Thermal expansion investigations of AISI 4140 steel manufacturing via L-PBF process

Abstract Thermal expansion of AISI 4140 (42CrMo4) steel was characterized from RT to 1100 °C using a NETZSCH DIL 402C dilatometer. The test set comprised two L-PBF specimens—built in-plane (IP) and out-of-plane (OOP) relative to the platform—and a conventionally produced wrought reference (W) from a hot-rolled bar. The measurements reveal a ferrite–austenite transformation accompanied by shrinkage, with characteristic temperatures of 760.5 °C (W), 761.8 °C (OOP), and 758.7 °C (IP). The resulting, wide-range thermal-expansion data provide parameters suitable for numerical heat-transfer simulations in mechanical components fabricated via L-PBF.