Type 310S Research Articles

In situ observation of solidification crack propagation for type 310S and 316L stainless steels during TIG welding using synchrotron X-ray imaging

In situ observation of solidification cracking at the weld bead during tungsten inert gas (TIG) welding for type 310S and 316L austenitic stainless steels without the application of an external force was carried out using synchrotron X-ray radiography. The temperature distribution at the weld bead was simultaneously measured using a high-speed camera to directly determine the temperature, in which the propagation of solidification cracking occurred. The solidification cracking was clearly identified and it continuously propagated in the welding direction. The interface of the solidification cracking showed an irregular and zigzag morphology. It was found that the tip velocity of the solidification cracking periodically changed by translating between the high solid fraction (~ 90%) and the relatively lower solid fraction (~ 70%) regions at the centerline of the weld bead for both the type 310S and 316L stainless steels. The solidification cracking propagated at the lower temperature than the solidus temperature due to the segregation of low melting-point components. The tensile strain and strain rate were highly localized in the propagated area every 0.1 s which was the almost same as the time period, in which the tip velocity of the solidification cracking remarkably increased. The periodicity of the solidification cracking velocity at the weld bead can be explained by the dendrite morphology at each solid fraction and strain rate.

Microstructural evolution and solidification cracking susceptibility of grain boundary engineered fully austenitic stainless steel

Solidification cracking has been a serious problem in austenitic stainless steels. Since solidification cracking often occurs at the solidification grain boundary, the grain boundary character distribution (GBCD) in the weld metal may affect the solidification cracking susceptibility. On the other hand, the columnar grains of the weld metal are formed by the epitaxial growth from the grains in the base metal. Therefore, it is expected that microstructure and cracking susceptibility of the weld metal can be reduced by controlling the microstructure of the base metal. In this study, the effect of microstructure of the base metal on the microstructure and solidification cracking susceptibility of the weld metal was examined. The GBCDs of the base metal of the type 310S stainless steel were changed by the thermomechanical process. The solidification cracking susceptibility was evaluated by the Trans-Varestraint test. The thermomechanically processed specimen had larger ratio of coincidence site lattice (CSL) boundaries compared with those of the as-received specimen. Moreover, the specimen was found less susceptible to solidification cracking than was the as-received material. The GBCD analysis indicated that the complex shape and distribution of the grain boundaries in the thermomechanically processed specimen affect the initiation and propagation of solidification cracks.

Hot cracking susceptibility and solidification segregation analysis by computer simulation in duplex stainless steels

ABSTRACT Solidification cracking susceptibility in arc & laser welding of DSSs (duplex stainless steels) was quantitatively evaluated and the numerical simulation of solidification cracking susceptibility has clarified the affecting factors. The BTRs (brittle temperature ranges) of standard, lean and super DSSs in GTAW were 58 K, 60 K and 76 K, respectively. The solidification cracking susceptibilities of DSSs were lower than those of austenitic stainless steels with A-mode solidification modes. The BTRs of standard, lean and super DSSs in LBW were 40 K, 45 K and 56 K in LBW, respectively. The BTRs in LBW were reduced by 15–20 K compared to those in GTAW. These results suggested that DSSs had a significantly low risk of solidification cracking in LBW as well as GTAW. In order to clarify the affecting factors of solidification cracking, numerical simulation of solidification cracking susceptibility was carried out. The segregated concentrations of P, S and C in LBW were slightly lower than those in GTAW, suggesting that the solidification cracking susceptibility in LBW was reduced to GTAW attributed to the inhibition of solidification segregation because of the rapid solidification in LBW. In addition, we discussed that there is a difference in the hot cracking susceptibility compared with the austenitic stainless steel having the A mode. To explain this phenomenon, the segregation amounts of S and P by arc, laser and solidification modes were investigated. The segregation of Standard DSS was lower than that of Type310S when using the same amount of P and S. This clearly indicates that F mode solidification was less segregated than A mode solidification. This is because the equilibrium partition coefficient and the diffusion coefficient of the standard DSS are larger than that of Type 310S.

