SUS304 Tubes Research Articles

Butt welding of SUS304 and Inconel718 tubes by using defocused laser beam

Joining stainless steel to superalloy is currently of extensive interest for applications in aviation and automotive industries. However, conventional welding is prone to encounter defects such as cracks and austenite grain coarsening in the fusion zone. In the present study, laser welding was applied to join SUS304 stainless steel and Inconel718 superalloy circular tubes due to their precise local heat input and accuracy. The effects of defocusing distance, welding speed, and laser power on welding characteristics were studied by changing the values of the mentioned parameters, which manifested that different process parameters exerted a tremendous impact on the cross section morphology and shape of the weld seam. In addition, finite element simulation software was used to simulate temperature field distribution. The results revealed that there would be a buffering region on the temperature field once the laser power gradually decreased, which remarkably reflected the effect of the laser power descending on eliminating weld craters. Therefore, the crater defects caused by laser beam accelerating and decelerating at the start and end of welding could be effectively eliminated through synchronously regulating laser power in the real welding process.

A quantitative method of eutectic reaction study between boron carbide and stainless steel

Core Disruptive Accident (CDA) is a critical scenario in the Generation IV sodium-cooled fast reactor development. One of the key issues in the CDA evaluation is the eutectic reaction between Boron carbide (B4C) and Stainless Steel (SS). For developing a physical model in the CDA analysis code, it is necessary to investigate the B4C-SS eutectic reaction. To assess the reaction, one quantitative and high-resolution method using Joule heating is proposed in this study. Experiments were conducted using B4C material and SUS304 tubes. With an originally proposed equation, reaction rate constant data in the 1450 K-1500 K range were obtained, which was scarce in the past. The derived reaction rate constant values are consistent with the reference values. The reaction layer microstructure observation and the associated chemical composition analysis were also conducted. The proposed method is validated by the results. It can be concluded that the new method is credible with high efficiency.

Experimental and numerical investigation on the shearing process of stainless steel thin-walled tubes in the spent fuel reprocessing

Abstract The SUS304 stainless steel thin-walled tube (SUS304 tube) is an important part of the simulated spent fuel assembly (SSFA). During the shearing process, owing to the high ductility and malleability of the SUS304 tube, the local stress concentration easily occurs on the shear tool, resulting in such damages as tool tipping and breaking. However, the investigation on the shearing of the SUS304 tube has been scarce so far. In this contribution, the modified Gurson-Tvergaard-Needleman model (GTN-J model) was adopted to investigate the fracture mechanism of the SUS304 tube under the complex stress state. It is proved that the GTN-J model performs perfectly in the simulation of the entire shearing process by comparing the results of shear experiments with simulations. Moreover, The results reveal that the local stress concentration of the shear tool is mainly caused by irregular plastic deformation of the SUS304 tube.

Conditions for Wall Thickness Reduction in Hollow Sinking of SUS304 Tubes With Drawing Speed Control in Entrance and Exit Sides of Die

Abstract In this study, the conditions for wall thickness reduction in hollow sinking were obtained by tube drawing experiments in which the drawing speed ratio was controlled under three conditions (1.09, 1.11, and 1.14). These conditions have not been found in the history of hollow sinking. The results of the experiment and the theoretical formulas indicate that the geometric condition is obtained from the figure of the ratio of inner diameter to outer diameter after drawing against that ratio before drawing. Furthermore, the ratio of the inner diameter to the outer diameter after drawing must be above the constant wall thickness line derived from the cross-sectional change. To satisfy this geometric condition, the drawing speed ratio must be larger than the threshold value, which is obtained from the ratio of the inner diameter to the outer diameter before drawing, and the reduction of the die. However, the value of the back stress approaches that of the strength of the tube when the drawing speed ratio increases. A simple dynamical model shows that parameters other than the drawing speed ratio do not significantly decrease the back stress during drawing. Therefore, the drawing speed ratio should be set such that the tube does not break.

Application of v-shaped magnet in inner surface polishing of tubes

Compared to traditional polishing processes, the magnetic grinding method allows relatively easy polishing of the inner surface of tube fittings. For more than 7 mm thickness SUS304 tubes, the magnetic abrasive grains are subject to a small magnetic force and grinding pressure, leading to the low polishing efficiency. Therefore, a new magnetic grinding and polishing method is proposed, in which the grooved V-shaped magnet is conductive to spontaneous mixing and stirring with magnetic abrasive grains, allowing them continually being replaced for inner surfaces polishing on the tube. This can increase the grinding pressure of abrasive grains to the inner surface and contribute to high-quality surface polishing. Theoretically, it was proved that the grooved V-shaped magnet-assisted polishing tool improves the uniformity of material cutting force in the polishing process. Finally, this method was validated by the experiment with the 7 mm thickness SUS304 tube.

