Solidification microstructure and high temperature structural stability of laser deposited ultrahigh strength steel AerMet100

The thick plate sample of ultrahigh strength steel AerMet100 was fabricated by the laser melting deposition (LMD). Microstructure of the laser deposited steel was studied by optical microscopy (OM) , scanning electron microscopy ( SEM ) and energy dispersive X-ray spectroscopy ( EDS ) , and high temperature structural stability of which was researched by high temperature solution treatment during 885-1150°C. The results indicate that the rapidly solidified cellular-dendrite structure of the laser deposited steel is fine and homogeneous, and grows directionally along the deposition orientation. Solidification segregation of alloy elements exists between the dendrites and the interdendritic regions, and interlayer heat-affected zone exists between adjacent layers of the laser deposited steel. The rapidly solidified structure has excellent high temperature stability, which was mainly attributed to the low interfacial energy of the dendrite and the slight solidification segregation of alloy element between the dendrites and the interdenrtic regions.