Chromium Stainless Steel Research Articles

Would CoCr Rods Provide Better Correctional Forces Than Stainless Steel or Titanium for Rigid Scoliosis Curves?

Comparative in vitro, biomechanical study. Compare the effect of rod curvature and material properties on rod flattening and correctional forces. Traditional methods of correction for large progressive deformities involve 3-dimensional correction, performed with an attempt to reach a balanced correction in all planes, spinal instrumentation, and fusion. Increasing attention to the transverse plane correction has developed after the introduction of segmental pedicle screws into the treatment of idiopathic scoliosis. Approximation of the spine (pedicle screws or hooks) to the rods remains the heart of many deformity procedures. Therefore, it is crucial that the instrumentation used provide and maintain the initial correction of the spinal deformity while minimizing potential intraoperative failures. Two experiments were performed using 80 rods made from 4 different materials namely: stainless steel (SS), titanium (Ti), cobalt chromium (CoCr), and ultrahigh strength stainless steel (UHSS). Half of the rods were contoured to 20 degrees, whereas the reaming contoured to 30 degrees. Half of the rods were approximated to a synthetic spine models to measure the flattening of the rods when approximated to highly rigid spine. The other half was used to measure the correctional forces produced by each rod type and curvature. For the 20-degree pre-bend rods, Ti was the best in maintaining its original shape followed by UHSS, SS, and CoCr of 90%, 77%, 62.5%, and 54.4%, respectively. The 30-degree pre-bend showed exactly a similar trend with 80.7% for Ti, 71% for UHSS, 54.6% for SS, and 48.1% for the CoCr rods. For 30-degree pre-bend CoCr and UHSS rods, the intraoperative reduction forces were almost 42% and 10% higher than the Ti and SS rods, respectively. The correctional force produced by the Ti 30-degree pre-bend rod was approximately 67% that of a CoCr and UHSS rods. CoCr and UHSS rods have the ability to produce the highest correction forces, however, both can plastically deform in a very rigid curves. Therefore, it is critical to have sense of the quality of the bone fixation as well as the curve flexibility when selecting for appropriate rod size material and contouring the rod to the desired shape.

Vacuum brazing of stainless steel with silver binder containing nickel and tin

Testing of brazing properties of silver fillers of the Ag72Cu28, Ag68Cu28Sn4 and Ag65Cu28Sn5Ni2 type for vacuum brazing of chromium–nickel and chromium stainless steels on the basis of the spreading test are discussed. Mechanical properties of welded joints and results of metallographic and structural examination are presented.

High Power Diode Laser-Treated HP-HVOF and Twin Wire Arc-Sprayed Coatings for Fossil Fuel Power Plants

This article deals with high power diode laser (HPDL) surface modification of twin wire arc-sprayed (TWAS) and high pressure high velocity oxy-fuel (HP-HVOF) coatings to combat solid particle erosion occurring in fossil fuel power plants. To overcome solid particle impact wear above 673 K, Cr3C2-NiCr-, Cr3C2-CoNiCrAlY-, and WC-CrC-Ni-based HVOF coatings are used. WC-CoCr-based HVOF coatings are generally used below 673 K. Twin wire arc (TWA) spraying of Tafa 140 MXC and SHS 7170 cored wires is used for a wide range of applications for a temperature up to 1073 K. Laser surface modification of high chromium stainless steels for steam valve components and LPST blades is carried out regularly. TWA spraying using SHS 7170 cored wire, HP-HVOF coating using WC-CoCr powder, Ti6Al4V alloy, and high chromium stainless steels (X20Cr13, AISI 410, X10CrNiMoV1222, 13Cr4Ni, 17Cr4Ni) were selected in the present study. Using robotically controlled parameters, HPDL surface treatments of TWAS-coated high strength X10CrNiMoV1222 stainless steel and HP-HVOF-coated AISI 410 stainless steel samples were carried out and these were compared with HPDL-treated high chromium stainless steels and titanium alloy for high energy particle impact wear (HEPIW) resistance. The HPDL surface treatment of the coatings has improved the HEPIW resistance manifold. The improvement in HPDL-treated stainless steels and titanium alloys is marginal and it is not comparable with that of HPDL-treated coatings. These coatings were also compared with “as-sprayed” coatings for fracture toughness, microhardness, microstructure, and phase analyses. The HEPIW resistance has a strong relationship with the product of fracture toughness and microhardness of the HPDL-treated HP-HVOF and TWAS SHS 7170 coatings. This development opens up a possibility of using HPDL surface treatments in specialized areas where the problem of HEPIW is very severe. The HEPIW resistance of HPDL-treated high chromium stainless steels and titanium alloys, HPDL-treated TWAS SHS 7170 and HP-HVOF coatings, and their micrographs and X-ray diffraction analysis is reported in this article.