Stress corrosion cracking susceptibility of thermally-aged Type 310S stainless steels in supercritical water

The effect of thermal ageing on the stress corrosion cracking (SCC) susceptibility of Type 310S stainless steel in supercritical water (coolant for a supercritical water cooled reactor design concept) was evaluated. SCC was evaluated using the slow strain rate testing technique, straining samples to 10% in a flowing autoclave test facility using 25 MPa SCW at 500 °C with 20 ppm dissolved oxygen. The localized deformation model for SCC initiation and a void-assisted film-cleavage model for SCC propagation can be used to explain the SCC susceptibility exhibited by the thermally-aged Type 310S stainless steel in supercritical water.

Corrosion behaviour of austenitic stainless steels in carbonate melt at 923 K under controlled CO2-O2 environment

Corrosion behaviour of austenitic stainless steels (SS) was studied in carbonate melt for high temperature solar thermal systems. Corrosion resistance of type 310S, 316L and 304 SS is different from each other and increases with increasing Cr and Ni content in the substrate. 310S SS is significantly ennobled in the melt as compared to 316L SS or 304 SS. Corrosion process of SS in the carbonate melt is a mixed control of both anodic and cathodic reactions. Metallic fragments from the substrate are incorporated in the corrosion layer and the degree of incorporation is different for each SS.

Stability of type 310S stainless steel bipolar plates tested at various current densities in proton exchange membrane fuel cells

Type 310S stainless steel bipolar plate is investigated by means of single cell operated at several current densities for 500h. During the cell operations, the voltage decay is drastic at a lower current density (139mV at 0Acm−2), while the fluctuation is mitigated at a higher current density (21mV at 0.5Acm−2). The operation results are highly related to the surface conditions of bipolar plates, in particular, the cathode part. At the lower current density, the thickened layer mainly composed of iron oxide layers appears. Meanwhile, the outermost surface is enriched with thin chromium oxide layers when the higher current is applied. It is likely that the thick passive layer on the type 310S stainless steel increases the interfacial contact resistance between the gas diffusion layer and the bipolar plates of the cathode, thereby resulting in progressive voltage decay during the operation. Interestingly, general corrosion is not involved throughout the cell operation, confirming the superiority of type 310S stainless steel under the cell operation environment.

Comparative Corrosion Behavior of Austenitic Stainless Steels in Carbonate Melt at 650 °C Under Controlled CO2-O2 Environment

Concentrated solar power (CSP) has recently attracted much attention as clean energy mainly for base load applications. High temperature CSP technology has high efficiency and it can attract wide commercial applications. Corrosion of metallic materials is a key problem for high temperature CSP systems. Careful selection of molten medium and metallic material can slow down the corrosion processes and hence extend the overall life span of CSP plants. High temperature oils and nitrate-based salts are commonly used for commercial CSP plants. These materials are not stable at temperature higher than 600 °C. However, alkali metal carbonates are stable beyond 800 °C and have working temperature of ~ 400-800 °C. These carbonates are less expensive and more environment friendly than the state-of-art high temperature oils [1]. Employing high corrosion resistance of cheaper alloys, like stainless steels, could significantly promote the popularity of CSP plants. In this study, corrosion behavior of austenitic stainless steels (SS) is observed in ternary alkali carbonate melt at 650 °C under defined CO2-O2 gas environment. Weight loss, electrochemical characterization and morphological and microstructural examination were carried out to understand the corrosion behavior of Type 304 SS, Type 316L SS and Type 310S SS in 43Li2CO3-31.5Na2CO3-25K2CO3 (mol%) melt at 650 °C under flowing 0.98 atm CO2-0.02 atm O2 mixed gas. Weight loss observed due to 24 hours corrosion is 7.7 mg cm-2 for Type 304 SS, 6.5 mg cm-2 for Type 316L SS and 1 mg cm-2 for Type 310S SS. Potentiodynamic polarization showed that corrosion of SS is a cathodic-controlled process. Corrosion potential of Type 310S SS is nobler than that of Type 316L and Type 304 SS. Reduced weight loss of Type 310S SS due to corrosion should be due to high potential of anode reaction. Cathodic limiting current is not significantly different for all the SS; however, it is slightly higher for Type 304 SS than that of Type 316L and should be responsible for slightly higher weight loss of Type 304 SS. Anodic polarization behavior well agrees with the weight loss observed for all the examined SS. SEM and EDS analysis showed that a very thin Cr-rich uniform corrosion layer is formed on Type 310S; however, thicker corrosion layer formed on Type 304 is composed of a heterogeneous mixture of Cr- and Fe-rich phases. Corrosion layer formed on Type 316L is Cr-rich but locally contains Fe-rich phases. Corrosion resistance of SS in carbonate melt in decreasing order is as: Type 310S>Type 316L>Type 304. This work was supported by Council for Science, Technology and Innovation (CSTI), Cross-ministerial Strategic Innovation Promotion Program (SIP), “energy carrier” (Funding agency: JST). Reference K. Vignarooban, X. Xu, A. Arvay, K. Hsu, A. M. Kannan, Applied Energy, 146 (2015) 383-396

