning electrical properties of the layer, current-potential as well as capacity-potential characteristics were determined.Findings: The passive-carbon layer of nanocrystlline structure and high smoothness created on coronary stents’ surface fully ensures pitting corrosion resistance in both implantation and application conditions.Research limitations/implications: Deposition of the dielectric carbon layer on coronary stents’ made of stainless steel is effective method of reducing reactivity of their surface in blood environment and blood clotting in consequence.Originality/value: The need to determine the correct quality and properties of coronary stents was indicated. The properties refer to stents’ design, physio-chemical properties of the metallic biomaterial and its surface.
Dynamic Recrystallization of a Cr-Ni-Mo-Cu-Ti-V Precipitation Hardenable Stainless Steel
AMomeni,AShokuhfar,SMAbbasi,
A.Momeni
,A.Shokuhfart,S.M.Abbasi

材料科学技术学报 , 2007,
Abstract: In this research, the dynamic recrystallization (DRX) behavior of an as-cast precipitation hardenable (PH)stainless steel was investigated by conducting hot compression tests at temperatures between 950-1150℃ and under strain rates of 0.001-1 s-1. The flow stress curves show that the DRX is responsible for flow softening during hot compression. The effects of temperature and strain rate on the strain and stress corresponding to peak point (εp and σp) of flow curve were analyzed individually. It is realized that, they increase with strain rate and decrease with temperature. The relationship between Zener-Hollomon parameter (Z) and εp was investigated and the equation of εp=4.3×10-4Z0.14 was proposed. The strain for the maximum rate of DRX (εmax) was determined under different deformation conditions. Therefore, it is realized that it increases with Z parameter and vise versa. On the basis of obtained results, the equation of εmax=9.5× 10-4Z0.12 was proposed.
Mechanical properties and corrosion behaviour of 18Cr-11Ni-2,5Mo cast steel
B. Kalandyk,M. Starowicz
Archives of Foundry Engineering , 2009,
Abstract: The study discusses the effect of variable carbon concentration (0,02; 0,07 and 0,14%) on the mechanical properties and corrosion resistance in 3,0% NaCl solution of 18Cr-11Ni-2,5Mo austenitic cast steel. It has been proved that at the concentration of 0,07%C, products made of the examined cast steel reveal on their surface some symptoms of local corrosion. Carbon concentration raised to 0,14%C results in advanced intercrystalline corrosion and the onset of local corrosion. Carbon concentration increased from 0,02 to 0,14% also results in the tensile strength UTS raised from 487MPa to 579MPa (a nearly 20% increase) with elongation El reduced from 55,3% to 49,6%, and reduction of area RA from 69,3% to 53,4%.
Changes of phase morphology in 29 % Cr-6 %Ni-3 %Mo-3 % Cu steel castings with varied wall thickness
B. Kalandyk,J. Augustyn-Pieni??ek
Archives of Foundry Engineering , 2008,
Abstract: The article discusses thc effect of wall thickness and temperature of solultion treatment on the morphology of phascs prcscnt in castingsmade from 29%Cr-6%Ni-3%Mo-3%Cu saeel. The presence of aciculas precipitates near rhc casting surfacc in as-cns~c ondilin~lw as statcd.Thc precipitates ceased to exist after the solution treatment, while volunle fractiot~ of the alloycd Icrrilc incscascd quilc nhviously.Cornpard with parallel investigations carried out on cast steel heats with lower concentration of Cr (24-25%). il has hccn stancd thathigh concentrations of Cr and Mo favour the occurrence of a brittle phasc a, both in as-cast condition and aftcr sol~~ziolrnc nrmcnt.
Microstructure and Abrasive Wear Resistance of 18Cr-4Ni-2.5Mo Cast Steel
B. Kalandyk
Archives of Foundry Engineering , 2012,
Abstract: An influence of a decreased Cr content on the microstructure of the highly alloyed Cr-Ni cast steel, duplex type, melted under laboratoryconditions, was characterized in the paper. The microstructure investigations were performed in the initial state and after the heat treatment (solution annealing) at 1060 C as well as the phase transformation kinetics at continuous cooling was measured. The wear resistance of the investigated cast steel was tested and compared with the 24%Cr-5%Ni-2.5%Mo cast steel.The Cr content decrease, in ferritic-austenitic cast steels (duplex), from 24-26%Cr to 18% leads to the changes of the castingsmicrostructure and eliminating of a brittle phase. In dependence of the casting cooling rate, apart from ferrite and austenite, also fine martensite precipitates occur in the casting structure. It was shown that the investigated cast steel is characterised by a slightly lower wear resistance than the typical cast steel duplex grades.
