Accession Number : ADA137971

Title :   Analysis of Microstructure and Strengthening Mechanisms in Laser Surface Alloyed Fe-Cr and Fe-C-Cr Alloy Systems.

Descriptive Note : Final rept. 8 Jul 80-31 Oct 83,


Personal Author(s) : Wood,W E

PDF Url : ADA137971

Report Date : 22 Dec 1983

Pagination or Media Count : 29

Abstract : The effects of rapid melting and subsequent quenching on the solidification behavior and solid state transformation structures of laser surface alloyed Fe-Cr, Fe-Ni, Fe-Cr-Ni and Fe-C-Cr systems were investigated as functions of composition (0-50%Cr, 0-20%Ni, 0-20%Cr/Ni, 0-1C%) and cooling rate. The microstructures were characterized by optical, scanning and thin foil transmission electron microscopy. The effects of laser parameters (laser power, beam size and scan rate) and coating variables (composition, thickness and morphology) on the penetration depth and melt width were also evaluated. The microstructures of Fe-Cr alloys were ferritic in nature, irrespective of the composition (0-50%Cr) and cooling rate. The transformation structures of Fe-5%Ni and Fe-6%Cr-2%Ni alloys exhibited a mixture of martensite and ferrite. The transformation structures of Fe-C-Cr alloys were studied as functions of the carbon (0.2-1.0%C) and chromium contents (0-40%Cr). The rapid solidification effects including the retention of supersaturated austenite, lack of carbide precipitation and the morphology of phases are discussed as functions of alloy content and cooling rate.

Descriptors :   *Alloys, *Chromium alloys, *Iron alloys, *Carbon alloys, *Solidification, *Melting, *Quick reaction, *Laser beams, Structural analysis, Microstructure, Solid state physics, Strength(Mechanics), Mechanical properties, Grain size, Phase transformations, Austenite, Martensite, Morphology, Precipitation, Thickness, Coatings, Thin films, Metastable state, Distortion

Subject Categories : Physical Chemistry
      Lasers and Masers
      Properties of Metals and Alloys

Distribution Statement : APPROVED FOR PUBLIC RELEASE