High Speed Steel Parts Research Articles

Direct ink writing of metal parts with curing by UV light irradiation

To develop a low-cost 3D printing technology for metal parts, we combined the direct ink writing technology with UV light curing to print complex-shaped high-speed steel parts. To obtain the printing slurry, metal powders were mixed with photosensitive resin. After optimizing the printing slurry and printing parameters, the photosensitive resin formed a robust cross-linking network under UV light irradiation, thus bonding powder particles together. The printed sample had good printing quality without any pores or defects found. The surface roughness was about 1.58 μm. After sintering, the as-sintered sample had homogeneous microstructure, relatively high density of 98.2 %, and low surface roughness value of 0.42 μm. Uniform sintering shrinkage with a shrinkage coefficient of 9% was observed. Overall, one promising technology was proposed to print metal parts with complex shapes by UV-assisted direct ink writing.

Complex-shaped high speed steel with high mechanical performance fabricated by gelcasting sintering

Abstract Hot isostatic pressing is the most common method to prepare powder metallurgy high speed steel. However, due to the limitation of the steel capsule, it is still a challenge to directly produce complex-shaped high speed steel. Therefore, a gelcasting sintering process is proposed in this study. Complex-shaped high speed steel parts were prepared. First, fine powders (10 μm) were employed to prepare a gelcasting slurry. Then, the slurry was poured into a silicone mould followed by debonding and pressureless sintering. Nearly full densification was achieved in the gelcasting sintered samples. Homogeneous microstructure was observed with fine carbides (1 – 2 μm) evenly distributed in the matrix. Compared to traditional samples prepared by hot isostatic pressing, the bend strength increased from 2 800 MPa to 3 800 MPa. Additionally, the oxygen content of the sintered samples was lower than 100 ppm.

Characteristic properties of AlTiN and TiN coated HSS materials

Purpose – The purpose of this paper is to examine mechanical and metallurgical properties of AlTiN- and TiN-coates high-speed steel (HSS) materials in detail. Design/methodology/approach – In this study, HSS steel parts have been processed through machining and have been coated with AlTiN and TiN on physical vapour deposition workbench at approximately 6,500°C for 4 hours. Tensile strength, fatigue strength, hardness tests for AlTiN- and TiN-coated HSS samples have been performed; moreover, energy dispersive X-ray spectroscopy and X-ray diffraction analysis and microstructure analysis have been made by scanning electron microscopy. The obtained results have been compared with uncoated HSS components. Findings – It was found that tensile strength of TiAlN- and TiN-coated HSS parts is higher than that of uncoated HSS parts. Highest tensile strength has been obtained from TiN-coated HSS parts. Number of cycles for failure of TiAlN- and TiN-coated HSS parts is higher than that for HSS parts. Particularly TiN-coated HSS parts have the most valuable fatigue results. However, surface roughness of fatigue samples may cause notch effect. For this reason, surface roughness of coated HSS parts is compared with that of uncoated ones. While the average surface roughness (Ra) of the uncoated samples was in the range of 0.40 μm, that of the AlTiN- and TiN-coated samples was in the range of 0.60 and 0.80 μm, respectively. Research limitations/implications – It would be interesting to search different coatings for cutting tools. It could be the good idea for future work to concentrate on wear properties of tool materials. Practical implications – The detailed mechanical and metallurgical results can be used to assess the AlTiN and TiN coating applications in HSS materials. Originality/value – This paper provides information on mechanical and metallurgical behaviour of AlTiN- and TiN-coated HSS materials and offers practical help for researchers and scientists working in the coating area.

Selective Laser Melting of Crack-Free High Density M2 High Speed Steel Parts by Baseplate Preheating

Cracks and delamination, resulting from residual stresses, are a barrier in the world of additive manufacturing and selective laser melting (SLM) that prohibits the use of many metals in this field. By preheating the baseplate, thermal gradients are lowered and stresses can be reduced. In this work, some initial tests were performed with M2 high speed steel (HSS). The influence of preheating on density and mechanical and physical properties is investigated. The paper shows many promising results for the production of SLM parts in materials that are very sensitive to crack formation and delamination. When using a preheating of 200 °C, crack-free M2 HSS parts were produced with a relative density of 99.8%.

