Effect of additive and subtractive hybrid manufacturing process on the surface quality of 18Ni300 maraging steel

Abstract

The effect of process parameters on the surface quality of 18Ni300 maraging steel formed by selective laser melting (SLM) was investigated. The surface modification of SLM specimens was carried out using milling as a subtraction method to study the effect of milling process parameters on the surface quality of SLM specimens processed by milling. Comparing and analyzing the surface quality after additive and subtractive, the results of the study show that the increase of laser power during SLM can improve the surface morphology, but there is always a balling effect. The surface quality gets worse when the scanning speed increases. When the laser power increases or the scanning speed decreases, the microhardness increases and the error decreases. The residual stress does not vary linearly with the change of laser power or scanning speed, and the scanning speed has a greater effect on the residual stress than the laser power. The best surface quality is achieved at a laser power of 180 W and a scanning speed of 300 mm/s. Laser power and scanning speed had no significant effect on the microstructure of SLM-formed specimens. In the milling process, an increase in the feed rate will make the surface quality worse, and an increase in the cutting speed will make the surface quality better. The surface quality was best when the cutting speed was 10m/min and the feed rate was 36mm/min. The grain refinement effect is weakened when the feed rate is increased, and the grain refinement effect is enhanced when the cutting speed is increased. The surface quality of SLM-formed maraging steel specimens improved to some extent after milling.

Study on overlap rate and machinability of selected laser melting of maraging steel

“…The surface roughness of Figure 13b was measured to be 0.342 µm. The improved surface quality after milling is convenient for subsequent use [43].…”

“…The most intensive abrasion occurs in the process of band extrusion, where the production mass is mixed, homogenized, vented, and formed [7]. This process is currently realized in horizontal band plungers, which are made up of a two-shaft mixer and a pug mill [8,9]. The production mass processed by these machines is at a humidity level of 20%-25% and is compressed in the pug mill head under 2-10 MPa of pressure.…”

“…The material properties of maraging steels are well suited to the laser powder bed fusion process to produce parts that require excellent strength, hardness, and thermal stability, making 18Ni300 * E-mail: 1552613466@qq.com maraging steel suitable for additive manufacturing [8]. Using different directions and methods, a large number of scholars have also carried out research on 18Ni300: Sung et al [9] used selective laser melting (SLM) to prepare volume cubic 18Ni300 maraging steel and studied the relationship between macro-and micro-mechanical properties and process parameters.…”

The Effect of Selective Laser Melting Fabrication Parameters on the Tensile Strength of an Aged New Maraging Steel Alloy with 8% Cr, Reduced Ni Content (7%), and No Co or Mo

“…As a consequence of this heating, residual stresses appear in the material due to the large thermal gradients involved [41][42][43][44]. The factor most likely to cause defects in the interlayer bond is balling [45][46][47][48]. If balling occurs in a previously solidified layer, thus making the surface of this layer irregular and corrugated, it will lead to a significant variation in the thickness of the next deposited powder layer [40,49].…”

“…To eliminate the bond defect and form a solid bond between two consecutive layers, a stable melt pool created under optimised fabrication parameters is essential, as this promotes sufficient partial remelting of the previous layer [40]. The main fabrication parameters of the process used to produce LeanSi are laser power (LP), layer thickness (LT), scanning speed (SS), and hatch distance (HD) [46]. These fabrication parameters allow the process to be characterised in terms of energy density [3,4,12,40,45,50].…”