Three-dimensional open-cell macroporous iron, chromium and ferritic stainless steel

Open-cell macroporous Fe, Cr and their alloys were prepared by dealloying with a metallic melt. By immersing (Fe, Cr)30Ni70 precursors in a Mg melt, Ni selectively dissolved into the Mg and the remaining components formed a bicontinuous structure. Analyses of the thermal coarsening in the melt reveal that evolution of the porous structure is controlled by interfacial diffusion between the melt and precursor solid. The underlying mechanism for the nanoporous structure formation is therefore the same as that in aqueous solution.

EPMA and EBSD analysis of the chemical and structural changes in 16 wt% chromium stainless steel during deformation

In this study, four AISI 430 (EN 1.4016) steel samples of different initial composition and annealing treatment were submitted to uni-axial tension deformation. The as-supplied and deformed materials were characterized by electron channelling contrast imaging, electron backscatter diffraction and electron probe microanalysis. The results show a clear correlation between chemical composition, annealing treatment and strain level obtained until fracture.

Development and analysis of diffusion bonding techniques for LBE-cooled spallation targets

Spallation sources incorporating solid targets may be driven to utilize liquid metal coolants by neutronics or temperature concerns. If tungsten is chosen as the target material, it will require cladding given its poor performance under irradiation. One option to meet this need are ferritic/martensitic stainless steel alloys. This study investigates possible diffusion bonding techniques suitable to clad tungsten targets with HT9, a high chromium stainless steel familiar to the nuclear industry. A test bonding matrix was performed to identify bonding conditions and process parameters suitable for the three material systems of interest (HT9/Ta, HT9/W, and HT9/HT9). Temperatures of 900 and 1060°C were investigated along with bonding pressures of 7 and 70MPa. A nominal soak time of 3h was used for all tests. Three interlayers were investigated: pure nickel, Ni–6P, and vanadium. Finally, different surface preparation techniques for the tungsten were explored in order to gage their effect on the bond quality. Following joining, the bonds were characterized using an array of microscopy and micromechanical techniques to determine the resulting interface character. The nickel and NiP coatings were found to stabilize austenite at the HT9 surface during bonding, while the vanadium remained generally inert given good solubility in each of the three systems. Intermetallic formation is also a significant concern at elevated bonding temperatures as FeTa, FeW, NiTa, and NiW each rapidly form during interdiffusion. Multiple failures were observed through crack propagation parallel to the interface along the intermetallic phases. Differing contraction rates among the base materials also resulted in brittle fracture within the tungsten during cooling from bonding temperatures. Bonding performed at 900°C under 70MPa for 3h with the inclusion of a vanadium interlayer was found to be superior of the conditions explored in this work.

