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Surface 3 of alloy AA6111-T4, even deeper into the weld material, showed similar results.Finally, we note that we did not perform a complete investigation of the base metal. However, some preliminary results indicate that the 6111 base metal had a much stronger texture than the 5182. This difference could be another reason why the 6111 material had a stronger texture in the columnar grain region of the weld.From these results, we can conclude that a strong cube texture forms in laser-welded AA5182-O and AA6111-T4 alloys and that the strength of the texture depends on the particular alloy and the depth through the weld zone. In particular, we note that the columnar grains that form on either side of the weld centerlines and appear to grow out from the parent metal into the liquid are highly textured, with a Ͻ001Ͼ direction parallel to the growth direction. This result is in agreement with studies of solidification in aluminum alloys that reported that a cube direction is a preferred growth direction. [15] Given that mechanical properties are strongly dependent on texture, [16] one would expect this texture could have a strong effect on the local mechanical response of the welds.The authors thank R. Mishra, for his critical review of the manuscript, and J. Cross, for his assistance in metallographic sample preparation and microhardness measurements. It is a pleasure to acknowledge stimulating discussions with P. Krajewski and M. Verbrugge. The work at Brown University was supported by GM through the GM Collaborative Research Lab at Brown University.

A model is developed to allow converting dilatometric strains that occur during the continuous cooling transformation (CCT) of austenite to martensite to volume fraction martensite formed in powder metallurgy steels. Unlike existing models, this model can accurately account for the observed decrease in the measured transformation strain with increased porosity. As a demonstration, the model is used to accurately calculate the volume fraction of martensite formed during the CCT of austenite to martensite in FL-4605 PM steel.

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