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Sample records for alloy-in-738

  1. Evaluation of property scatter of Ni-base alloy in 738 LC

    International Nuclear Information System (INIS)

    Highlights: → Correlation between chemical composition and position in scatter band. → Substantial influence of micro porosity. → Hot isostatic pressing (HIP) reduces scatter significantly. → Property scatter diminishes with rising temperature. - Abstract: In high temperature creep testing the conventionally cast alloy IN 738 LC exhibits a comparably large property scatter which requires high safety margins in design and dimensioning and subsequently causes an incomplete exploitation of the materials potential. The reasons for this property scatter were investigated and traced back to different influencing factors. Parallel to investigations on the microstructure of post-exposure material and conventional scatter band analysis, artificial neural networks were successfully applied to discover relations between the chemical composition of the individual melt and the position of the corresponding test results within the global scatter band.

  2. Effects of temperature and Al-concentration on formation mechanism of an aluminide coating applied on super alloy IN738LC through a single-step high activity gas diffusion process

    International Nuclear Information System (INIS)

    Formation mechanism of an aluminide coating on a nickel base superalloy IN738LC via a single step high activity gas diffusion process has been investigated in this research. Effects of coating temperature and aluminum concentration in powder mixture on formation mechanism were studied using optical and scanning electron microscopes, energy-dispersive X-ray spectroscopy and X-ray diffraction techniques. For this purpose two different packs containing 1 and 2 wtpercentaluminum powder, were used for coating the samples at two temperatures, 850degreeC and l050degreeC. The ratio of Al to activator was kept constant in both packs. By increasing the Al content in high activity powder mixture, the concentration of diffused Al increased in the coating layers, and the thickness of coating increased. At 1050degreeC as the rate of diffused Al to the interdiffusion zone increased, this zone gradually transformed to outer coating phases. At 850degreeC coating formed by inward diffusion of Al, but at 1050degreeC it was initially formed by inward diffusion of Al followed by outward diffusion of Ni.

  3. Influence of different etchants on the representation of microstructures in nickel alloys; Einfluss verschiedener Aetzmittel auf die Gefuegedarstellung in Nickellegierungen

    Energy Technology Data Exchange (ETDEWEB)

    Speicher, Magdalena; Scheck, Rudi; Maile, Karl [Stuttgart Univ. (Germany). Materialpruefungsanstalt

    2016-04-15

    This work presents a comparison of selected nickel alloys of the same condition which were treated by means of specifically chosen etching techniques. Microstructures on microscope images of wrought Alloy 617, a casting variant of Alloy 625, a polycrystalline casting alloy IN-738 LC, as well as of a monocrystalline superalloy CM 247 LC SX, respectively, are juxtaposed and evaluated. This approach allows for a comprehensive optical microscopy characterization of the characteristic microstructural features.

  4. Influence of different etchants on the representation of microstructures in nickel alloys

    International Nuclear Information System (INIS)

    This work presents a comparison of selected nickel alloys of the same condition which were treated by means of specifically chosen etching techniques. Microstructures on microscope images of wrought Alloy 617, a casting variant of Alloy 625, a polycrystalline casting alloy IN-738 LC, as well as of a monocrystalline superalloy CM 247 LC SX, respectively, are juxtaposed and evaluated. This approach allows for a comprehensive optical microscopy characterization of the characteristic microstructural features.

  5. Corrosion testing of nickel base superalloys and coatings with molten sulphates at 9000C

    International Nuclear Information System (INIS)

    The work refers to the application of electrochemical testing procedures on the corrosion properties of different commercial nickel base superalloys. This included the following alloys: IN 738 LC, IN 939, Nimonic 81, Nimonic 90, IN 713 LC, IN 792 5 A, IN 100, IN 853, IN 617, Nimonic 105, B 1925, N 33 Hastelloy X, Mar M 246, Mar M 421, Mar M 432, IN 671, Nicrofer 7520, IN 800. Beside a short galvanostatic test with subsequent metallographic measurement of the resulting corrosion damage, potential/current density curves and potential/time curves were taken from selected alloys. In all cases the corrodent was a melt of (Nasub(0.9), Ksub(0.1))2SO4 at 9000C. Thermogravimetric tests were run for comparison of three alloys (IN 738 LC, IN 939, IN 713 LC). The existence of ranges of passivation and induction periods could be established. The galvanostatic corrosion test was also applied to the testing of two different coatings (S 57 and LDC2) on IN 738 LC and Mar M246 or IN 100. In all cases scale compounds and intermetallics in coatings were analyzed by XRD. The electrochemical test for nickel base superalloys is a useful tool for a quick ranking of alloys. For the assessment of coatings more work will be necessary. (orig.)

  6. Microstructural changes induced by grinding of Ni-base superalloy IN 738 LC and their relationship to machining parameters

    International Nuclear Information System (INIS)

    Subsurface microstructures, which have been produced by grinding of the nickel-base alloy IN738LC, were examined with TEM after preparation of suitable cross-sections. Two types of superficial zones were observed, namely a deformation induced type 1 and a thermally affected type 2 microstructure. The latter one consisted of a serveral microns thick γ'-depleted zone. It could be shown by estimating temperature gradients and flash temperatures, that grinding with corundum wheels can cause local melting at contact spots, thus leading to the observed γ'-depleted zone at the surface. The thickness of this zone was a linear function of grinding energy for a given grinding wheel specification. If the heat conductivity of the grinding wheel material is much higher than the one of the workpiece material, as is the case for cubic boron nitride (CBN), flash temperatures are considerably reduced, so that local melting cannot occur. Since local melting can be regarded as a prerequisite to the initiation of deep cracks, grinding with CBN wheels seems to be a promising alternative in manufacturing the root profiles of turbine blades. (orig.)

  7. Thermo-mechanical fatigue behaviour of the near-{gamma}-titanium aluminide alloy TNB-V5 under uniaxial and multiaxial loading

    Energy Technology Data Exchange (ETDEWEB)

    Brookes, Stephen Peter

    2009-12-19

    -strain history. The effects of TMF on the microstructure were also investigated. For all types of tests intergranular fracture is predominant. Failure is strongly influenced by environmental conditions. This study compares TMF results of TiAl with previous TMF investigations on the nickel-based alloys IN 738 and Nimonic 90. IN 738 shows similar TMF behaviour to {gamma}-TiAl in that uniaxial IP loading has the longest fatigue lifetimes. Nimonic 90 shows the opposite behaviour to both of these alloys. A lifetime model developed for this near-{gamma}-TiAl alloy, successfully describes all temperaturestrain TMF loading conditions over the test temperature range, with the use of a single loading parameter. The loading parameter is based on the plastic work per cycle, and is not only dependant on the mean tensile stress but also on the maximum principal stress. The loading parameter responds to various strain-temperature-paths differently. It describes the lifetime relation between uniaxial IP and OP loading, axial and torsional loading and the hold period effect. (orig.)