Adsorption and protein-induced metal release from chromium metal and stainless steel

A research effort is undertaken to understand the mechanism of metal release from, e.g., inhaled metal particles or metal implants in the presence of proteins. The effect of protein adsorption on the metal release process from oxidized chromium metal surfaces and stainless steel surfaces was therefore examined by quartz crystal microbalance with energy dissipation monitoring (QCM-D) and graphite furnace atomic absorption spectroscopy (GFAAS). Differently charged and sized proteins, relevant for the inhalation and dermal exposure route were chosen including human and bovine serum albumin (HSA, BSA), mucin (BSM), and lysozyme (LYS). The results show that all proteins have high affinities for chromium and stainless steel (AISI 316) when deposited from solutions at pH 4 and at pH 7.4 where the protein adsorbed amount was very similar. Adsorption of albumin and mucin was substantially higher at pH 4 compared to pH 7.4 with approximately monolayer coverage at pH 7.4, whereas lysozyme adsorbed in multilayers at both investigated pH. The protein–surface interaction was strong since proteins were irreversibly adsorbed with respect to rinsing. Due to the passive nature of chromium and stainless steel (AISI 316) surfaces, very low metal release concentrations from the QCM metal surfaces in the presence of proteins were obtained on the time scale of the adsorption experiment. Therefore, metal release studies from massive metal sheets in contact with protein solutions were carried out in parallel. The presence of proteins increased the extent of metals released for chromium metal and stainless steel grades of different microstructure and alloy content, all with passive chromium(III)-rich surface oxides, such as QCM (AISI 316), ferritic (AISI 430), austentic (AISI 304, 316L), and duplex (LDX 2205).

A New Resource-Saving, High Chromium and Manganese Super Duplex Stainless Steels 29Cr-12Mn-2Ni-1Mo-xN

A new family of resource-saving, high chromium and manganese super duplex stainless steels (DSSs), with a composition in mass percent, % of Cr 0.29, Mn 0.12, Ni 2.0, Mo 1.0, and N 0.51–0.68, has been developed by examining the effect of N on the microstructure, mechanical properties and corrosion properties. The results show that these alloys have a balanced ferrite-austenite relation. The austenite volume fraction decreases with the solution treatment temperature, but it increases with an increase in N content. The increases in nitrogen enhance the ultimate tensile strength (UTS) and reduce the ductility of the material slightly. The pitting corrosion potential increases first and then decreases with an increase in nitrogen content when the amount of N arrives to 0. 68%. The yield stress and ultimate tensile strength of solution-treated samples were more than 680 and 900 MPa, the elongation of experimental alloys are higher than 30%, respectively, what is more, the pitting potentials were beyond 1100 mV.

Effect of mercury on corrosion in production wells in Gulf of Thailand

The effect of mercury on the corrosion of materials used for tubing in oil and gas production wells was studied. Carbon steel (L80) and 13% chromium stainless steel (13Cr) were selected for study by potentiodynamic polarisation. Simulated produced water, with the composition obtained from the Gulf of Thailand field, was used as a corrosive solution. Temperature kinetically increased the corrosion reaction. Chloride ions and carbon dioxide also enhanced the corrosion. Acidity increased the pitting corrosion of 13Cr and increased the corrosion rate of both 13Cr and L80. A concentration of 3–12 ppm of mercury lowered the current density in the passive region and increased the pitting potential of 13Cr. The corrosion rate of L80 was decreased with small amount of mercury addition. The 13Cr showed lower uniform corrosion rate than the L80 in all conditions of the simulated produced water.

Chemical-state information obtained by AES and XPS from thin oxide layers on duplex stainless steel surfaces

Thin oxide films were produced by the exposure of polished, sputter-cleaned metallic surfaces kept in UHV to several thousands of Langmuirs at 10 −5 mbar oxygen yielding oxide layers of several nanometers. Metallic substrates used were iron, chromium and duplex stainless steel (DSS 2205). AES and XPS profiling analyses were performed. An attempt was made to use certain features observed in the AES spectra, i.e. to correlate Fe and Cr MNN peak shapes with the chemical state of the corresponding element. A similar approach has been tried before and may, when combined with high-lateral-resolution AES, provide small-area chemical-state information. Localized chemical-state information derived from the MNN peak shapes by a Linear Least Squares Fit (LLSF) procedure appeared to match reasonably well with that provided by XPS, which is averaged over approximately 2 mm 2. This is a plausible result for a thin homogeneous layer on a polished substrate.

