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[en] Orifices or ferrules are used to stabilise the flow in parallel paths in boilers. While they must have the right pressure drop characteristics, they must also neither suffer corrosion themselves nor induce corrosion elsewhere. Orifice geometries are also useful specimens for examining corrosion under a range of well defined hydrodynamic mass transfer conditions. This paper describes a number of projects both examining service experience of orifice plates used in AGR plants and the experimental use of orifice assemblies, from the corrosion standpoint. Important findings include: (1) The satisfactory behaviour of sharp edged thin orifice plates, made of a 16Cr 2Ni martensitic stainless steel, in service up to 20,000 hours. (2) The clear difference between the lack of deposition on orifice plates in service and the severe deposition in rig studies. (3) The reduced erosion-corrosion rates of the alloy steels; improvement factors of 15X for 1Cr 1/2Mo 25X for 2 1/4Cr 1Mo and 33X for 9Cr 1Mo as compared to mild steel, being obtained. (4) That while hydrodynamic factors are undoubtedly important in relation to diffusion controlled corrosion reactions, rates are not always simply related to the mass transfer rate

[en] The most recent information on the topic of reheat cracking in low alloy constructional steels, ferritic creep resisting steels, nickel-base alloys and austenitic stainless steels is summarised. Attention is paid to reheat cracking in weld metal, underclad cracking, the mechanism of reheat cracking and test methods. From the literature review it appears that there is still a considerable research effort being spent on the topic of reheat cracking although the problem of reheat cracking in practice has largely been solved. (author)

[en] The report contains the material data sheets and design formulae of the cladding materials and structural materials of the core area to be used in the design of the third core of KNK II. The data are given for the materials 1.4970 kv (X10CrNiMoTiB 15 15), 1.4914 (X10CrMoVNb 11 1), 1.4980 (= A286 = X5 NiCrTi 26 15), RGTX2 KV (X10NiCrMoTiB 25 10) and INCONEL 718 (Ni Cr 19NbMo)

[en] The characteristics of the irradiation embrittlement of some ferritic stainless steels were examined by tensile tests. Steels selected in this investigation were classified into three groups: chi phase, precipitation hardened Fe-13Cr steels; tempered martensitic Fe-12Cr steels; and low alloy steels. The latter steels were chosen in order to compare the irradiation embrittlement characteristics with those of stainless steels. The stainless steels were superior to the low alloy steels with regard to the irradiation embrittlement (the changes in both ductile-brittle transition temperature (DBTT) and unstable plastic flow transition temperature (UPFTT)), irrespective of whether these stainless steels had chi phase precipitated structures or tempered martensitic structures. The suppression of the DBTT increase owing to irradiation results from low yield stress increase Δσsub(y) and high |[dσsub(y)(u)/dT]|, where u denotes unirradiated, in the stainless steels. The suppression of the UPFTT results from the high work hardening rate or the high work exponent and the low Lueders strain in the stainless steels. These characteristics of irradiation embrittlement in the ferritic stainless steels are thought to be caused by the defect structure, which is modified by Cr atoms. (author)

[en] New grades of ferritic-austenitic duplex and superduplex stainless have been an attractive combination of mechanical and corrosion properties and are thus suitable for many applications. This paper covers aspects of metallurgical weldability and welding technology. The paper presents an overview of ferritic-austenitic stainless steels with particular emphasis on physical metallurgy, mechanical and corrosion properties and metallurgy of welding. Basic welding procedures including joint preparation, limitation of heat input and interpass temperature and effect of shielding gases are described. (author). 10 refs, 3 figs, 10 tabs

[en] The compositional dependence of the Neel temperature has been studied, from data derived by different techniques and by various authors, for 30 austenitic stainless steels or special Fe-Cr-Ni alloys whose compositions fall near the range of the AISI 300 series. A linear relationship enables the predicted Neel temperature, Tsub(N) to be evaluated with an rms deviation of 3.5 K on the basis of the wt% of alloy constituents. The effect of alloying elements in lowering the calculated value, T*sub(N), increases in the order Ci, Ni, Mo, and Si, while Mn is unique in raising T*sub(N). By comparing this equation for T*sub(N) with previous equations to predict the onset of a martensitic phase change at a temperature Msub(s), it is concluded that isotherms for Msub(s) in ternary Fe-Cr-Ni alloys should also be parallel to the tangent to the boundary between fcc and bcc phases calculated from thermodynamic data. This conclusion is discussed with reference to results obtained by other workers. The significance of the results is discussed in terms of the application of stainless steel in magnetic environments at low temperatures. (author)

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