Thermal conductivity of tool steel made with additive manufacturing technology

Orodno jeklo za delo v vročem H13 je visokokakovostno in v inženirski praksi pogosto uporabljeno jeklo. V diplomskem delu smo obravnavali njegovo različico izdelano z aditivno tehnologijo t.i. 3D tiska kovinskih materialov. V okviru eksperimentalnega dela smo izvedli meritve toplotne prevodnosti in specifične toplote ter določili temperaturno prevodnost pri sobni temperaturi jekla izdelanega z aditivno tehnologijo in jih primerjali z vrednostmi za jeklo izdelano po klasični proceduri. Meritve, vrednotenje in analizo smo izvedli na napravi za določanje toplotnih lastnosti Hot Disk TPS 2200 v skladu s standardom ISO 22007-2. Vrednosti toplotnih lastnosti jekla H13 izdelanega po klasični metodi znašajo: toplotna prevodnost 26,81 W?m-1?K-1, specifična toplota 3,73 MJ?m-3?K-1 in temperaturna prevodnost 7,19 mm2?s-1. Vrednosti toplotnih lastnosti jekla za delo v vročem H13 izdelanega s 3D tiskom pa so: Prvi poizkus: toplotna prevodnost 18,16 W?m-1?K-1, specifična toplota 3,57 MJ?m-3?K-1 in temperaturna prevodnost 5,09 mm2?s-1, Drugi poizkus: toplotna prevodnost 18,60 W?m-1?K-1, specifična toplota 3,64 MJ?m-3?K-1 in temperaturna prevodnost 5,11 mm2?s-1. Ugotovili smo, da so toplotne lastnosti jekla H13 izdelanega z 3D tiskom manjše od jekla H13 izdelano po klasični metodi: toplotna prevodnost manjša za 8,21 W?m-1?K-1, specifična toplota manjša za 0,09 MJ?m-3?K-1in temperaturna prevodnost manjša za 2,08 mm2?s-1. Sklepamo, da je glavni razlog prisotnost zračnih mehurčkov oziroma por v vzorcu.Hot tool steel H13 is a high-quality and widely used steel in engineering practice. In the thesis, we discussed its version made with additive technology, the so-called 3D printing of metal materials. As part of the experimental work, we performed measurements of thermal conductivity and specific heat and determined the temperature diffusivity at room temperature of steel produced with additive technology and compared them with the values for steel produced according to the classical procedure. Measurements, evaluation and analysis were performed on the Hot Disk TPS 2200 device for determining thermal properties in accordance with the ISO 22007-2 standard. The values of the thermal properties of H13 steel produced by the classic method are: thermal conductivity 26.81 W⠙m-1⠙K-1, specific heat 3.73 MJ⠙m-3⠙K-1 and temperature diffusivity 7.19 mm2⠙s-1. The values of the thermal properties of the H13 hot work steel produced with 3D printing are: First test: thermal conductivity 18.16 W⠙m-1⠙K-1, specific heat 3.57 MJ⠙m-3⠙K-1and temperature diffusivity 5.09 mm2⠙s-1, Second test: thermal conductivity 18.60 W⠙m-1⠙K-1, specific heat 3.64 MJ⠙m-3⠙K-1 and temperature diffusivity 5.11 mm2⠙s-1. We found that the thermal properties of H13 steel produced by 3D printing are lower than H13 steel produced by the classical method: thermal conductivity lower by 8.21 W⠙m-1⠙K-1, specific heat lower by 0.09 MJ⠙m-3⠙K-1 and temperature diffusivity smaller by 2.08 mm2⠙s-1. We conclude that the main reason is the presence of air bubbles or pores in the sample