A new approach in producing metal bellows by local arc heating: a parametric study

Recently, dieless forming processes have been introduced to prevent the high costs of dies and tools. Local heating and axial compression process is an innovative method for producing metal bellows. In this research, producing metal bellows using simultaneous local electric arc heating and axial compression has been explained and investigated. SUS304 tubes with an outer diameter of 19 mm and a thickness of 1 mm have been employed to implement the tests. Various parameters could affect the process. Among these parameters, effects of applied displacement and device current, influencing convolution shape, thickness, and required forming force, are studied experimentally. It is found that the height, radius, and angle of the convolution and also the forming force could be controlled by alteration of these parameters. Furthermore, the result of buckling test showed that energy absorption capacity of the manufactured metal bellow has been increased in comparison to a typical tube. This method could be a suitable alternative for induction local heating and can reduce the high equipment costs.

Transient heat transfer due to exponentially increasing heat inputs for turbulent flow of FC-72 in small diameter tubes

The transient heat transfer process due to exponentially increasing heat inputs for turbulent flow of FC-72 was schematically investigated for different combinations of parameters such as flow velocity, inlet liquid temperature and period of exponentially increasing heat inputs. The ranges of Reynolds number, Red, and Prandtl number, Pr, were 23,400–81,800 and 8.4–10.8, respectively. The test heaters used in this study were circular SUS304 tubes with small inner diameters of 1, 1.8 and 2.8mm, wall thickness of 0.5mm, and heated lengths around 30, 40 and 50mm. The effects of flow velocity, exponential period and tube inner diameter on transient turbulent heat transfer process were discussed in detail. It was clarified that the transient turbulent heat transfer due to exponentially increasing heat inputs could be analyzed by introducing a dimensionless time, Fourier number, Fo. An empirical correlation for transient turbulent heat transfer caused by exponentially increasing heat inputs on small diameter tubes was developed based on the effects of Fo, flow velocity and tube inner diameter. The empirical correlation presents the experimental data within ±25%.

Macroporous zirconia particles prepared by subcritical water in batch and flow processes

Porous zirconia particles were synthesized through a low-temperature hydrothermal synthesis process. Under hydrothermal conditions, water can control the direction of crystal growth, morphology, particle size, and size distribution because thermodynamics and transport properties can be controlled by pressure and temperature. In a batch process, the hydrothermal synthesis was conducted at 200–300 °C and 30 MPa with an SUS-304 tube as the reactor. At the same reaction pressure, experiments were also performed for a flow process with temperatures of 180–200 °C. The synthesized products were calcined and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The results showed that the macroporous zirconia particles that were formed had pore diameters around 419 nm. The XRD pattern indicated that the products were composed of zirconium oxide particles with monoclinic, tetragonal, and cubic structures.

구리튜브를 피복재로 이용한 분말시스압연법에 의해 제조된 CNT/Al 복합재료의 미세조직 및 기계적 특성

A powder-in-sheath rolling (PSR) process utilizing a copper alloy tube was applied to a fabrication of a multi-walled carbon nanotube (CNT) reinforced aluminum matrix composite. A copper tube with an outer diameter of 30 mm and a wall thickness of 2 mm was used as a sheath material. A mixture of pure aluminum powders and CNTs with the volume contents of 1, 3, 5 vol% was filled in the tube by tap filling and then processed to 93.3% height reduction by a rolling mill. The relative density of the CNT/Al composite fabricated by the PSR decreased slightly with increasing of CNTs content, but showed high value more than 98%. The average hardness of the 5%CNT/Al composite increased more than 3 times, compared to that of unreinforced pure Al powder compaction. The hardness of the CNT/Al composites was some higher than that of the composites fabricated by PSR using SUS304 tube. Therefore, it is concluded that the type of tube affects largely on the mechanical properties of the CNT/Al composites in the PSR process.