Effect of Hydrogen on Tensile Properties of Ultrafine-Grained Type 310S Austenitic Stainless Steel Processed by High-Pressure Torsion

This study addresses a hydrogen effect on the tensile properties of a type 310S austenitic stainless steel with ultrafine-grained structures produced by high-pressure torsion (HPT) and subsequent annealing. The mean grain size was reduced to ~85 nm by the HPT processing. The grain size was increased by the post-HPT annealing, but the grain size of ~265 nm was retained after annealing at 1023 K (750 °C). The tensile strength of ~1.2 GPa, which is approximately twice as much as that of the solution-treated specimen, was attained in the 1023 K (750 °C) post-HPT-annealed specimen. The elongation to failure was restored up to ~15 pct by the post-HPT annealing, although it was still insufficient in comparison with the ~55 pct elongation of the solution-treated specimen. There was no change in the tensile strength of the HPT-processed specimens and the post-HPT-annealed specimens by hydrogen charging with the hydrogen content in the range of ~20 to 40 mass ppm. The HPT-processed and the 773 K (500 °C) post-HPT-annealed specimens exhibited a ductility loss through the fully shear type fracture. The hydrogen charge into higher temperature post-HPT-annealed specimens with σ-FeCr precipitates led to a mild hydrogen embrittlement.

Hot cracking behaviour and susceptibility of extra high purity type 310 stainless steels

Recent progress in the refining technology has enabled the production of highly pure commercial stainless steels. The hot cracking behaviour of these stainless steels was investigated with respect to type 310 stainless steel. For comparison, four types of 310 stainless steels with various amounts of minor and impurity elements such as C, P and S were used. The purity of type 310 stainless steels used was enhanced in the order of type 310<type 310S<type 310ULC<type 310EHP steels. The hot cracking susceptibility was evaluated by the transverse Varestraint test. Two types of hot cracks occurred in these steels by Varestraint test; solidification and ductility-dip cracks. The solidification cracking susceptibility was significantly reduced as the amount of C, P and S decreased, and that in type 310EHP steel reached a level so low that solidification cracking did not occur in practical welding. On the other hand, the ductility-dip cracking susceptibility adversely increased as the purity of the steels was enhanced. However, the ductility-dip cracking susceptibility of type 310EHP steel was sufficiently low as not to yield ductility-dip cracking in practical multipass welding. The experimental and numerical analyses on the solidification brittle temperature range have revealed that the reduced solidification cracking susceptibility upon decreasing the amount of C, P and S in stainless steel can be attributed to the reduced BTR due to the suppression of minor and impurity elements, such as C, P and S, in the finally solidified liquid film between the dendrite.

Nanosized TiN–SBR hybrid coating of stainless steel as bipolar plates for polymer electrolyte membrane fuel cells

In attempt to improve interfacial electrical conductivity of stainless steel for bipolar plates of polymer electrolyte membrane fuel cells, TiN nanoparticles were electrophoretically deposited on the surface of stainless steel with elastic styrene butadiene rubber (SBR) particles. From transmission electron microscopic observation, it was found that the TiN nanoparticles ( ca. 50 nm) surrounded the spherical SBR particles ( ca. 300–600 nm), forming agglomerates. They were well adhered on the surface of the type 310S stainless steel. With help of elasticity of SBR, the agglomerates were well fitted into the interfacial gap between gas diffusion layer (GDL) and stainless steel bipolar plate, and the interfacial contact resistance (ICR), simultaneously, was successfully reduced. A single cell using the TiN nanoparticles-coated bipolar plates, consequently, showed comparable cell performance with the graphite employing cell at a current density of 0.5 A cm −2 (12.5 A). Inexpensive TiN nanoparticle-coated type 310S stainless steel bipolar plates would become a possible alternate for the expensive graphite bipolar plates as use in fuel cell applications.

