Freeform Laser Consolidated H13 and CPM 9V Tool Steels

Abstract

As a novel computer-aided materials additive manufacturing process, the freeform laser consolidation (LC) can directly produce functional shapes (features or structures) through a ''layer-upon-layer'' deposition. In this research, LC processability of both H13 and CPM 9V tool steels and their mechanical performance thus obtained were investigated. Both laser-consolidated tool steels were metallurgically sound with no crack, exhibiting layer-wise refined solidified structures with dominated martensite and small amount of retained austenite, as well as compositiondependent carbides. Laser-consolidated H13 could outperform its wrought counterpart mechanically as measured by tensile strength/strain, and bonding strength as well as sliding wear resistance; laser-consolidated CPM 9V could provide excellent sliding wear resistance superior to the conventional widely used tool steel (such as wrought D2). These unique microstructures and mechanical properties could be tailored for niche applications in additive manufacturing of tools, molds, and dies.

Micro-Texture Analyses of a Cold-Work Tool Steel for Additive Manufacturing

“…For metallic materials, it is generally implemented by selective melting of powder with laser or electron beams [3][4][5][6][7][8][9][10]. Many kinds of metallic powder have been tested for application in mechanical or functional parts [3,[6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] and a few new alloys dedicated to AM are being developed [14,21,22].…”

“…As they constitute the major part of the current engineering metals, steels can make a great contribution to the spread of AM applications. Among various steels, tool steels are well suited to AM [17][18][19][20][21][22][23], and become parts of the representative commercial steel powder for AM [23]. They generally have high alloy contents and suffer from excessive heterogeneities owing to segregation when they are provided via the conventional ingot metallurgy route [24].…”

“…They generally have high alloy contents and suffer from excessive heterogeneities owing to segregation when they are provided via the conventional ingot metallurgy route [24]. Thus, the fine and homogeneous microstructures produced by selective melting of powder [17][18][19][20][21][22] should be much more attractive. Machinability of the conventional wrought or cast tool steels is an important requirement by toolers [24], and the near-net-shape by AM should be another attraction to these difficult-to-machine materials.…”

“…In spite of the aforementioned advantages, only a limited number of documents are still found on the AM applications of tool steels [17][18][19][20][21][22], while most of them dealt with standard hot-work or plastic tool steels such as AISI H13 and P20 [17][18][19][20]. It would be harder to find ones that dealt with more highly alloyed cold-work tool steels [21,22].…”

“…It would be harder to find ones that dealt with more highly alloyed cold-work tool steels [21,22]. Although those works reported some results of microscopic observations [17][18][19][20][21][22], more detailed and quantitative information on the morphologic and the crystallographic characteristics of the microstructures would improve the current knowledge for the AM of tool steels.…”