Title

EFFECTS OF ALLOYING ON THE MICROSTRUCTURE, INCLUSION FORMATION AND TOUGHNESS OF HSLA MULTIPASS WELDS

EFFECTS OF ALLOYING ON THE MICROSTRUCTURE, INCLUSION FORMATION AND TOUGHNESS OF HSLA MULTIPASS WELDS

Authorship

FILHO, WALDEK WLADIMIR BOSE; STRANGWOOD, MARTIN

FILHO, WALDEK WLADIMIR BOSE

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STRANGWOOD, MARTIN

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DOI

10.5151/2594-5327-C00260-4038-4058

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Abstract

The effects of Ti, Ni, Mo and Cr on microstructural development and the chemical composition of the non-metallic inclusions, in high strength low alloy multipass (HSLA) weld metal have been considered. Increasing titanium content in the range of 50 to 400 ppm, has not caused any major effects on microstructural development. With a further increase on the hardenability, by Ni, Mo and Cr additions, has changed the microstructure from a mixture of allotriomorphic ferrite, Widmanstätten ferrite, acicular ferrite and microphases to a mixture of acicular ferrite, bainite, low carbon martensite and microphases. In weld metals with low titanium content, manganese and silicon were the main chemical elements present in inclusions. Increasing the titanium content in the weld metal leads to an increase in the titanium content of the inclusions, and for a very high titanium content, ≈700 ppm, the amount of titanium in the inclusions varies in the range of 60 to 70 wt.%. Increasing the hardenability has led to a loss in toughness, and the COD value in the upper shelf has dropped drastically.

The effects of Ti, Ni, Mo and Cr on microstructural development and the chemical composition of the non-metallic inclusions, in high strength low alloy multipass (HSLA) weld metal have been considered. Increasing titanium content in the range of 50 to 400 ppm, has not caused any major effects on microstructural development. With a further increase on the hardenability, by Ni, Mo and Cr additions, has changed the microstructure from a mixture of allotriomorphic ferrite, Widmanstätten ferrite, acicular ferrite and microphases to a mixture of acicular ferrite, bainite, low carbon martensite and microphases. In weld metals with low titanium content, manganese and silicon were the main chemical elements present in inclusions. Increasing the titanium content in the weld metal leads to an increase in the titanium content of the inclusions, and for a very high titanium content, ≈700 ppm, the amount of titanium in the inclusions varies in the range of 60 to 70 wt.%. Increasing the hardenability has led to a loss in toughness, and the COD value in the upper shelf has dropped drastically.

Keywords

HSLA welds, microstructure, toughness, alloying elements, inclusions

HSLA welds, microstructure, toughness, alloying elements, inclusions