Effect of Heat Treatment Process of Sintered M3/2 High Speed Steel Parts

Dry machining is one of the ways to achieve a reduction of cooling lubricants, as well as reduced environmental pollution and lower health risk to workers. This leads to higher mechanical and thermal loading on cutting edges. The adaptation of cutting tools to the requirements of dry machining includes the optimisation of manufacturing technologies, the development of cutting materials of sufficient toughness and high hot hardness, the design of tool geometries as well as the coating of tools [.

Crystal structure analysis of M2 high speed steel parts produced by selective laser melting

M2 high speed steel (HSS) samples were produced by an additive manufacturing (AM) process, selective laser melting (SLM). The observed microstructure from SEM and FIB was characterised by a continuous and homogeneous network of dendrites within two different phases. These phases were characterised to be bcc single crystals and fcc/bcc polycrystals from TEM-SADP. EBSD results also indicated that the bcc grains were randomly orientated. In addition, the lattice constants from two different SADPs of bcc crystal were calculated to be 2.892Å and 2.905Å, larger than high purity iron bcc structure of lattice constant 2.867Å. The elements V, Cr, Mo, W and Si were detected in the iron matrix with TEM-EDS. These elements were responsible for the enlargement of the lattice constant. TEM-EDS results also indicated that the network of dendrites were carbides. These results gave insights on the rapid solidification phenomenon in SLM.

Effect of Residual Carbon on the Microstructure Evolution during the Sintering of M2 HSS Parts Shaping by Metal Injection Moulding Process

In this present investigation, Metal Injection Moulding (MIM) of M2 High Speed Steel (HSS) parts using a wax-High Density Polyethylene (HDPE) binder is shown. This work is focused on the examination of the sintering densification and microstructure evolution of the parts. The injection molding process of the feedstock has been optimized to obtain high quality green parts. The elimination of organic binder was carried out by thermal debinding under inert atmosphere. In order to keep carbon in the sample that could improve the sintering process, incomplete debinding was performed between 450 and 600 °C. The specimens were sintered at temperatures between 1210 and 1280oC in high vacuum atmosphere, obtaining the 98% of the theoretical density. A homogeneous distribution of fine M6C carbides was obtained as well as V-rich carbides (MX) during sintering which reinforced the HSS and hence increasing the mechanical properties of the parts. In the samples with higher residual carbon content, the sintering window was extended up to 20 degrees and the optimum temperature was lower.

Low-Pressure Injection Molding Processing of AISI T15 High Speed Steel Powders

Low-pressure powder injection molding was used to obtain AISI T15 high speed steel parts. The binders used were based on paraffin wax, low density polyethylene and stearic acid. The metals powders were characterized in terms of morphology, particle size distribution. The mixture was injected in the shape of square bar specimens to evaluate the performance of the injection in the green state, and then sintered. The samples were injected under the pressures of 0.4, 0.5 and 0.7MPa and at temperatures varying from 110 to 150°C aiming the optimization of the process. The results of the variation of injection pressure were evaluated by measuring the density of the green parts. Debinding was carried out in two steps: first, the molded part was immersed in heptane to remove the major component of the binder and then heated to remove the remaining binder. A second step debinding and sintering were performed in a single step. This procedure shortened considerably the debinding and sintering time.

