The erosion of gun barrels results from combined chemical-thermal-mechanical action of propellant gases on the gun bore. The rate of the erosion is too great for corrosion by normal gaseous species. It is likely that transient, energetic species including free radicals, such as atomic hydrogen, atomic nitrogen and carbon- or oxygen containing radicals, are the active species that chemically alter the gun bore. Partially dissociated (by a microwave discharge) hydrogen, nitrogen, and methane were allowed to react with 4340 steel strips heated to 400-900 Cel. While undissociated gases at low pressures (approx. 1 torr) were found to have negligible effect other than those due to heat treatment, atomic free radicals were highly reactive at steel temperatures ranging from 600 to 900 Cel. At 600 Cel atomic hydrogen removed carbon from surface layers and at 900 Cel bulk decarburization was rapid. Surface hardness decreased with carbon removal and the microstructure was observed to change from martensite to ferrite with increasing decarburization. Microwave dissociation of a 3 % CH4-helium mixture was found to case-carburize the steel strips. Similarly, dissociated nitrogen nitrided the steel. (Jensen)
Effect of transient combustion species on 4340 steels
Wirkung einer Schnellverbrennung besonderer Art auf 4340-Staehle
US Government Research Reports ; May ; 1-42
1979
42 Seiten
Report
Englisch
EROSION , BOHRLOCH , TEMPERATUR , AUFKOHLEN , KORROSION , VERSCHLEISS , WASSERSTOFF , STICKSTOFF , ENTKOHLEN , HAERTE , MARTENSIT , DISSOZIATION , ENTKOHLUNGSGESCHWINDIGKEIT , NITRIEREN (HAERTEN)
DataCite | 1928
Effect of Hydrogen on the Mechanical Behavior of AISI 4340 and SA372 Steels
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