Process Parameter with High Expansion Rate of SUS304 Tube Hydroforming

Stainless steel has been applied more and more extensively because it has good corrosion resistance and its surface is glossy, like a mirror after polishing. Thus, it is used in high-price pieces or quality goods. In this paper, the SUS 304 has been used to form a product with high expansion rate, via tube hydroforming technology, applying different feeding of two ends with different inner pressure to complete the procedure. The effects of different loading paths on product quality are discussed in this paper. Finally, by reasonable feeding with pressure parameters and a preforming process, a product with high expansion rate has been realized. The diameter-to-thickness ratio is 110, with an expansion rate of about 45%. The deviation of results from the experiment and simulation are also discussed in this paper. The results of this study could provide significant information to benefit industry.

922 金属マイクロチューブのダイレス引抜き過程における変形挙動に及ぼす表面性状の影響

Microtube is commonly used and required. Dieless drawing is fabrication process of microtube. However, in the dieless drawing process, oxidation occurs on tube surface because of local heating and it reduces reduction in area. In this study, methods of fabrication process of non-oxide tubes and the effect of surface quality on deformation behavior in dieless drawing process for metal microtubes was investigated. Materials used are stainless SUS304 tubes and copper alloy C1220 tubes. SUS304 tubes with outer diameter of 500μm and thickness of 130μm and 100μm. C1220 tubes with outer diameter of 500μm and thickness of 130μm. As a result, argon gas atmosphere reduced oxide film on the tube surface in dieless drawing process. In case of low temperature, oxide film decreases the limiting reduction in area. On the contrary, in case of high temperature, oxide film enhances the limiting reduction in area, because surface roughness with oxide film is lower than that of non-oxide film under condition of argon gas atmosphere.

Influence of a Flow Obstacle on Boiling Two-Phase Flow

In the view of the safety operation and the designing of boiling two-phase flow equipments, boiling two-phase flow characteristics, especially the critical heat flux is very important. In addition, the flow obstacle in a boiling channel, such as the spacer of boiling water reactor, influences the boiling heat transfer and flow characteristics. In this study, the experimental investigation was conducted by using a SUS304 tube (I.D. = 8 mm, LT =810, 840 and 900 mm) in which a rod-type flow obstacle (O.D. = 3.6 mm L = 20 mm) was equipped. Two kinds of detecting points of CHF, i.e. at the upstream of the flow obstacle and at the exit of the test section were observed. The difference of the detecting location of the CHF has been explained well by using the film flow model. On the basis of these results the influence length of the turbulent effect by the flow obstacle and the magnitude of the entrainment caused by the boiling were estimated.

B208 流動障害物設置による沸騰二相流への影響(OS8 熱流動),動力エネルギーシステム部門20周年,次の20年への新展開)

Flow obstacle in a boiling channel, such as a spacer of water reactor, influences the boiling heat transfer and flow characteristics. In this study, the experimental investigation was conducted by using a SUS304 tube which had 8 mm in tube diameter and 810, 840, 900 mm in heated length. The test section equipped with the rod-type flow obstacle which had 3.6 mm in cylinder diameter and 20mm in length. On the basis of the detecting point of CHF, CHF in this investigation was classified into two categories. The difference of the location of the CHF has been explained by using the film flow model with influence length of the turbulent effect by flow obstacle.

Influence of heat input waveform on transient critical heat flux of subcooled water flow boiling in a short vertical tube

The transient critical heat fluxes (CHFs) of the subcooled water flow boiling for ramp-wise heat input [ Q = αt, α = 6.21 × 10 8 to 1.63 × 10 12 W/m 3 s, ( q ≅ 1.08 × 10 7 to 6.00 × 10 7 W/m 2)] and stepwise one [ Q = Q s , Q s = 0 W/m 3 at t = 0 s and Q s = 2.95 × 10 10 to 7.67 × 10 10 W/m 3 at t > 0 s, ( q = 0 W/m 2 at t = 0 s and q ≅ 1.61 × 10 7 to 3.87 × 10 7 W/m 2 at t > 0 s)] with the flow velocities ( u = 4.0–13.3 m/s), the inlet subcoolings (Δ T sub, in = 86.8–153.3 K) and the inlet pressures ( P in = 742.2–1293.4 kPa) are systematically measured by an experimental water loop comprised of a pressurizer. The SUS304 tubes of inner diameters ( d = 3, 6 and 9 mm), heated lengths ( L = 33.15, 59.5 and 49.3 mm), L/ d (=11.05, 9.92 and 5.48), and wall thickness ( δ = 0.5, 0.5 and 0.3 mm) respectively with the rough finished inner surface (surface roughness, Ra = 3.18 μm) are used in this work. The experimental errors in the subcooling measure and the pressure one are ±1 K and ±1 kPa, while in the heat flux it is ±2%. The transient CHF data for the ramp-wise heat input and the stepwise one are compared with those for the exponentially increasing heat input ( Q = Q 0 exp( t/ τ), τ = 16.82 ms to 15.52 s) previously obtained and the dominant variables on transient CHF for heat input waveform difference are confirmed. The transient CHF data are compared with the values calculated by the steady state CHF correlations against inlet and outlet subcoolings, and the applicability of steady state CHF correlations is confirmed extending its possible validity for the reduced time, ω p , down to 800 ms. The transient CHF data are compared with the values calculated by the transient CHF correlations against inlet and outlet subcoolings, and the influence of heat input waveform on transient CHF is clarified based on the experimental data for the ramp-wise heat input, the stepwise one and the exponentially increasing one. The dominant mechanisms of the subcooled flow boiling critical heat flux for the ramp-wise heat input, the stepwise one and the exponentially increasing one are discussed.