Effects of Microstructural Evolution and Mechanical Properties on 440C-TiC Composite Steel by HIP Treatment

The aim of this paper is to investigate the effects of HIP treatment on 440C-TiC composite steel. In this study, AISI 440C stainless steel powders were added with different amounts of TiC powders (25, 33 and 40 wt%), the composite materials were sintered at 1473 K, 1573 K, and 1673 K, followed by different pressures of HIP and HIP plus heat treatment. HIP treatments were used 120 and 150 MPa at 1523 K 1 hour. Experimental results showed that the microstructure of matrix had small needle structures after HIP treatment, which were effective in improving the hardness and strength. Furthermore 440C-TiC composite steels which were added with 25wt% TiC powder after 1673 K sintered and high pressure HIP treatments, TiC powders were uniformly dispersed in the high chromium stainless steel matrix were observed and consequently possessed the higher hardness (HRA 85) and highest TRS (1213 MPa).

Study on microstructure of low carbon 12% chromium stainless steel in high temperature heat-affected zone

Coarsening, embrittlement and corrosion sensitization in high temperature heat-affected zone (HTHAZ) are the major problems when low carbon 12% chromium stainless steel is being welded, which induce deterioration of the impact toughness at low temperature and intergranular corrosion resistance. This study investigated the corresponding microstructures in HTHAZ with different chemical compositions and heat inputs through thermal simulation tests. There are several primary conclusions: (1) When ferrite factor (FF) is above 9.0, the microstructure in HTHAZ is fully ferrite or a small amount of martensite net likely distributing along delta ferrite grain boundaries. On the other hand, if FF is below 9.0, the martensite content increases with the decreasing of FF. (2) Heat input influences the microstructure of high FF steel in HTHAZ. The martensite content and its distribution of low FF steel are not sensitive to heat inputs, but the grain size grows up with the increase of heat inputs. (3) The coarse Ti-rich particles in low FF steels containing Ti can promote intragranular austenite formation inside delta ferrite resulting in packet morphology of martensite. On the other hand, martensite of low FF steels only stabilized with Nb is characterized by grain boundary allotriomorphs, Widmanstätten structures and secondary sawteeth. This martensite reticularly distributes along ferrite grain boundaries.

CARPENTER CTS-40CP ALLOY

Abstract Carpenter CTS-40CP alloy is a powder metallurgy, high-carbon chromium stainless steel designed to provide stainless properties with maximum hardness. CTS alloys are used for many blade applications. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, joining, and powder metal forms. Filing Code: SS-1055. Producer or source: Carpenter Specialty Alloys.

Corrosion of nickel–chromium alloys, stainless steel and niobium at supercritical water oxidation conditions

Results of immersion tests of UNS N06625 (alloy 625), UNS S31609 (alloy 316 L), Ni–20Cr alloy and Nb coupons exposed to oxygenated ammoniacal sulphate solution at supercritical water oxidation (SCWO) conditions are presented. The corrosion behavior of the alloy 316 L (UNS S31603) SCWO reactor tubing is also presented under the same conditions. Immersion coupons corroded at a rate not exceeding 40 mm yr −1 while the reactor tube itself corroded at a rate of between 160–1500 mm yr −1, depending on which length of the reactor is considered to have corroded. Morphological and chemical analysis of the oxides present on the coupon samples suggest that iron oxides, which had initially precipitated on the corroding alloy 316 tube surface, were removed by heat flux-driven fluid mechanical action and transported through the reactor where they deposited on the coupons. Niobium was resistant to corrosion at the tested conditions.

Comparative analysis of microstructure and fracture surfaces of blade roots

Samples of chromium stainless steel were loaded to investigate fatigue crack growth in roots of steam turbine blades. Images of the material microstructure and fracture surfaces were subjected to textural image analysis. The main steps were normalization, enhancement of fiber structures and 2D Fourier transforms. By means of analysis of spectra in the space of periods, characteristic dimensions of both image sets were investigated. The locations of three peaks of spectral functions are very close in both image sets. It may be concluded that the material microstructure is projected onto the morphology of fracture surfaces much more than was expected.

