Microstructural Investigation of M2 High Speed Steel Produced by Selective Laser Melting: Microstructural Investigation of M2 High Speed Steel

Abstract

In SLM, a high energy density is applied by a laser to locally melt layers of metallic powder particles in order to create functional parts. This high energy intensity and additive process character create a specific/unique microstructure. The solidified melt pools in HSS M2 SLM parts are observed to consist of two distinct zones next to the heat affected zone. The first zone, at the bottom of the melt pool, consists of very fine cells and columnar dendrites and has a hardness of 655±80Hv0.1. The other zone contains acicular martensite and has a hardness of 859±80Hv0.1 which is already similar to the hardness of conventionally produced and heat treated HSS M2. Furthermore, the relative amount of these two zones is observed to be dependent on the scan velocity of the laser and hence can be controlled during the SLM process.

Additive manufacturing of high tensile strength steel for offshore & marine 3D complex joint applications

“…The micrographs also showed the possible formation of acicular martensitic structure in the SLM built parts, concurring with the results and observation from the XRD analysis. This is consistent with other reported works for steels built using SLM process [146,147]. This means that the parts produced may exhibit properties similar to martensitic steel, which means high strength and hardness, but relatively low on the toughness values.…”

Corrosion Behavior of the S136 Mold Steel Fabricated by Selective Laser Melting

“…Besides, it can be seen that the bases of the peaks in SLM part are comparatively wider than that in casting. This suggests that the crystal lattice structures of SLM part are experiencing certain level of internal stresses that are thermally induced during the rapid solidification SLM process [29,30]. Moreover, it can be found that the α-Fe diffraction peak of as-SLM S136 slightly moved left compared with that of casting, as depicted in Figure 3(b).…”

Microstructure, Properties and Crack Suppression Mechanism of High-speed Steel Fabricated by Selective Laser Melting at Different Process Parameters

“…Moreover, the coupled mechanism among the laser power, scan speed, scan distance, and substrate temperature was studied in-depth. According to previous studies [18], the high density parts were produced with a scan speed of above 700 mm/s to achieve a uniform microstructure and hardness. Therefore, more than 700 mm/s scan speeds were selected to explore the best parameters.…”