Non-magnetic Stainless Steel Research Articles

Static strain aging in cold rolled stable austenitic stainless steel

The effects of cold rolling reduction ratio, initial grain size, and aging condition (temperature and time) on static strain aging (SSA) behavior were systematically investigated in stable austenitic stainless steel. The aging treatment increased the yield strength (YS) and ultimate tensile strength (UTS), and the SSA effect was more pronounced at higher reduction ratio or smaller initial grain size. The SSA effect occurred in the temperature range of 400∼600 °C, where the accumulated dislocations remained in the form of wavy boundaries. Quantifying the dislocation density clearly showed that the SSA effect was directly related to the dislocation density. The volume shrinkage and increase in thermal expansion coefficient by aging treatment suggested the correlation between SSA behavior and atomic distribution changes. 3D atom probe tomography analysis clearly exhibited the clustering and segregation of solute C atoms during aging treatment. These results suggest that the SSA effect may be attributed to the interaction between solute C atoms and dislocations. Through grain refinement and optimal aging treatment at 500 °C for 1 h, the YS and UTS were significantly increased by 319 MPa and 230 MPa, respectively, to obtain a non-magnetic stainless steel with ultrahigh YS of up to 1600 MPa.

Study of Electromagnetic Shielding Properties of Composites Based on Glass Fiber Metallized with Metal Films

The article presents the results of an investigation of composites based on manufactured samples of fiberglass metalized with a submicron film made of brass, neusilber and non-magnetic SS304 stainless steel. It was found that, due to their characteristics, the samples of metallized fiberglass are an effective electromagnetic wave-absorbing filler for various building and construction materials; The developed metallized fiberglass samples are also useful for the creation of EMI-shielding building materials for protection from microwave radiation. With an increase in the proportion of metalized glass fiber, the electromagnetic shielding of the studied composites increases systematically. It is determined that at a concentration of 5 wt.% brass-metallized glass fiber, a test composite material with a thickness of 250 mm is able to shield up to 13.7 and 21.2 dB in the 4G and 5G ranges of cellular communication electromagnetic waves, respectively.

Experimental Analysis of Synergetic Effect of Part-Cooled Exhaust Gas Recirculation on Magnetic Field-Assisted Combustion of Liquefied Petroleum Gas

Magnetic field-assisted combustion has been under the focus of research for the last three decades around the globe. The effects of strong uniform and gradient magnetic fields on flame development, behaviour and propagation have been studied, and their applications have been experimented on Internal Combustion Engines. The present work investigates the synergetic effect of part-cooled EGR on the magnetic field-assisted combustion of liquefied petroleum gas in a multicylinder MPFI spark-ignited engine modified for neat LPG operation. Sintered neo-delta magnets with radial magnetization pattern of four different magnetic intensities (0G, 3200G, 4800G and 6400G) are fastened to the fuel line near to the gas injector with a non-magnetic stainless steel integument to prevent any loss of magnetic intensities during the operation. A portion of the exhaust gas is channelled to an intercooler and an optimum percentage of the partially cooled gases are inducted into the inlet manifold for combustion. The experimental study concludes that the optimum flow rate of part-cooled EGR acts synergistically with the applied magnetic fields to enhance the combustion characteristics of LPG emanating an improved fuel economy of 13.8% and brake thermal efficiency of 3.9%. The increased emission of oxides of Nitrogen which is the major setback of LPG combustion can be addressed through the combined effect of part-cooled EGR and magnetic field-assisted combustion. Moreover, the reduction in stability of combustion through the recirculation of exhaust can also be balanced by the applied magnetic field.

Evaluation of the Microstructure and Performance of Fe-21Cr-15Ni-6Mn-Nb Nonmagnetic Stainless Steel Welded Joints

In the present study, double-sided gas shield welding (GSW), in a single pass, was applied to Fe-21Cr-15Ni-6Mn-Nb nonmagnetic stainless steel plate. The microstructure and performance of the welded joint were investigated via microstructural and phase analysis, mechanical testing and magnetic analysis. The results showed a satisfactory micrographic appearance with full penetration, and no solidification defects observed in the welded joint, which showed typical epitaxial growth characteristics in the welding solidification. Slight grain growth, with an average size of ~ 18.9 μm, occurred in the heat-affected zone (HAZ). The primary dendrite arms, on both sides of welding joint, grew along the direction of the temperature gradient and met at the centerline of the weld with no parting microstructure in evidence. The secondary dendrite arm spacing was stable in all parts of the weld zone (WZ). The hardness of the weld zone was higher than that of the HAZ and the base metal (BM), with the lowest hardness occurring in the HAZ. The results of tensile testing showed a higher strength of the welded metal (WM) compared to the BM, and a good strength-ductility balance of the welded joint. The impact energy of the HAZ was higher than that of the WZ, corresponding to 60.5 J at room temperature and 52.7 J at − 196 °C. Microvoid coalescence, concurrent with crack propagation along the direction of the long axis of the dendritic sub-grains, was observed during plastic deformation in the WZ. Additionally, the excellent paramagnetic characteristics of the welded specimens were revealed.