The effect of (γ→ α’) phase transformation on microstructure and properties of austenitic Cr-Ni steels
A. Kurc,Z. Stok?osa
Archives of Materials Science and Engineering , 2010,
Abstract: Purpose: The paper presents the results of the investigations concerning the effect of (γ→α’) phase transformation on microstructure, magnetic and mechanical properties of austenitic stainless steel grade X5CrNi18-10.Design/methodology/approach: Light microscope examinations, microhardness measurements and static tensile tests were performed in order to reveal microstructure and changes in mechanical properties. The magnetic properties: relative magnetic permeability μ (Maxwell-Wien bridge) and coercive force Hc (permalloy probe) were measured at room temperature. The analysis of the phase composition was carried out on the basis of X-ray investigations. In the qualitative X-ray analysis the comparative method was applied.Findings: : It was found that the plastic deformation in cold rolling within the range 10-70% of investigated austenitic Cr-Ni steel induced in its structure a phase transformation of paramagnetic austenite into ferromagnetic martensite.Research limitations/implications: The results of the X-ray quantitative analysis allowed to determine the proportional part of martensite phases α` in the structure of investigated steel in the examined range of cold plastic deformation.Practical implications: A wide range of practical applications of austenitic X5CrNi18-10 steel sheets is warranted by both their high corrosion resistance and high plastic properties, especially in the supersaturated state. Besides, a strong correlation was found between the magnetic properties and the (γ→ α’) phase transformation.Originality/value: In the course of deformation, the volume fraction of martensite increased at the expense of the amount of austenite resulting in the hardening of the material. In general, a gradual increase of the yield strength results from the strain hardening of the austenite structure and formation of strain-induced martensite.
Evaluation of cast GX40CrNiSiNb24-24 steel after-service conditions
R. Zapa?a,B. Kalandyk,J. G?ownia
Archives of Foundry Engineering , 2011,
Abstract: In this study, an attempt was made to assess changes in the microstructure of centrifugally cast tubes from GX40CrNiSiNb24-24 steel after a long-term operation under the conditions of a catalytic conversion of methane with steam. Changes in phase morphology occurring as a result of high temperature were identified.
The characteristics of two-phase 22Cr-6Ni-2Mo-1,5Cu cast steel
B. Kalandyk
Archives of Foundry Engineering , 2008,
Abstract: The paper discusses the effect of the casting wall thickness on the segregation of alloying elements in two-phase (F-A) 22Cr-6Ni-2Mo-1,5Cu cast steel. The values of the distribution coefficient k0 for Cr, Mo, Si, and Ni, Mn, Cu in the cast stepped test piece walls of three different thicknesses were determined. After solutioning, the values of Rm, R0,2, A5 and Z were measured in the wall of 45 mm thickness and were compared with the results obtained for austenitic cast steel of 18Cr-9Ni grade. In the examined cast steel also the content of δ ferrite and the value of PREN were determined.
Influence of cold rolling on the corrosion resistance of austenitic steel
A. Kurc,M. Kciuk,M. Basiagaa
Journal of Achievements in Materials and Manufacturing Engineering , 2010,
Abstract: Purpose: The paper analyzes the effects of plastic deformation in cold working process on the corrosion resistance, micro-hardness and mechanical properties of austenitic stainless steel X5CrNi18-10.Design/methodology/approach: Corrosion resistance of X5CrNi18-10 steel was examined using weight and potentiodynamic methods. In the weight method, the specimens were immersed in the prepared solution for 87 days. The evaluation of the corrosion behaviour of investigated steel in the potentiodynamic method was realized by registering of anodic polarization curves. The VoltaLab PGP 201 system for electrochemical tests was applied. The tests were carried out at room temperature in electrolyte simulating artificial sea water (3.5% NaCl). Registering of anodic polarization curves was conducted at the potential rate equal to 1 mV/s. As the reference electrode the saturated calomel electrode (SCE) was applied, the auxiliary electrode was platinum electrode. Mechanical properties were evaluated on the basis of the static tensile and Vickers micro-hardness test. The observations of the surface morphology after corrosive tests were carried out using Scanning Electron Microscope SUPRA 25.Findings: According to the results of potentiodynamic analyses it was found that plastic deformation in a cold working of austenitic steel grade X5CrNi18-10 affected to lower its corrosion resistance in 3.5% NaCl solution, what has an essential meaning in industrial applications of this group of materials.Research limitations/implications: The microscope observations of the surface samples subjected to corrosion resistance test in 3.5% NaCl solution permitted to evaluate types and the rate of corrosion damages.Practical implications: The obtained results can be used for searching the appropriate way of improving the corrosion resistance of a special group of steels.Originality/value: The corrosion behaviour in chloride solution of a Cr-Ni austenitic stainless steel was investigated.
Effect of inoculation on high temperature plastic properties of the centrifugally cast Cr-Ni-Nb steel
G. T?cza,J. G?ownia
Archives of Foundry Engineering , 2008,
Abstract: From the centrifugally cast sleeve segments, in direction parallel to the axis, the specimens for mechanical tests were cut out in a way such as to get in one batch of the specimens a structure composed of columnar crystals and in another batch of the specimens a structure composed of equiaxial crystals. The specimens were subjected to a tensile test at the temperature of 820°C. It has been observed that the two zones of crystals differ quite considerably in the values of elongation, while preserving similar tensile strength levels.
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