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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Characteristics and mechanisms of hydrogen-induced quasi-cleavage fracture of lath martensitic steel

Here this study presents an in-depth characterization of the microstructures, crystallographic orientations, and dislocation characteristics beneath hydrogen-induced quasi-cleavage fracture features of an as-quenched, lath martensitic (α') 22MnB5 steel. The fracture surfaces of gaseous hydrogen-embrittled martensitic specimens were analyzed by a combination of multiple analytical tools: scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), transmission electron microscopy (TEM), and transmission Kikuchi diffraction (TKD). The dominant fracture mode in the hydrogen-affected zones was quasi-cleavage fracture, which involved significant plasticity, evidenced by plastic zones near tear ridges and a high density of dislocations beneath the quasi-cleavage facets. The martensite constituent sizes, variant orientations, and boundaries influenced the quasi-cleavage surface morphologies. Fractography revealed the occurrence of {100} α' -type cleavage across martensitic laths, developing relatively “flat” quasi-cleavage surfaces, in addition to {110} α' -type cracking likely along lath and block boundaries, and fracture along non-cleavage planes. The likelihood of the formation of the relatively “flat” quasi-cleavage surfaces increased with increasing martensitic constituent sizes. Substantial dislocation bands formed on intersecting {112} α' slip planes within a martensite block below the hydrogen-induced cleavage fractures on {100} α' planes. River markings on the quasi-cleavage surfaces were found to originate from the complex, hierarchical lath martensitic microstructure. Steps and ridges on the quasi-cleavage facets generally linked with the various martensitic boundaries, suggesting that they were produced as a result of crack deviations at those boundaries. The fracture paths and martensite quasi-cleavage mechanisms are discussed in the context of the role of hydrogen and Cottrell cleavage model.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Precitech N200 Lathe Refurbish/Upgrade Project [Slides]

Background: LANL purchased two Precitech N200 Lathes in 2002; Machines were modified for glovebox operations; First lathe became operational in 2009; After nearly 15 years of continuous operation, electric components have started to fail; Precitech has been refurbishing N200 lathes for other 20 years; Existing lathes in PF-4 needed for surveillances/certification missions; after training at Precitech, LANL workers will perform refurbishment/upgrade tasks in PF-4.

42 ENGINEERING↗
NASA NTRS1966

Tool post modification allows easy turret lathe cutting-tool alignment

Modified tool holder and tool post permit alignment of turret lathe cutting tools on the center of the spindle. The tool is aligned with the spindle by the holder which is kept in position by a hydraulic lock in feature of the tool post. The tool post is used on horizontal and vertical turret lathes and other engine lathes.

Fouts, L.↗
NASA NTRS1964

Lathe converted for grinding aspheric surfaces

A standard overarm tracing lathe converted by the addition of an independently driven diamond grinding wheel is used for grinding aspheric surfaces. The motion of the wheel is controlled by the lathe air tracer following the template which produces the desired aspheric profile.

Larmer, J. W.↗
NASA NTRS1966

Lathe chuck key incorporates safety feature

Lathe chuck key with spring loaded plunger cannot inadvertently be left in the chuck when the lathe is started. The plunger automatically ejects the key from the chuck when hand pressure is released.

Christman, G. L.↗
NASA NTRS1966

Swiveling Lathe Jaw Concept for Holding Irregular Pieces

Clamp holds irregularly shaped pieces in lathe chuck without damage and eliminates excessive time in selecting optimum mounting. Interchangeable jaws ride in standard jaw slots but swivel so that the jaw face bears evenly against the workpiece regardless of contour. The jaws can be used on both engine and turret lathes.

David, J.↗
NASA NTRS1982

Lathe Attachment Finishes Inner Surface of Tubes

Extremely smooth finishes are machined on inside surfaces of tubes by new attachment for a lathe. The relatively inexpensive accessory, called a "microhone," holds a honing stone against workpiece by rigid tangs instead of springs as in conventional honing tools. Inner rod permits adjustment of microhoning stone, while outer tube supports assembly. Outer tube is held between split blocks on lathe toolpost. Microhoning can be done with either microhone or workpiece moving and other member stationary.