Development of two directional beam steering ECH/CD launcher for JT-60SA

Developments of a two directional beam steering electron cyclotron heating/current drive launcher for JT-60SA have been progressed based on a linear motion antenna concept. A full-scale (˜7 m) mock-up of the mirror steering structure with two kinds of bellows structures and an in-vessel support structure has been fabricated and tested in vacuum successfully. The support structure consists of a pair of angular ball bearings made of Si3N4 for rotational motion and a linear guide assembled by a rail and a housing made of non-magnetic stainless steel and Si3N4 balls. Solid lubricant has been used for the linear guide and it results in the improvement of the life time by a factor greater than 10 with respect to the case without lubricant. Considering that the mock-up test results satisfied the requirements for the bellows and support structures (reliable 40 cm linear movement, 105 cycles and angular rotation 30°, 104 cycles), the final design of the launcher is underway targeting the start of its fabrication.

Microstructure characterisation of Fe–21Cr–15Ni–Nb–V non-magnetic austenitic stainless steel during hot deformation

ABSTRACTHot deformation behaviour of Fe–21Cr–15Ni–Nb–V stainless steel was investigated by isothermal compression in the temperature range of 950–1150°C with a strain rate of 0.01–10 s−1. The results showed that complete recrystallisation occurred beyond 1050°C, resulting from the pinning effect of (Nb, V)(C, N). The nucleation of dynamic recrystallisation (DRX) was performed by the bulging, sub-grain swallowing and twinning mechanism. With increasing strain rate, new twinning was transformed into the Σ3 regeneration mechanism in the partial DRX region, while an opposite transformation was observed in the complete DRX region. In the partial recrystallisation region, grain rotation resulted in the formation of 110 orientation. In the complete recrystallisation region, the texture tended to distribute randomly at a high strain rate, and the grain growth was accompanied by the emergence of stable 100 orientation.

Grain character and mechanical properties of Fe-21Cr-15Ni-6Mn-Nb non-magnetic stainless steel after solution treatment

A systematic investigation on grain growth behavior, grain boundary character distribution and mechanical properties of Fe-21Cr-15Ni-6Mn-Nb non-magnetic stainless steel was performed after solution treatment in temperature range of 1100–1200 °C with various durations. The results showed the hot-rolled plate still maintained fine microstructure with the grain size range of 11.5–19.6 µm after solution treatment. A Nb(C, N) drag mechanism concurrent with a restraining effect of Σ3n boundaries during solution treatment resulted in a slow kinetics with grain growth exponent n of ~ 4. The proliferation mechanism of Σ3n boundaries mainly varied from Σ3 regeneration to new twinning accompanied by grain growth. Twin boundary has an effective strengthening role like a grain boundary. The YS, UTS and elongation of solution-treated plate was above 634.0 MPa, 838.9 MPa, 45.3％, respectively, which were superior to the conventional austenitic stainless steel. The Hall-Petch relationship was determined well between the grain size under the condition of either including or excluding twin boundaries and tensile results. An inherent relationship between k′ and k (k′ and k correspond to the circumstance of including and excluding twin boundaries, respectively), was expressed by k′=1.52037+1.67168k.

Magnetic field inhomogeneities due to CO2 incubator shelves: a source of experimental confounding and variability?

A thorough assessment of the static magnetic field (SMF) inside a CO2 incubator allowed us to identify non-negligible inhomogeneities close to the floor, ceiling, walls and the door. Given that incubator's shelves are made of a non-magnetic stainless steel alloy, we did not expect any important effect of them on the SMF. Surprisingly, we did find relatively strong distortion of the SMF due to shelves. Indeed, our high-resolution maps of the SMF revealed that distortion is such that field intensities differing by a factor of up to 36 were measured on the surface of the shelf at locations only few millimetres apart from each other. Furthermore, the most intense of these fields was around five times greater than the ones found inside the incubator (without the metallic shelves in), while the lowest one was around 10 times lower, reaching the so-called hypomagnetic field range. Our findings, together with a survey of the literature on biological effects of hypomagnetic fields, soundly support the idea that SMF inhomogeneities inside incubators, especially due to shelves' holes, are a potential source of confounding and variability in experiments with cell cultures kept in an incubator.