The influence of MoS 2 additions on the densification of water-atomized HSS powders

Molybdenum disulphide (MoS 2) might be a useful addition in the production of composite self-lubricating high-speed steel parts, which are used in different anti-wear applications. MoS 2 might also has a favourable influence on the synthesis of sintered high-speed steels (HSSs) improving the compressibility of the metal powder mixture during its cold compaction, as well as acting as a sinterability enhancer of powder compacts during their sintering. In view of this, the compressibility and the sinterability of M3/2 and M35 types of HSS powder mixtures with MoS 2 additions were investigated. In this article, the influence of MoS 2 additions on the densification during cold compaction and vacuum sintering of selected HSSs is presented. It has been established that the MoS 2 promotes a consolidation of HSS powders during automatic die compaction, as well as final densification during sintering. Sintering of HSS-MoS 2 powder mixtures proceeds by the combination of a reactive and supersolidus liquid-phase sintering process. The added MoS 2 reacts with the steel matrix, enhancing densification. Fine dispersion of complex sulfides (Cr, V, Fe)S is formed, which improves the machinability and tribological properties of sintered steel.

Metal injection moulding of HS12-1-5-5 high-speed steel using a PW-HDPE based binder

In this communication, we present the powder injection moulding (PIM) of HS12-1-5-5 high-speed steel parts using a wax-HDPE based binder. The injection moulding process of the feedstock (68 vol.% of metal) has been optimized to obtain high quality green parts. The elimination of organic binder was carried out by thermal debinding under inert atmosphere. In order to keep carbon in the sample that could improve the sintering process, incomplete debinding were performed between 450 and 500 °C. In this study, we have studied the effect of different atmospheres on the debinding process. Debinding was performed under nitrogen and argon. The specimens were sintered at temperatures between 1200 and 1300 °C with steps of 10 °C in following mixture N 2–10% H 2 atmosphere. The PIM parts present higher density than those obtained by conventional PM.

Processing conditions and mechanical properties of high-speed steel parts fabricated using direct selective laser sintering

This paper reports the results of an investigation into the selective laser sintering of a prealloyed high-speed steel powder. The structured development of processing conditions for single lines, single layers and multiple layers of material is reported, as are the flexural modulus and strength of the single- and multiple layer components. Infiltration with bronze was used to improve the mechanical properties of the components and it is concluded that selective laser sintering of high-speed steel allied to bronze infiltration can produce material with the mechanical properties to allow for use in load-bearing applications, but that further work is required to improve the density, mechanical properties and build rate if selective laser sintering is to develop as a general manufacturing process for hard metals.

Effect of residual carbon on the sintering process of M2 high speed steel parts obtained by a modified metal injection molding process

In this article, we present the evolution of the microstructure during sintering of M2 high speed steel (HSS) parts obtained by a modified powder injection molding (PIM) process, which uses a new binder system based on a thermosetting resin. The most important characteristics of this process is that molding is carried out at room temperature by pouring the slurry (resin and tool steel previously mixed) directly into the mold. The mold is then heated to the curing temperature of the resin. The best mixture of polymer and steel powders was 60 pct volume of metal powder. The resin was removed by thermal debinding. The sintering process was carried out under vacuum atmosphere. We tested different debinding temperatures in order to retain residual carbon in the samples coming from the thermal degradation of the polymer. The best results were obtained at low debinding temperature (300 °C). In this case, residual carbon had a beneficial effect, extending the sintering temperature range by 100 deg, making it possible to reach very high density at temperatures as low as 1100 °C. The mechanism of this densification seems to be via supersolidus liquid phase (SPLS). The microstructural study of sintered parts revealed a homogeneous distribution of carbides that change their morphology with increasing temperature. Besides spherical M6C carbides, which appear in all the temperature ranges studied, a new rodlike M2C carbide appears.

Vacuum sintering of water-atomised HSS powders with MoS 2 additions

Molybdenum disulphide (MoS 2) is a well-known and widely used solid lubricant. As such, it might also be a useful addition in the production of composite self-lubricating high-speed steel parts which are used in different anti-wear applications. MoS 2 might also have a favourable influence on the synthesis of sintered HSS. In view of this, the compressibility and the sinterability of M3/2 and M35 types of HSS powder mixtures with MoS 2 additions were investigated. In this paper, the influence of MoS 2 on the densification during vacuum sintering of selected HSSs is presented. It has been established that the densification of HSS-MoS 2 powder mixture proceeds by a combination of a reactive and super-solidus liquid-phase sintering process. The added MoS 2 reacts with the steel matrix, enhancing densification. Complex sulphides (Cr, V, Fe)S are formed, whilst the Mo enriches the steel matrix and forms complex carbides with other alloying elements.