Transient Critical Heat Fluxes of Subcooled Water Flow Boiling in a Short Vertical Tube Caused by Exponentially Increasing Heat Inputs

The transient critical heat fluxes (CHFs) of the subcooled water flow boiling for the flow velocities (u=4.0–13.3m∕s), the inlet subcoolings (ΔTsub,in=68.08–161.12K), the inlet pressures (Pin=718.31–1314.62kPa), the dissolved oxygen concentrations (O2=2.94ppm to the saturated one), and the exponentially increasing heat inputs (Q0exp(t∕τ), τ=16.82msto15.52s) are systematically measured with an experimental water loop comprised of a pressurizer. The SUS304 tubes of the inner diameters (d=3mm, 6mm, 9mm, and 12mm), heated lengths (L=33.15–132.9mm), L∕d=5.48–11.08, and wall thickness (δ=0.3mm and 0.5mm) with the rough finished inner surface (surface roughness, Ra=3.18μm) are used in this work. The transient CHF data (qcr,sub=6.91–60MW∕m2) are compared with the values calculated by the steady state CHF correlations against inlet and outlet subcoolings. The transient CHF correlations against inlet and outlet subcoolings are derived based on the experimental data. The dominant mechanisms of the subcooled flow boiling CHF for a high heating rate are discussed.

Influence of Heating Rate on Subcooled Flow Boiling Critical Heat Flux in a Short Vertical Tube

The subcooled flow boiling critical heat flux (CHF) for the flow velocities (u = 4.0 to 13.3 m/s), the inlet subcoolings (ΔT sub, in = 130 to 161 K), the inlet pressure (Pin = 812 to 1 315 kPa), the dissolved oxygen concentration (O 2 = 5.88 and 7.34 ppm) and the increasing heat input (Qoexp(t/r), r = 38.1 ms to 8.3 s) are systematically measured by the experimental water loop installed the pressurizer. The SUS304 tube of test tube inner diameter (d = 6 mm), heated length (L = 60 mm), L/d= 10 and wall thickness (δ=0.5 mm) with the rough finished inner surface (Surface roughness, Ra = 3.18 μm) is used in this work. The CHF data for high heating rate were compared with the quasi steady state ones previously obtained and the values calculated by the steady state CHF correlations against outlet and inlet subcoolings. Transient CHF correlation against inlet subcooling has been given based on the experimental data for wide exponentially increasing heat input (Q 0 exp(t/τ), τ = 38.1 ms to 8.3 s). The influence of heating rate on CHF was investigated into details and the dominant mechanism of subcooled flow boiling critical heat flux for high heating rate was discussed.

Critical Heat Flux in Non-uniformly Heated Tube under Low-Pressure and Low-Mass-Flux Condition

In an actual boiling channel, e.g. boililer water-tubes, the circumferential heat flux is not uniform. Thus, critical heat flux (CHF) of non-uniformly heated tube becomes an important design factor of conventional boilers, especially for the compact water-tube boiler with tube-nested combustor. The small compact boiler is operated at low-pressure and low-mass flux condition compared with the large scale boiler, thus the redistribution of liquid film will strongly affect on the characteristics of CHF. In this investigation, non-uniformly heat flux distribution along the circumferential direction was generated by using the Joule heating of SUS304 tubes which had the wall thickness distribution. The heated length of test-section was 900mm, inner diameter was 20mm and outer diameter was 24mm. The center of the inner tube surface was shifted by ε=0, 0.5, 1.0, 1.5mm from the center of the outer tube surface. The heat flux ratio between maximum and minimum heat fluxes of these tubes correspond to 1.0, 1.7, 3.0 and 7.0, respectively. Experimental conditions were as follows ; system pressures were 0.3 and 0.4 MPa, mass flux range were 10-100kg/m2s, inlet temperatures were 30 and 80 deg. C. The experimental results showed an increase in the critical heat flux by the existence of the redistribution of the flow. These characteristics have been well explained by using the similar concept of Butterworth's spreading model.