Nanoparticle TiN-coated type 310S stainless steel as bipolar plates for polymer electrolyte membrane fuel cell

Type 310S stainless steel was coated by TiN nanoparticles with styrene–butadiene rubber (SBR) through electrophoretic deposition. The TiN-coated and uncoated type 310S stainless steels were investigated through polarization tests in the simulated polymer electrolyte membrane fuel cell (PEFC) environments (0.05 M SO 4 2 - + 2 ppm F − solution at 353 K), interfacial contact resistance measurements between steels and carbon paper gas diffusion layer, and single cell operation up to 300 h. The surface coating with conductive TiN nanoparticles resulted in good fuel cell performance in both simulated PEFC environment and single cell operation with the help of improved interfacial conductivity.

Corrosion behavior of austenitic stainless steels as a function of pH for use as bipolar plates in polymer electrolyte membrane fuel cells

Stainless steels (types 304 and 310S) were employed as bipolar plates for polymer electrolyte membrane fuel cells. For the cell operation, the decayed cell voltage was approximately 22 mV for the type 310S stainless steel after 1000 h operation, while that for type 304 stainless steel was about 46 mV. Corrosion products appeared on the cathode side bipolar plate for the type 304 stainless steel, while trace of corrosion was barely detected for type 310S stainless steel. In order to follow the pH on the bipolar plates during fuel cell operation, polarization tests were carried out for the type 310S stainless steel in synthetic solutions (0.05 M SO 4 2− (pH 1.2–5.5) + 2 ppm F −) as a function of pH (1.2–5.5) at 353 K. We also examined the contact resistance between the stainless steel and carbon diffusion layer before and after polarization. X-ray photoelectron spectroscopic (XPS) analyses were carried out for comparison of the surface states of the steels after the polarization tests and cell operation. In the synthetic solutions with lower pHs (≤3.3), the films were thinner and were mainly composed by enriched with chromium oxide. Whereas, they mainly consisted of relatively thick iron oxide when the solution pH was higher (≥4.3). XPS analyses for the bipolar plate of type 310S stainless steel on cathode side after cell operation demonstrated pH gradient on the plate, that is, the thicker iron-rich surfaces presented relatively higher pH from the gas inlet to center area, and the thinner chromium-rich surface appeared with lower pH around the gas outlet.

Testing procedure to obtain reliable potentiodynamic polarization curves on type 310S stainless steel in alkali carbonate melts

AbstractPotentiodynamic polarization measurements have been employed to evaluate the anodic behavior of a type 310S stainless steel in the eutectic Li/K molten carbonate. In general, the electrochemical tests yield useful information to predict the stability of the oxide films formed on the surface at the initial period of corrosion, although some precaution is required in the testing procedure as the reproducibility of results is seen to be adversely affected by the passage of large currents. Especially when the steel is in a passive state, erratic results are easily observed if the corrosion layer is being damaged by uncontrolled large currents. This is because the acid‐base properties of the melt are susceptible to deep changes by applied currents in the milli‐ampere range resulting in hysteresis phenomena in the polarization plot. Hysteresis is caused, on one hand, by acidic dissolution of the passive layer at high anodic currents and, on the other hand, by increased melt basicity due to oxide ion build‐up at high cathodic currents. An optimized testing procedure is therefore suggested that minimizes these effects by imposing a 2 mA/cm2 threshold current during polarization measurements. Moreover, the conditions for the applicability of the linear polarization technique to estimate kinetic parameters have been discussed in relationship with the corrosion mechanisms analysed by impedance spectra. It is concluded that the presence of diffusional impedance terms and formation of surface resistive films in molten carbonates may result in not reliable polarization resistance values obtained with the linear polarization.