Compositionally graded magnetic-nonmagnetic bimetallic structure using laser engineered net shaping

Fabrication of compositionally-graded magnetic-nonmagnetic bimetallic structures was successfully completed using a laser engineered net shaping (LENS™) system. A graded magnetic functionality was implemented by directly transitioning from non-magnetic austenitic stainless steel 316 (SS316) to magnetic ferritic stainless steel 430 (SS430) in a single structure. LENS™ additive manufacturing utilizes a high-powered laser to continuously melt and bond metallic powder in successive layers to create the 3D structure. Microstructures revealed a preferred grain growth direction at the interfaces of the deposited layers. Micro-hardness values across the part’s cross-section exhibited a smooth transition from the highest value of 266 ± 4 HV in the SS430 region to the lowest value at the SS316 substrate of 174 ± 3 HV. Magnetic functionality was observed on the SS430 side of the bimetallic structure, showing how LENS™ can additively combine materials of varying compositions for location-specific functionality.

Design and Fabrication of a Planar Helix Slow-Wave Structure for $C/X$ -Band TWT

This paper presents the design and fabrication of a planar helix slow-wave structure (SWS) with straight-edge connections at ${C}/{X}$ -band frequencies. Besides RF performance, various issues such as vacuum compatibility of materials as well as ease and accuracy of assembly techniques are specially emphasized. The basic SWS is fabricated on a pair of alumina substrates using printed-circuit techniques and is fixed in a nonmagnetic stainless steel housing. The SWS is fed with coaxial couplers. Simulated and measured cold-test parameters of the fabricated structure are presented, showing a wide −10-dB bandwidth in the 6–9-GHz frequency range. The measured phase velocity and circuit loss match the simulated values well. The coupling impedance and hot-test parameters are also studied using simulations. It is shown that the proposed structure is able to provide a saturation output power of 100 W in the frequency range of 6–8 GHz. Such a structure is an attractive candidate for low-cost ${C}$ - and ${X}$ -band traveling-wave tubes fabricated using printed-circuit techniques.

URANUS B64

Abstract Uranus B64 is a nonmagnetic high strength stainless steel. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as fracture toughness and fatigue. It also includes information on low temperature performance, corrosion resistance, and surface qualities as well as forming, heat treating, and joining. Filing Code: SS-1253. Producer or source: Industeel USA, LLC. See also Alloy Digest SS-1218, July 2015.

Vessel eddy current characteristics in SST-1 tokamak

Eddy current distribution in the vacuum vessel of the Steady state superconducting (SST-1) tokamak has been determined from the experimental data obtained using an array of internal voltage loops (flux loop) installed inside the vacuum vessel. A simple circuit model has been employed. The model takes into account the geometric and constructional features of SST-1 vacuum vessel. SST-1 vacuum vessel is a modified ‘D’ shaped vessel having major axis of 1.285m and minor axis of 0.81m and has been manufactured from non-magnetic stainless steel. The Plasma facing components installed inside the vacuum vessel are graphite blocks mounted on Copper Chromium Zirconium (CuCrZr) heat sink plates on inconel supports. During discharge of the central solenoid, eddy currents get generated in the vacuum vessel and passive supports on it. These eddy currents influence the early magnetic NULL dynamics and plasma break-down and start-up characteristics. The computed results obtained from the model have been benchmarked against experimental data obtained in large number of SST-1 plasma shots. The results are in good agreement. Once bench marked, the calculated eddy current based on flux loop signal and circuit equation model has been extended to the reconstruction of the overall B- field contours of SST-1 tokamak in the vessel region. A comparison of the field lines with and without the plasma column in identical conditions of the central solenoid and equilibrium field profiles has also been done with an aim to quantify the diagnostics responses in vacuum shots.