Critical heat flux in non-uniformly heated tube under low-pressure and low-mass-flux condition

In an actual boiling channel, e.g., a boiler water-tube, the circumferential heat flux is not uniform. Thus, the critical heat flux (CHF) of a non-uniformly heated tube becomes an important design factor for conventional boilers, especially for a compact water-tube boiler with a tube-nested combustor. A small compact boiler is operated under low-pressure and low-mass-flux conditions compared with a large-scale boiler, thus the redistribution of liquid film strongly affects the characteristics of CHF. In this investigation, non-uniform heat flux distribution along the circumferential direction was generated by using the Joule heating of SUS304 tubes with the wall thickness distribution. The heated length of test-section was 900 mm with an inner diameter of 20 mm and an outer diameter of 24 mm. The center of the inner tube surface was shifted by e=0, 0.5, 1.0, 1.5 mm from the center of the outer tube surface. The heat flux ratio between maximum and minimum heat flux of these tubes corresponded to 1.0, 1.7, 3.0, and 7.0, respectively. The experimental conditions were as follows: system pressure at 0.3 and 0.4 MPa, mass flux of 10–100kg/(m2s), inlet temperatures at 30° and 80°. The experimental results showed an increase in the critical heat flux substantiated by the existence of the redistribution of the flow. These characteristics are explained by using a concept similar to that of Butterworth's spreading model. © 2005 Wiley Periodicals, Inc. Heat Trans Asian Res, 35(1): 47–60, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20095

Critical Heat Fluxes of Subcooled Water Flow Boiling against Inlet Subcooling in Short Vertical Tube

The critical heat fluxes (CHFs) of subcooled water flow boiling for the test tube inner diameters (d=3 and 6mm) and the heated lengths (L=67, 120 and 150mm) are systematically measured for the flow velocities (u=4.0 to 13.3m/s), the inlet subcoolings (ΔTsub, in=48 to 148K), the outlet subcoolings (ΔTsub, out=10.5 to 95.1K), the inlet pressure (Pin=753 to 995kPa) and the outlet pressure (Pout=720 to 887kPa). The SUS304 tubes of L=67, 120 and 150mm for d=3mm and L=150mm for d=6mm are used. The values of L/d are 22, 40 and 50 for d=3mm, and 25 for d=6mm, respectively. The CHFs, qcr, sub, for a fixed ΔTsub, out become gradually lower with an increase in the L/d in the whole experimental range. The CHF correlation against outlet subcooling, which has been previously derived for L/d lower than 16, was modified to new one containing the L/d effect based on these experimental data. Furthermore, the relation between qcr, sub and L/d for a fixed ΔTsub, in was checked. The values of qcr, sub for a fixed ΔTsub, in became exponentially lower with the increase in L/d. CHF correlation against inlet subcooling has been given based on the experimental data for L/d ranging from 4.08 to 50. The correlations against outlet and inlet subcoolings can describe not only the CHFs obtained in this work for the inner diameter of 3 and 6mm at the outlet pressure of around 800kPa but also the authors' published CHFs data (1611 points) for the wide ranges of Pin=159kPa to 1MPa, d=3 to 12mm, L=33 to 150mm and u=4.0 to 13.3m/s within 15% difference for 30K≤ΔTsub, out≤140K and 40K≤ΔTsub, in≤151K.

An analysis of the nosing process of metal tubes

In this paper, the finite element method is used to investigate the cold nosing process of partially laterally constrained metal tubes with a conical die from a tube billet. A series of simulations on the tube nosing using the FEM program ANSYS/LS-DYNA was carried out. The influences of the process parameters such as tube length, tube thickness, die fillet radius, die angle, friction factor, strength coefficient and strain hardening exponent of the billet material on the critical nosing ratio of the tube are analysed. Experiments were carried out with stainless steel SUS304 tube billets at room temperature, and the results of experiments were compared with the FEM calculations.