[en] The behaviour of AISI 310 stainless steel during monoaxial tensile tests is studied in this paper. We begin by examining the mechanical characteristics over a wide range of temperatures (293-1173 K) for two different cross-head velocities (3.33 x 10^-7 ms^-1) and find them to be in good agreement with those already reported in the literature. (orig.)

[en] The goal of this study is to identify the predominant grain boundary factor (sensitization versus embrittlement) that controls the intergranular stress corrosion cracking (IGSCC) susceptibility of austenitic stainless steel Type 310S exposed to supercritical water (SCW). Pre-treatments involving thermal ageing at high temperature in combination with plastic deformation were applied to induce specific types of grain boundary structure instability such as solute segregation, secondary phase precipitation and dislocation channeling. Each of these structural instabilities was independently assessed in terms of the susceptibility to both grain boundary sensitization and embrittlement in order to construct a 2-D property assessment grid Grain boundary sensitization was assessed using the double loop electrochemical potentiokinetic (DL-EPR) technique. Grain boundary embrittlement was assessed using nano-indentation and nano-scratching techniques. The susceptibility of the various degraded material will be evaluated using slow strain rate testing (SSRT) in 25 MPa SCW at 500 °C with 8 ppm dissolved oxygen in an autoclave flow loop (200 mL/min.) facility. This paper presents and discusses the results of our attempt to link the IGSCC susceptibility to a particular grain boundary degradation signature. (author)

[en] The STS310S tube has excellent heat transfer ability and is widely used as the material for heat transfer tubes in heat exchange devices. Mixtures of gas and water flow inside the tube whereas hot flame flows outside it. In this environment, the material of the tube may undergo embrittlement, which can cause leakage. Cracks can propagate from the inside of the tube to its outside and result in brittle fracture. This study identified the cause of brittle fracture in the STS310S tube through experiments and discussion, and proposed solutions to prevent fracture

[en] Fracture toughness tests were performed on annealed austenitic stainless steel AISI 310S, immersed in liquid helium at 4 K, using 25-mm-thick compact specimens. The J_Ic results (360 to 380 kJ/m²) from single- and multiple-specimen test techniques are compared and shown to be in close agreement. Attention is called to the remarkable failure process of this steel at 4 K: crack extension occurs by ductile tearing, while the test records exhibit serrations due to repeated bursts of unstable plastic flow and arrests. The nature of this behavior is discussed, and the performance of stable austenitic AISI 310S is compared with that of related steels, including those that transform from austenite to martensite during testing at 4 K

[en] To evaluate the influence of minor and impurity elements such as C, Mn, P and S on the solidification and ductility-dip cracking susceptibilities of extra high-purity type 310 stainless steels, the transverse-Varestraint test was conducted by using several type 310 stainless steels with different amounts of C, Mn, P and S. 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 amounts of C, P and S decreased. The ductility-dip cracking susceptibility also reduced with a decrease in P and S contents. It adversely, however, increased as the C content of the steels was reduced. Mn didn't greatly affect the hot cracking susceptibility of the extra high-purity steels. The characteristic influence on solidification cracking was the ratio of P:S:C=1:1.3:0.56, while Mn negligibly ameliorated solidification cracking in the extra low S (and P) steels. The numerical analysis on the solidification brittle temperature range (BTR) revealed that the reduced solidification cracking susceptibility with decreasing the amounts of C, P and S in steel could be attributed to the reduced BTR due to the suppression of solidification segregation of minor and impurity elements in the finally solidified liquid film between dendrites. On the other hand, a molecular orbital analysis to estimate the binding strength of the grain boundary suggested that the increased ductility-dip cracking susceptibility in extra high-purity steels was caused by grain boundary embrittlement due to the refining of beneficial elements for grain boundary strengthening such as C. (author)

