Effect of carbon on the microstructure and mechanical properties of all weld metal from an E7024 SMAW electrode
- and others
The objective of this work was to study the effect of the carbon content on the microstructure and the mechanical properties of the all weld metal deposited by an E 7024 manual electrode, and in this way to increase the knowledge about the metallurgy of deposited metals of rutile electrodes. Four E7024 electrodes, 3.25 mm diameter, were prepared with the addition of graphite to the coating, to obtain in the all weld metal nominal carbon contents of 0.03, 0.06, 0.10, and 0.13%. The mechanical properties measured were: tensile properties at room temperature and Charpy impact toughness over the temperature range from 20{degrees}C down to -70{degrees}C. Microstructure was examined and quantified on metallographic sections normal to the welding direction and obtained from the all-weld metal assemblies. As the graphite content of the electrode coating increases, it was found that: (1) In the all-weld metal, the carbon content increases, the oxygen one decreases and the manganese and silicon contents remain constant. (2) The yield and tensile strengths increase, and it is necessary to have at least 0.06% of carbon in the deposited metal to obtain the minimum values required by the AWS standard. (3) The microstructure becomes finer. The primary austenitic grain size in the columnar region of the top bead decreases as well as the fine grain size of the refined region. (4) There is an increase in the hardness, measured along the vertical centerline of the all-weld metal specimens. By fixing the chemical composition of the weld metal, of rutile electrodes, it is possible to improve the mechanical properties to be able to use them in more exigent applications, taking advantage of all the technological characteristics of this type of electrodes.
- OSTI ID:
- 115500
- Report Number(s):
- CONF-9404233--
- Country of Publication:
- United States
- Language:
- English
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