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Results for “C-Mn”

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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5 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Environment enhanced fatigue crack propagation in metals: Inputs to fracture mechanics life prediction models

This report is a critical review of both environment-enhanced fatigue crack propagation data and the predictive capabilities of crack growth rate models. This information provides the necessary foundation for incorporating environmental effects in NASA FLAGRO and will better enable predictions of aerospace component fatigue lives. The review presents extensive literature data on 'stress corrosion cracking and corrosion fatigue.' The linear elastic fracture mechanics approach, based on stress intensity range (Delta(K)) similitude with microscopic crack propagation threshold and growth rates, provides a basis for these data. Results are presented showing enhanced growth rates for gases (viz., H2 and H2O) and electrolytes (e.g. NaCl and H2O) in aerospace alloys including: C-Mn and heat treated alloy steels, aluminum alloys, nickel-based superalloys, and titanium alloys. Environment causes purely time-dependent accelerated fatigue crack growth above the monotonic load cracking threshold (KIEAC) and promotes cycle-time dependent cracking below (KIEAC). These phenomenon are discussed in terms of hydrogen embrittlement, dissolution, and film rupture crack tip damage mechanisms.

Gangloff, Richard P.↗
NASA NTRS1994

Fatigue crack growth under variable amplitude loading

Fatigue crack growth tests were conducted on an Fe 510 E C-Mn steel and a submerged arc welded joint from the same material under constant, variable, and random loading amplitudes. Paris-Erdogan's crack growth rate law was tested for the evaluation of m and C using the stress intensity factor K, the J-integral, the effective stress intensity factor K(sub eff), and the root mean square stress intensity factor K(sub rms) fracture mechanics concepts. The effect of retardation and residual stresses resulting from welding was also considered. It was found that all concepts gave good life predictions in all cases.

Sidawi, Jihad A.↗
DOE OSTI2020

Materials Data on Mn7C3 by Materials Project

Mn7C3 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are five inequivalent Mn sites. In the first Mn site, Mn is bonded in a distorted trigonal non-coplanar geometry to three C atoms. There are one shorter (1.98 Å) and two longer (2.02 Å) Mn–C bond lengths. In the second Mn site, Mn is bonded in a distorted water-like geometry to two equivalent C atoms. Both Mn–C bond lengths are 2.01 Å. In the third Mn site, Mn is bonded in a distorted trigonal planar geometry to three C atoms. There is two shorter (1.96 Å) and one longer (1.97 Å) Mn–C bond length. In the fourth Mn site, Mn is bonded in a 3-coordinate geometry to three C atoms. There is one shorter (1.93 Å) and two longer (1.98 Å) Mn–C bond length. In the fifth Mn site, Mn is bonded in a 2-coordinate geometry to four C atoms. There are a spread of Mn–C bond distances ranging from 2.00–2.43 Å. There are two inequivalent C sites. In the first C site, C is bonded in a 6-coordinate geometry to seven Mn atoms. In the second C site, C is bonded in a 6-coordinate geometry to eight Mn atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mn5C2 by Materials Project

Mn5C2 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are three inequivalent Mn sites. In the first Mn site, Mn is bonded in a 2-coordinate geometry to three equivalent C atoms. There are two shorter (1.97 Å) and one longer (2.23 Å) Mn–C bond lengths. In the second Mn site, Mn is bonded to four equivalent C atoms to form distorted edge-sharing MnC4 tetrahedra. There are two shorter (2.01 Å) and two longer (2.03 Å) Mn–C bond lengths. In the third Mn site, Mn is bonded in a bent 150 degrees geometry to two equivalent C atoms. There is one shorter (1.98 Å) and one longer (2.01 Å) Mn–C bond length. C is bonded in a 7-coordinate geometry to seven Mn atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mn23C6 by Materials Project

Mn23C6 crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. there are four inequivalent Mn sites. In the first Mn site, Mn is bonded in a distorted cuboctahedral geometry to twelve equivalent Mn atoms. All Mn–Mn bond lengths are 2.46 Å. In the second Mn site, Mn is bonded in a distorted tetrahedral geometry to four equivalent Mn atoms. All Mn–Mn bond lengths are 2.38 Å. In the third Mn site, Mn is bonded in a trigonal non-coplanar geometry to one Mn and three equivalent C atoms. All Mn–C bond lengths are 2.06 Å. In the fourth Mn site, Mn is bonded in a bent 150 degrees geometry to one Mn and two equivalent C atoms. Both Mn–C bond lengths are 2.07 Å. C is bonded in a 8-coordinate geometry to eight Mn atoms.

36 MATERIALS SCIENCE↗