Metallurgical Transactions A

, Volume 24, Issue 5, pp 1133–1141 | Cite as

Fracture toughness analysis of heat-affected zones in high-strength low-alloy steel welds

  • Sunghak Lee
  • Byung Chun Kim
  • Dongil Kwon
Mechanical Behavior
Received:

Abstract

This study is concerned with a correlation of fracture toughness with microstructural factors in heat-affected zones (HAZs) of a normalized high-strength low-alloy (HSLA) steel. In order to explain weld joint performance, tensile and plane strain fracture toughness tests were conducted for the simulated coarse-grained HAZ microstructures. The micromechanisms of fracture processes involved in void and microcrack formation are identified byin situ scanning electron microscopy (SEM) fracture observations and void initiation study. The fracture toughness results are also interpreted using simple fracture initiation models founded on the basic assumption that a crack initiates at a certain critical strain or stress developed over some microstructurally significant distance. The calculated KIc values are found to scale roughly with the spacing of the stringer-type martensite islands associated with voids, confirming that martensite islands play an important role in reducing the toughness of the coarse-grained HAZs. These findings suggest that the formation of martensite islands should be prevented by controlling the chemical compositions and by using the proper welding conditions to enhance fracture toughness of the welded joints of the HSLA steel.

Keywords

Martensite Fracture Toughness Double Cantilever Beam Specimen Void Initiation Martensite Island 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
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Copyright information

© The Minerals, Metals and Materials Society, and ASM International 1993

Authors and Affiliations

  • Sunghak Lee
    • 1
  • Byung Chun Kim
    • 2
  • Dongil Kwon
    • 3
  1. 1.Department of Materials Science and EngineeringCenter for Advanced Aerospace Materials, Pohang Institute of Science and TechnologyPohangKorea
  2. 2.POSCO HüLS Co., Ltd.ChonanKorea
  3. 3.Department of Materials Science and EngineeringChangwon National UniversityChangwonKorea

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