Thermographic analysis of the building height impact on the properties of tool steel in selective laser beam melting

Additive manufacturing is becoming increasingly important, as evidenced by the increasing number of media reports and scientific publications. Due to the possibility of producing directly usable components with properties comparable to cast parts, the process is suitable for the production of prototypes and serial components. Quality control is an essential element in the production of serial components and will become an important factor in selective laser beam melting. The study at hand deals with the integration of a thermographic process monitoring, the temperature distribution along the height and its influence on the component properties. For this purpose, the material H13 was choosen by a preheating temperature>550 degrees C. With the infrared camera, a temperature drop of approximately 170 degrees C along the height was observed, which mainly affected the hardness and microstructure. The achieved hardness values were between 614 HV 10 and 662 HV 10. Investigations on the microstructure have shown that a longer period of time at higher temperatures in the lower component area favours the formation of martensitic structures. An influence on the surface roughness, which was almost constant along the height, could not be determined. Roughnesses between R-a=1.5m and R-a = 2.1m were achieved.