In order to develop the technology of rapidly precision spray forming tooling

microstructure and mechanical properties of HM1 hot forging die processed by precision spray forming were investigated by OM （optical microscope）

SEM（scanning electron microscope）

XRD （X-ray diffraction） and mechanical testing

and were compared with those of one processed by conventional casting tooling. The results indicate that the HM1 hot forging die with good surface quality and clear outline can be produced

and the average relative density reaches 99.5%. The grain size in spraying formed tool is approximately 15 μm

compared with about 100 μm in casting tool

significantly refined. After tempering at 520 ℃ for 2 hours

the hardness of the spraying formed specimen is HRC54

while it is only HRC49 in the casting specimen. The fracture analysis shows that the casting specimen exhibits the mixture fracture with brittle fracture and ductile fracture

and the typical ductile fracture is presented in the spray formed specimen.