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Abstract The heterogeneity of microstructures in heat affect zone of 9Cr-1.5 W heat resistant steel friction stir welding joint was studied, and its influence on the weld creep property was discussed. The inter critical heat affect zone at the advancing side of the weld is found as the most likely area to be failure during creep, owing to the formation of ferrite grains and lath martensite with low carbon content and the coarsening of M 23 C 6 carbides. The as-welded joint exhibits a good creep resistance of 1173.8 h creep rupture time at 600 °C temperature and 200 MPa stress. Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]

In this work, 316L/CuCrZr functionally graded materials were prepared by laser powder bed fusion. Not only the strong bonding of 316L and CuCrZr was achieved, but more importantly, the grain-size gradients and heterogeneous microstructures were introduced into the samples. The gradient microstructure was characterized by ultrafine equiaxed grains sandwiched between micron-scale columnar grains. The dual-scale heterogeneous microstructure was composed of the BCC α-Fe and FCC ε-Cu phases. This grain size gradient and heterogeneous microstructure ensure that the samples possess high shear and tensile strength. The formation mechanisms of the grain-size gradients and heterogeneous microstructures of the samples were further discussed. The proposed strategy that functionally graded materials with grain size gradients and heterostructures can be fabricated by additive manufacturing may open up a new avenue for materials design. [Display omitted] [ABSTRACT FROM AUTHOR]