Investigation of thin-oxide-free protective coatings on chromium and 316L stainless steel formed by treatment with etidronic acid

In this article, the authors report how thin (10nm or less) oxide-free phosphorus containing films can be formed on chromium and stainless steel on treatment with an organophosphorus acid (etidronic acid) using an anaerobic cell and a “bench” treatment. Core level and valence band x-ray photoelectron spectroscopy were used to study the films formed. Compositional variations were interpreted through the use of band structure and X-alpha calculations. The chromium study indicates that the etidronate at least partially decomposed to form phosphate. Some phosphide was observed for the bench treatment. Polished 316L chromium containing stainless steel treated in 3M etidronic acid formed a thin phosphate containing film when using the bench treatment, but a film characteristic of etidronate when the anaerobic cell was used. Film changes during air exposure and exposure to 1M sodium chloride solution showed decomposition, the most resistant film being that of the etidronate on stainless steel. This thin etidronate film result shows that oxide-free etidronate films can be formed on stainless steel and these films have corrosion inhibition properties, which may find application in implant fabrication.

高減衰鋼片の超音波探傷技術

Various nondestructive testing have been applied for steel products in manufacturing processes. Ultrasonic inspection is an important method to evaluate inclusions in rolled billets. Conventional ultrasonic transducer with a flat piezoelectric element is used for the inspection. However, ability of inspection for a part of chromium stainless steel billets with coarse grain is insufficient with comparison to the ability for carbon steel billet. This paper describes a result of development of new ultrasonic transducers for the billets with coarse grain. Numerical analysis with finite element method was carried out to make sure a best frequency and wave shape. Two transducers are designed and confirmed advantages over the conventional transducers.

Corrosion-induced release of the main alloying constituents of manganese–chromium stainless steels in different media

The main focus of this paper is the assessment of release rates of chromium, nickel, iron and manganese from manganese-chromium stainless steel grades of low nickel content. The manganese content varied between 9.7 and 1.5 wt% and the corresponding nickel content between 1 and 5 wt%. All grades were exposed to artificial rain and two were immersed in a synthetic body fluid of similar pH but of different composition and exposure conditions. Surface compositional studies were performed using X-ray photoelectron spectroscopy (XPS) in parallel to correlate the metal release process with changes in surface oxide properties. All grades, independent of media, revealed a time-dependent metal release process with a preferential low release of iron and manganese compared to nickel and chromium while the chromium content of the surface oxide increased slightly. Manganese was detected in the surface oxide of all grades, except the grade of the lowest manganese bulk content. No nickel was observed in the outermost surface oxide. Stainless steel grades of the lowest chromium content (approximately 16 wt%) and highest manganese content (approximately 7-9 wt%), released the highest quantity of alloy constituents in total, and vice versa. No correlation was observed between the release rate of manganese and the alloy composition. Released main alloy constituents were neither proportional to the bulk alloy composition nor to the surface oxide composition.

Relationship among the rolling thickness and the formability properties in a cold rolled 10.5% chromium ferritic stainless steel

The mechanical properties of a 10.5% chromium stainless steel strip have been determined as a function of the cold rolling reduction ratio. The best formability properties after annealing are associated to the higher cold deformation. This is a consequence of the texture development and through thickness homogeneity. The recristallized grains mis-orientation has been studied with the CSL approach and the coincidence index.

Influence of Nb Stabilization on the Recovery and Recrystallization Kinetics of a Ferritic Stainless Steel: Consequences on Magnetic Losses

Softening kinetics of two 17% chromium (Cr) stainless steel grades that differ in niobium (Nb) content are compared. In the experiments, we observed that a low Nb stabilization makes recrystallization nucleation much faster and prevents incomplete recrystallization. A qualitative interpretation, based on interaction with precipitates, is proposed and explains the main features of the softening kinetics as well as the microstructures obtained. For the Nb stabilized grade, magnetic losses were measured in the deformed state and after recrystallization. Above a specific magnetizing frequency, the deformed state led to smaller losses than the recrystallized state. These results are believed to be attributed to a grain size effect.