Lift-Off Point of Intersection Feature in Transient Eddy-Current Oscillations Method to Detect Thickness Variation in Stainless Steel

Detection of corrosion and measurement of the thickness of stainless steel in industrial structures, such as pipelines, has been an important issue to avoid unwanted leakages. A recently proposed transient eddy-current oscillations (TECO) method has been used in this paper to measure thickness in non-magnetic stainless steel. The TECO method works based on the electromagnetic induction principle, as the conventional eddy-current testing method. An inductor (excitation coil) connected in parallel with a capacitor to generate damped oscillations is used to induce eddy currents into the test material beneath the coil. A Hall sensor, which is fixed at the bottom side and at the axial center of the excitation coil, detects the resultant magnetic field due to the induced eddy currents. Experiments were performed on the stainless steel specimens, having different thicknesses to test the potential of the TECO method. The results were analyzed using the fast Fourier transform. This paper proposes a lift-off point of intersection in the frequency domain that can be used to eliminate the false indications due to the lift-off variations during the thickness measurement of the test material. The results reveal that the proposed method can be applied to detect the thickness variations in metal structures covered with non-conductive paints or insulation coatings.

Research on Nondestructive Examination of Jacket Sections for CFETR Central Solenoid Model Coil

The central solenoid model coil (CSMC) is a large superconducting “model” coil, which is responsible for developing and verifying the key manufacturing methods of the China Fusion Engineering Test Reactor. Therefore, all subcomponents have very strict requirements, including the conductors which are cable-in-conduit conductor (CICC) type. The jacket section as an important component of the CSMC CICC is circular-in-square type, which is nonmagnetic stainless steel. Severe requirements not only high mechanical performances but also the size of initial defects in the jacket section were specified. Based on the linear elastic fracture mechanics, maximum acceptable defect sizes inside the jacket material have been estimated. Phased array ultrasonic test (PAUT) supplemented with eddy current test (ECT) were studied and developed for nondestructive examination. The defects inside the jacket section can be detected by PAUT with 11 runs by 4 probes. The defects on inner surfaces can be detected by ECT. Focal laws on PAUT and parameters of ECT are also discussed in this paper.

NSSMC NAR-30

Abstract UNSSMC NAR-305B is a nonmagnetic heat and corrosion-resistant austenitic stainless steel with high silicon. This datasheet provides information on composition, hardness, and tensile properties. It also includes information on corrosion resistance as well as forming. Filing Code: SS-1226. Producer or source: Nippon Steel and Sumitomo Metal Corporation.

NSSMC NAR-305G

Abstract NSSMC NAR-305G is a nonmagnetic austenitic stainless steel even when cold worked. This datasheet provides information on composition, hardness, and tensile properties. It also includes information on forming. Filing Code: SS-1221. Producer or source: Nippon Steel and Sumitomo Metal Corporation.

URANUS B64

Abstract Uranus B64 is a pitting resistant, high-strength nonmagnetic stainless steel. This datasheet provides information on composition, physical properties, elasticity, and tensile properties as well as fracture toughness and fatigue. It also includes information on low temperature performance and corrosion resistance as well as forming, heat treating, joining, and surface treatment. Filing Code: SS-1218. Producer or source: Industeel USA, LLC. See also Alloy Digest SS-1253, October 2016.

Suppression of shunting current in a magnetically insulated coaxial vacuum diode

Real-time investigations of the dynamics of explosive electron emission from a high-voltage cathode holder made of nonmagnetic stainless steel in a magnetically insulated coaxial vacuum diode have been performed. It has been shown that aging the cathode with several tens of voltage pulses at a field of 1–2 MV/cm provides a stray emission delay ranging from hundreds of picoseconds to a nanosecond or more. In addition, the magnetic field must be configured so that the magnetic lines would not cross the vacuum gap between the diode case and the cathode holder in the region behind the emitting edge of the cathode. These efforts provide conditions for stable emission of the working beam from a graphite cathode with a sharp emitting edge.

On the low-energy high-current electron beam profile controlled using ferromagnetic insertions

We report on the results of investigation of the energy density distribution over the cross section of a low-energy (10–30 keV) high-current (up to 25 kA) electron beam transported in the plasma channel in a guiding magnetic field. Beam focusing and energy density redistribution in the beam cross section are carried out using hollow cylindrical insertions prepared from a ferromagnetic steel (magnetic-field concentrators) and installed behind a foil collector (made of nonmagnetic stainless steel of thickness 200 μm). The energy density distribution is measured by an infrared imager; for this purpose, the concentrator is moved aside by an electromagnet during the pause (about 1 s) between a beam pulse and the instant of thermogram recording. The experiments confirm the possibility of improving the beam homogeneity in the cross section by using magnetic field concentrators. The results of measurements are in satisfactory agreement with the earlier results of calculations.

NAS NM17

Abstract NAS NM 17 has high manganese (17%), with 7.5% nickel and is a soft nonmagnetic stainless steel. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming and heat treating. Filing Code: SS-1201. Producer or source: Nippon Yakin Kogyo Company Ltd.