[en] Orientations of stress corrosion cracks have been determined in single crystals of Type 316, Type 310 and few experimental steels. The cracks are more irregular in Type 316 than in Type 310 which shows tendency to form (100) facets and (100) crack planes. The electrochemical behaviour of crystal slices did not vary systematically with orientation and, although differences were detected, it is considered that faster repassivation on (100) crystal faces is not the explanation of the observed crack plane orientation. Cross slip of dislocations was identified from slip-traces at the surface and indicates a localisation of slip to surface regions which could be associated with local stress relaxation. Such processes would increase the aspect ratio if they occurred in the bulk and increased the number of dislocations operating in a given crack length. Toward the crack tips fairly regular slip steps of about 30 nm spaced at 1 m were observed but smaller steps (10nm) and spacings (70nm) could be detected on shadowed carbon replicas at some cracks however, the crack advance between slip steps is considerable. (author)

[en] Transient creep of hydrogen-austenitic stainless steel solid solutions at 55 C was studied to determine the effects of hydrogen on plastic deformation. Thin specimens at AISI 310S stainless steel were slowly cathodically charged to uniform hydrogen contents, and no significant damage was introduced. A constant load was then applied, while the charging current density remained the same, so as to prevent outgassing of the hydrogen during the tests. It was found that at short times the creep rate of a hydrogenated specimen was lower than that of specimen without hydrogen. However, the creep rate decreased at a slower rate thereafter, so that the transient creep stage was longer, and in some cases the creep was even larger than in a hydrogen-free specimen. This is clear evidence of hydrogen-enhanced plasticity. Elasticity interactions between hydrogen atmospheres and moving dislocations were used to explain the observed phenomenon. Hydrogen enhancement and localization of plasticity have been cited as fundamental causes of hydrogen embrittlement. The prolongation of the transient creep stage has significance for propagation of stress corrosion cracks. (orig.)

[en] The sulfidation of SAE 310 stainless steel was carried out in gas mixtures of hydrogen and hydrogen sulfide over a range of sulfur potentials anticipated in advanced coal gasification processes. The kinetics, composition, and morphology of sulfide scale formation were studied at a fixed temperature of 1065 K over a range of sulfur potentials from 1.5 x 10^-4 Nm^-2 to 9 x 10² Nm^-2. At all sulfur potentials investigated, the sulfide scales were found to be multilayered. The relative thickness of the individual layers as well as the composition was found to depend on the sulfur potential. The reaction was found to obey the parabolic rate law after an initial transient period. Considerably longer transient periods were found to be due to unsteady state conditions resulting from compositional variations in the spinel layer. The sulfur pressure dependence on the parabolic rate constant was found to best fit the equation: K/sub p/ = Const. P/sub S₂//sup 1/n/, where n equals 3.7. The growth of the outer layers was found to be primarily due to the diffusion of metal ions, iron being the predominant species. The inner layer growth was due to the dissociation of the primary product at the alloy-scale interface and depended on the activity of chromium

[en] In the process of micro milling stainless steel 310S, the influence of milling parameters (cutting depth, a _p , feed per tooth f _z , cutting speed v),and down and up milling method were revealed, which provides reference for controlling burrs of stainless steel 310S, improving surface quality and optimizing cutting process. Based on the orthogonal test method, the coated carbide micro diameter cutter was used and milling experiments were carried out on stainless steel 310S.Top burr size data information was collected and analyzed. Up milling is better than down milling because the shape and size of burr are relatively small. With the increase of cutting depth, the shape of burrs appears long fibrous and tearing and wavy serrated, which means the burr getting large and worse. In order to minimize burrs, it is the good way to choose the sharp cutting tools and up milling, control the cutting depth and select feed rate. (paper)

[en] This paper studies the corrosion behaviour of non-sensitized stainless steels in oxidizing environments, where they can suffer intergranular corrosion. In this case, corrosion rate estimated by gravimetric measurement is not constant as a function of time. This paper proposes a quantitative modelling of the IGC kinetics. Two models were developed: the first one is based on the geometrical simulation of the groove penetration; the second one uses a semi-empirical approach based on the typical shape of the corrosion kinetics. Both models reproduce successfully the experimental corrosion kinetics observed for a AISI 310L stainless steel corroded in nitric acid containing oxidizing ions. (authors)