Lancki, A. J.↗
DOE OSTI2026

Metastable formation and disordering kinetics of body-centered orthorhombic CrNi 2 laths in a Cr-Ni binary alloy

Chromium (Cr) alloys combine low density with high-temperature strength but suffer from brittleness and rapid softening. Body-centered orthorhombic (BCO) CrNi 2 laths have been shown to improve Cr-alloy high-temperature strength retention, yet their thermal stability and transformation behavior remain unclear. CrNi 2 conventionally forms through long-range ordering from a face-centered cubic (FCC) phase. Using multiscale microscopy and neutron diffraction, we show that CrNi 2 instead nucleates from a body-centered cubic (BCC) matrix, in a binary Cr 85 Ni 15 alloy. Despite aging above the equilibrium ordering temperature, CrNi 2 persists for ∼220 h at 760 °C before fully disordering, indicating sluggish transformation kinetics. The formation and decomposition follow differing transformation pathways (BCC → CrNi 2 → FCC), revealing kinetic asymmetry not captured by equilibrium Cr-Ni phase diagrams. In conclusion, these findings redefine the transformation behavior of CrNi 2 , establish its metastable kinetic window, and suggest alloying strategies to stabilize CrNi 2 for precipitation strengthening of high-temperature Cr-alloys.

CrNi2 transformation kinetics↗
NASA NTRS1965

Lathe attachment used to machine elliptical cones

Close-tolerance elliptical cones are fabricated by cutting-tool guide assembly used with conventional tracer cartridge on turret lathe accurately produced in two machine operations.

Allen, J. H., Sr.↗
NASA NTRS1965

Self-aligning fixture used in lathe chuck jaw refacing

Self-aligning tool positions and rigidly holds lathe chuck jaws for refacing and truing of the clamping surface. The jaws clamp the fixture in the manner of clamping a workpiece. The fixture can be modified to accommodate four-jawed checks.

Linn, C. C.↗
NASA NTRS1972

Lathe tool bit and holder for machining fiberglass materials

A lathe tool and holder combination for machining resin impregnated fiberglass cloth laminates is described. The tool holder and tool bit combination is designed to accommodate a conventional carbide-tipped, round shank router bit as the cutting medium, and provides an infinite number of cutting angles in order to produce a true and smooth surface in the fiberglass material workpiece with every pass of the tool bit. The technique utilizes damaged router bits which ordinarily would be discarded.

Winn, L. E.↗
NASA NTRS2009

Trajectory Calculator for Finite-Radius Cutter on a Lathe

A computer program calculates the two-dimensional trajectory (radial vs. axial position) of a finite-radius-of-curvature cutting tool on a lathe so as to cut a workpiece to a piecewise-continuous, analytically defined surface of revolution. (In the original intended application, the tool is a diamond cutter, and the workpiece is made of a crystalline material and is to be formed into an optical resonator disk.) The program also calculates an optimum cutting speed as F/L, where F is a material-dependent empirical factor and L is the effective instantaneous length of the cutting edge.

Savchenkov, Anatoliy↗
NASA NTRS2018

Lath Structured Monazite from Haughton Dome, Canada Reveals Shock-Induced Tetragonal High Pressure Polymorph of REEPO4

Shock deformed monazite, mono-clinic rare earth element (REE) phosphate, from the Haughton Dome impact structure, Nunavut, Canada, contain lath-structured lamellae. Microstructural phase heritage indicate the former presence of a previously unreported, shock-produced, tetragonal-structured, high pressure polymorph of REEPO4. This study presents an electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) study of shock deformed monazite from the historic sample DIG-9, a shock stage III, biotite sillimanite gneiss sample from near the central uplift of the Haughton Dome (75°22'20"N, 89°40'50"W), in which shock features in monazite were first described.

