Die steel material suitable for selective laser melting in-situ heat treatment and preparation method thereof

The invention belongs to the field of selective laser melting in-situ aging strengthening materials, and particularly relates to a die steel material suitable for selective laser melting in-situ heat treatment, the die steel material comprises FeNiCoMoTi, and the die steel material comprises the following element components in percentage by mass: 14-16% of Ni, 7-9% of Co, 6-8% of Mo, 2-8% of Ti, less than or equal to 0.077% of Al, less than or equal to 0.09% of Si, less than or equal to 0.007% of C and the balance of Fe. According to the method, in-situ aging strengthening is taken as a starting point, and on the basis of selective laser melting in-situ aging strengthening, a second-phase nano precipitate is rapidly separated out in a short process of in-situ aging strengthening, and a favorable nucleation position is provided for a precipitated phase which is slowly separated out subsequently; and a pinning effect is generated through high-density dislocation movement in a martensite matrix, and second-phase