[en] A previous study of the impact fretting wear characteristics of PE16⁺ impacting 20/25 Nb SS (carried out on the BNL twin vibrator rig) identified a pitting-transfer form of wear at 480⁰C. This behaviour was thought to be dependent upon the temperature difference ΔT(ΔT = T_20/25-T_PE16) between the two specimens. In that series of tests, however, no localised temperature control over the specimens was possible and specimen temperature effects could only be assessed by interchanging their positions in the rig. The introduction of locally positioned auxilliary heaters permitted a degree of control over the specimen temperature difference. The effect of ΔT upon pitting and transfer of the PE16 and 20/25 was then assessed and is reported in this paper. The study confirmed that the pitting transfer process was dependent on the temperature difference between the two surfaces. The direction and size of the transfer/pitting effect was independent of the material. Under the particular set of conditions employed in the test, pitting occurred only when the magnitude of ΔT exceeded 20⁰C. At high ΔT the initial period of high friction was extended and was associated with the tendency for gross transfer and pitting. (author)

[en] This paper examines a variety of metal alloys useful as coverings for offshore structures to protect against the heavy corrosion present in the splash zone. The alloys are nickel-copper, cupro-nickel, stainless steel, titanium, aluminum, and steel. The general physical and corrosion characteristics for each alloy are presented. The method of attaching the covering to a structure and the extent of covering, partial or full, are discussed. Then, the alloys are compared in corrosion resistance, ease of construction and repairability, impact resistance, cost, and weight. The structure is assumed to be an offshore platform with a required full coverage area of 9290 square meters. A recommendation based upon the comparison is made as to the most suitable alloy and the method of application. It is concluded that cupro-nickel alloy 706 would provide cost effective corrosion resistance with full coverage of the submerged and splash zone area of an offshore platform

[en] Previous work on a series of experimental high-manganese reduced-activation austenitic stainless steels demonstrated that they have improved tensile properties relative to type 316 stainless steel in both the annealed and 20% cold-worked conditions. Steels were tested with an Fe-20Mn-12Cr-0.25C (in weight percent) base composition, to which various combinations of Ti, W, V, P, and B were added. Tensile tests have now been completed on these steels after thermal aging at 600 degrees C. Thermal stability varied with composition, but the alloys were as stable or more stable than type 316 stainless steel. the strength of the annealed steels increased slightly after aging to 5000 h, while a strength decrease occurred for the cold worked steel. In both conditions, a steel containing a combination of all the alloying elements was most stable and had the best strength after thermal aging 5000 h at 600 degrees C. Despite having much higher strength than 316 stainless steel after aging, the ductility of the strongest experimental alloy was still as good as that of 316 stainless steel

[en] A nitrogen-bearing austenitic stainless steel (Fe-18Cr-3Ni-13Mn-0.37N) was subjected to fatigue tests at 295 and 4 K. Sensitization (chromium carbo-nitride precipitation) was induced by heating the as-received annealed material for 0.75 or 1.5 h at 977 K. Data comparisons for the sensitized versus the annealed conditions indicate that at 295 K there is little or no difference in the Paris law parameters governing fatigue crack growth rates at intermediate ΔK. At 4 K, however, sensitization reduces the fatigue resistance of this steel by adversely affecting all three stages of the fatigue process: crack initiation, crack propagation, and fatigue fracture toughness

[en] In this paper the results of an investigation of the beam modification (erosion) of stainless steel are presented. The possible similarity of the martensitic stainless steel degradation for turbine engine blades and austenitic stainless steel used as a wall of the vacuum vessel for fusion reactor application has been pointed out. Changes appearing during the interaction have been investigated on the rotating turbine blade material. Simultaneously morphological changes of the 'target' and the change of shape of bombarding species have been analysed. (author)

[en] The metallography of duplex stainless steel castings was studied in a series of CF8M alloys with varying ferrite content. Various etching techniques were employed to facilitate microstructural characterization of primary and secondary structures by light microscopy. These observations were then correlated with transmission electron microscopy observations of substructure and selected area electron diffraction studies of the crystallography of the delta → γ transformation. All alloys possessed a significantly recovered dislocation substructure in both the γ and delta phases which was correlated with certain microstructural features. The crystallography of the delta → γ transformation was found to be consistent with a Kurdjumov-Sachs type orientation relationship regardless of apparent residual delta morphology. On the basis of these observations a model for the evolution of residual delta morphology was proposed

[en] This chapter examines lattice-distortive, virtually diffusionless structural changes having dominant deviatoric components and associated shape changes such that strain energy dominates the kinetics and morphology during the transformations. Nucleation restricts the martensitic transformation in all ferrous alloys and in some nonferrous systems. Topics considered include temperature dependence, time dependence, stress dependence, morphology and crystallography. The materials examined are austenitic stainless steels, alkali metals (sodium and lithium), solidified gases (hydrogen, oxygen, argon-nitrogen and argon-oxygen), superconductors (titanium-niobium, Nb₃Sn, other A15-structure superconductors), iron-nickel alloys, and polymers

[en] Stainless steel pipelines to be repaired as an in core structural component have minute defects such as corrosion cracks at the outer surface thereof. An inner tube for repair made of stainless steel is attached in close contact on the outer surface of the pipeline repaired so as to surround the defects. A shape memory alloy wires made of an alloy comprising 50% Ti, 47% Ni and 3% Fe are uniformly wound at the circumference of the inner tube. The shape memory alloy wires are put to 4% tensile working at a liquid nitrogen temperature compared with that at a room temperature, and they are wound at the outer circumference of the inner tube while keeping the liquid hydrogen temperature. Subsequently, they are left at a room temperature. Compression stresses are applied to the inner tube from the surroundings by the shrinkage of the shape memory alloy wires, so that the inner tube is strongly fixed to the pipelines to be repaired. The defects caused on the structural component can thus be repaired in a short period of time. In addition, it can be applied also to a structural component having a complicated configuration. (I.N.)

No abstract available

[en] A series of Fe-Cr-C and Fe-Ni-Cr-C steels have been processed by rapid solidification and ion implantation. Rapid solidifcation results in a fine grained structure leading to a significant suppression of the M_S (martensite start) temperature in all cases. By contrast, implantation with Sb⁺ ions of similar steels raises the M_S temperature as a consequence of the large excess vancany population. Rapid solidification of these alloys does not lead to amorphisation unless at least 12 at% of phosphorous is present. This contrasts significantly with the low P⁺ fluences (10¹⁶ ions cm^-2) that are necessary for the onset of amorphisation by implantation. (orig.)