SF 340B Captain reported cracks in a propeller blade on a post flight/pre-flight inspection. The flight crew made a log book entry and communicated with Dispatch and Maintenance.

Narrative

Block out this morning in ZZZ1 was at XA30 UTC. First Officer took the role of pilot monitoring; Captain took the role of pilot flying (PF). PM determined with the help of the Company website that it would be appropriate to set the takeoff to 100% (the temperature used for this calculation was 19 degrees C.). Due to it being the first flight of the day and within temperature limits PM/PF determined takeoff would be conducted with Environmental Control System (ECS) on. Flight crew taxied to Runway XXL and was cleared for takeoff with a 120 initial heading. PM noted aloud to PF during the climbout; that the Interstage Turbine Temperatures (ITTs) reached 910 which is below the 927 limit for takeoff and 917 limit for five minutes. Flight crew continued the flight as cleared by ATC direct ZZZZZ/ZZZ2 then direct ZZZ. During the cruise phase of flight at FL220/FL230 the flight crew did not encounter any icing conditions or require the propeller heat to be turned on at any time. Flight crew agreed ILS to Runway YY would be the most appropriate approach to landing during the descent briefing. Aircraft X taxied; shut down and successfully unloaded freight. During the post flight/preflight for the part 91 leg back to ZZZ3 two large cracks in the propeller blade; near the propeller hub/spinner; on the number two engine side were noted by PF. PF/PM decided to discontinue the flight and notify Maintenance as it appeared the aircraft was in a non-airworthy condition. At no time during engine start; taxi; cruise; landing; taxi; or shut down did anything significant occur. Unknown at this time; as nothing unusual occurred; the flight from ZZZ1-ZZZ was conducted to FAA and Company SOP standards. The flight crew's initial reaction was that the aircraft was not in an airworthy condition. Flight was discontinued; Maintenance and Company were notified of the aircraft's condition.