Effect of powder type on properties of injection moulded high speed steel parts: H. Miura, T. Honda (Kumamoto University, Kumamoto, Japan)

Effect of powder type on properties of injection moulded high speed steel parts: H. Miura, T. Honda (Kumamoto University, Kumamoto, Japan)

Synthesis and magnetic properties of ferrite-metal composite powders : N.Hiratsuka et al (Saitama University, Urawa, Japan) J.Japan Soc. Powder and Powder Metallurgy, vol 40, no 10, 1993, 998–1001. (In Japanese)

Molybdenum disulphide (MoS2) is a well-known and widely used solid lubricant. As such, it might also be a useful addition in the production of composite self-lubricating high-speed steel parts which are used in different anti-wear applications. MoS2 might also have a favourable influence on the synthesis of sintered HSS. In view of this, the compressibility and the sinterability of M3/2 and M35 types of HSS powder mixtures with MoS2 additions were investigated. In this paper, the influence of MoS2 on the densification during vacuum sintering of selected HSSs is presented. It has been established that the densification of HSS-MoS2 powder mixture proceeds by a combination of a reactive and super-solidus liquid-phase sintering process. The added MoS2 reacts with the steel matrix, enhancing densification. Complex sulphides (Cr, V, Fe)S are formed, whilst the Mo enriches the steel matrix and forms complex carbides with other alloying elements.

Use of repetitive compaction for production of high speed steel parts: H. Tsuru and T. Nakagawa (University of Tokyo, Tokyo, Japan), J Japan Soc Powder and Powder Metallurgy, Vol 40, No 1, 1993, 8–11. (In Japanese).

Use of repetitive compaction for production of high speed steel parts: H. Tsuru and T. Nakagawa (University of Tokyo, Tokyo, Japan), J Japan Soc Powder and Powder Metallurgy, Vol 40, No 1, 1993, 8–11. (In Japanese).

電動式ＣＮＣ粉末成形プレスを利用した継ぎ足し成形法による粉末高速度鋼部品の製造 圧縮軸方向密度分布への影響

Water-atomized high speed steel powder was pressed into a component with high aspect ratio by repetitive compaction process using electric drive CNC press and the uniformity of green density along the compacting axis was investigated. For the dimensional accuracy the uniform density distribution is very important because of large linear shrinkage ratio of about 10% during vacuum sintering. The CNC compacting press has superior versatility of compaction sequences and makes it possible to minimize the difference of local green density by repetitive compaction which consists of several sets of powder filling and compaction.The green compact(φ14×45) by repetitive compaction showed fairly uniform density distribution and smaller local density variation compared with green compact by conventional single compaction. The measured profile curves along a side wall of sintered parts were in good agreement with the predicted density distribution and the dimensional variation in radial direction was reduced. Tensile strength was equivalent to that of conventional part and the breakage didn't occur at the joining point. The experimental results shows the possibility of near-net-shape production of P/M high speed steel parts with large height.

Production and Heat Treatment of Fully Dense Pressed and Sintered PM Tool Steels

The key steps of a PM technique for manufacturing fully dense near net shape tool steel parts are described. The main production steps are powder preparation, compaction, and sintering. The pre- alloyed powders used in the process are annealed to soften them, making compacting to fairly high green densities possible. Sintering to full density is accomplished at a closely controlled temperature near the solidus of the material. The heat treatment response of sintered high-speed steel parts is similar to that of conventionally produced steels. A model for the calculation of the necessary carbon content to achieve full hardness during the heat treatment of high-speed steels was developed. The model is based on predicting the amount and approximate chemical composition of the carbides present after quenching from the austenitizing temperature and the subsequent calculation of the carbon tied up within the carbides. PM/0207