Long-term corrosion resistance of Al–Ni-plated material and Al-plated material in molten carbonate environment

Al–Ni-plated material, which was produced by Ni and Al electroplating on a Type 310S stainless steel substrate followed by heat-treating at 1023 K, has been developed for the wet-seal material of MCFC. In order to compare the corrosion resistance of Al–Ni-plated material with that of Al-plated material, which simulated the Al-sprayed material presently used as wet-seal material, an immersion test was carried out in molten carbonate in 70% air–30% CO 2 gas at 923 K for 14,500 h. Both Al–Ni-plated material and Al-plated material showed good corrosion resistance during this test period. From the analyses of the surface, in cross-section, of these materials after the test, however, it was confirmed that a large amount of Al in Al–Ni-plated material was retained as an Al–Ni intermetallic compound under the LiAlO 2 layer, while the Al in Al-plated material tended to diffuse from the surface into the substrate during the test. It is suggested that the lifetime of the Al–Ni-plated material is longer than that of the Al-plated material, since Al–Ni intermetallic compounds in the Al–Ni-plated material provide a supply of Al to the LiAlO 2 layer, the stability of which leads to prolonged corrosion resistance of the wet-seal material to molten the carbonate. Therefore, it is expected that the Al–Ni-plated material maintains a higher corrosion resistance, compared with the present material used for the wet-seal area of MCFC.

Effect of strain-induced martensite on hydrogen environment embrittlement of sensitized austenitic stainless steels at low temperatures

Hydrogen environment embrittlement (HEE) of the austenitic stainless steels of types 304, 316 and 310S with the solution-annealed, sensitized and desensitized heat treatments was investigated in hydrogen and helium of 1 MPa in the temperature range from 295 to 80 K. The effect of the strain-induced martensite, distinguished from that of the carbides, both existing along the grain boundaries in the sensitized materials, on HEE was examined. Metastable austenitic stainless steels of types 304 and 316 showed considerable HEE, but stable austenitic stainless steel of type 310S was not affected by the hydrogen environment. HEE of types 304 and 316 stainless steels depended on the testing temperature, and the maximum HEE occurred at around 220 K independent of the type of heat treatment. The susceptibility of the materials to HEE was enhanced by the sensitization, that caused intergranular fracture, and was recovered upon a transition from the intergranular fracture to the transgranular fracture due to desensitization. The strain-induced martensite was observed together with the carbides, both along the grain boundaries of the sensitized materials. As a result of desensitization, the formation of martensite along the grain boundaries was inhibited. It was evident that HEE of the sensitized materials was not due to the carbides, but to the strain-induced α′ martensite along the grain boundaries.

A comparison of two aluminizing methods for corrosion protection in the wet seal of molten carbonate fuel cells

The corrosion behavior of aluminized Type 310S stainless steel (SS) in the wet seal of molten carbonate fuel cells was investigated. Coupons of Type 310S SS were aluminized by two different aluminizing methods: thermal spray and slurry-coating. In both types of samples Fe and Cr diffused readily into the Al layer at 650 °C. At first this interdiffusion is limited to the interfacial area. With time, Fe and Cr aluminides precipitate in the Al layer. The slurry-coated layer contains a higher concentration of FeAl and Fe3Al than does the thermal spray layer. Consequently, the slurry-coated layer also displays a greater degree of corrosion than the thermal spray layer.

EASTERN STAINLESS TYPE 310S

Abstract EASTERN STAINLESS TYPE 310S has high resistance to corrosion and oxidation at high temperatures. It also has high strength at elevated temperatures. Thus it is especially suitable for service at high temperatures. It is very ductile and can be welded readily. Among the many applications for Type 310S, a few typical uses include annealing boxes, chemical plant equipment, fire box sheets, furnace linings, heat exchangers, oil-refining equipment, kiln linings and tube hangers. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as creep. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SS-450. Producer or source: Eastern Stainless Steel Company.

Technical Note: The Use of Load Pulsing in the Interpretation of Transgranular Stress-Corrosion Fracture Surfaces in a Type 310S Stainless Steel

Technical Note: The Use of Load Pulsing in the Interpretation of Transgranular Stress-Corrosion Fracture Surfaces in a Type 310S Stainless Steel

REZISTAL 310 and 310S

Abstract REZISTAL 310 is an austenitic chromium-nickel stainless steel with high heat resisting properties. It is particularly suited to intermittent heating and cooling. It is equivalent to AISI Type 310 stainless steel. Type 310S has lower carbon content, namely, 0.08 maximum. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness and creep. It also includes information on high temperature performance and corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SS-33. Producer or source: Crucible Steel Company of America.