Accession Number:

ADA242937

Title:

Microstructure and Mechanical Properties of HSLA-100 Steel

Descriptive Note:

Master's thesis,

Corporate Author:

NAVAL POSTGRADUATE SCHOOL MONTEREY CA

Personal Author(s):

Report Date:

1990-12-01

Pagination or Media Count:

79.0

Abstract:

Light microscopy, scanning electron microscopy, and transmission electron microscopy were employed to examine the microstructural basis for the mechanical properties of as-quenched and tempered HSLA-100 steel. Examination of the alloy revealed granular bainite with martensite and retained austenite in the as-quenched state which upon aging at temperatures below the lower transformation temperature, 677 C, formed tempered bainite with precipitates of copper and carbides. These results indicate the strength and toughness of HSLA- 100 steel aged below 677 C is based primarily on the fine prior austenite grain size and classic copper precipitation behavior but also on the bainite dislocation substructure and carbides. After tempering at 677 C, HSLA-100 steel has a dual-phase microstructure consisting of bainitic ferrite laths, fine ferrite grain clusters and martensite with precipitates of carbides and overaged copper. The results indicate the yield strength of the overaged alloy is based on the fine ferrite grain and bainite lath sizes, the fine carbide distribution and elastic moduli strengthening while the toughness is the result of the high- angle ferrite grain boundaries, the fine intralath carbides and the ductile overaged copper precipitates.

Subject Categories:

  • Properties of Metals and Alloys
  • Fabrication Metallurgy
  • Marine Engineering

Distribution Statement:

APPROVED FOR PUBLIC RELEASE