Erickson, T. M.↗
DOE OSTI2020

Materials Data on LaTh by Materials Project

ThLa crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are two inequivalent Th sites. In the first Th site, Th is bonded to six equivalent Th and six La atoms to form ThLa6Th6 cuboctahedra that share corners with twelve ThLa6Th6 cuboctahedra, edges with twelve ThLa6Th6 cuboctahedra, edges with twelve LaLa6Th6 cuboctahedra, faces with six equivalent ThLa6Th6 cuboctahedra, and faces with twelve LaLa6Th6 cuboctahedra. All Th–Th bond lengths are 3.61 Å. All Th–La bond lengths are 3.65 Å. In the second Th site, Th is bonded to ten equivalent Th and six La atoms to form ThLa6Th10 cuboctahedra that share corners with ten LaLa6Th6 cuboctahedra, corners with twelve ThLa6Th6 cuboctahedra, edges with eight LaLa6Th6 cuboctahedra, edges with sixteen ThLa6Th6 cuboctahedra, faces with sixteen equivalent ThLa6Th10 cuboctahedra, and faces with eighteen LaLa6Th6 cuboctahedra. There are a spread of Th–Th bond distances ranging from 3.61–7.23 Å. All Th–La bond lengths are 3.65 Å. There are three inequivalent La sites. In the first La site, La is bonded to six equivalent Th and six equivalent La atoms to form LaLa6Th6 cuboctahedra that share corners with twelve LaLa6Th6 cuboctahedra, edges with twelve equivalent ThLa6Th6 cuboctahedra, edges with twelve LaLa6Th6 cuboctahedra, faces with six equivalent LaLa6Th6 cuboctahedra, and faces with twelve equivalent ThLa6Th6 cuboctahedra. All La–La bond lengths are 3.61 Å. In the second La site, La is bonded to six Th and six equivalent La atoms to form LaLa6Th6 cuboctahedra that share corners with five equivalent ThLa6Th10 cuboctahedra, corners with twelve LaLa6Th6 cuboctahedra, edges with ten ThLa6Th6 cuboctahedra, edges with twelve LaLa6Th6 cuboctahedra, faces with six equivalent LaLa6Th6 cuboctahedra, and faces with fifteen ThLa6Th6 cuboctahedra. All La–Th bond lengths are 3.65 Å. All La–La bond lengths are 3.61 Å. In the third La site, La is bonded to six Th and six equivalent La atoms to form LaLa6Th6 cuboctahedra that share corners with five equivalent ThLa6Th10 cuboctahedra, corners with twelve LaLa6Th6 cuboctahedra, edges with ten ThLa6Th6 cuboctahedra, edges with twelve LaLa6Th6 cuboctahedra, faces with six equivalent LaLa6Th6 cuboctahedra, and faces with fifteen ThLa6Th6 cuboctahedra. All La–La bond lengths are 3.61 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Investigation of Carbide Inclusions in Cast Uranium [Slides]

Outline - Introduction: The motivations for the project, and some background on inclusions in uranium, and about the samples; Lath Inclusion Morphology: Looking at the morphology of a specific family of carbide inclusions in casting 20; Clustering of Lath Inclusions: Investigating the group behavior of these lath shaped inclusions from the inner to outer edges; Conclusions: Final thoughts on the lath inclusions and future work ideas.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2020

Microstructure–Property Correlation in a Laser Powder Bed Fusion Processed High-Strength AF-9628 Steel

Laser powder bed fusion additive manufacturing (LPBF-AM) of a low-alloy, high-performance AF-9628 steel results in exceptionally high strength and good ductility. The reasons for such mechanical properties are investigated through detailed microscopy performed at several length scales. Thus, the characterization of melt pool, porosity, grain morphology, phases, and dislocations is performed in the as-printed material. The as-printed material consists of only 0.004 vol% of uniformly distributed porosity, single-phase martensitic laths with an average lath size of ≈2.5 μm, the absence of carbides indicating interstitial trapping of C atom, and high dislocation density in the martensitic laths. Experimental data through microscopy are then fed in analytical models for calculating strengthening contributions from various strengthening mechanisms. Calculated yield strength agrees well with experimentally determined value, and therefore, activation of various strengthening mechanisms is established in as-printed AF-9628.

36 MATERIALS SCIENCE↗