M2 Powder Research Articles

Microstructure and mechanical properties of high carbon M2 powder metallurgy high-speed steel prepared by the carbide addition

ABSTRACT This paper used carbonyl iron powder and carbide powder as raw materials to prepare high carbon M2 powder metallurgy high-speed steel through the cold compaction-sintering method. The evolution of microstructure and properties of the material at different sintering temperatures were emphatically studied. The results show that: The microstructure of the samples is that different types of carbides are uniformly dispersed in the matrix. Since the dissolution of the original carbides is a continuous process, the precipitated carbides are constantly changing with the increase of sintering temperature. Moreover, M2 steel achieves sintering densification near the solidus temperature, the sintering window is expanded to 10–15°C. In the sintering temperature range, the carbides in the samples are fine and uniformly dispersed. The material sintered at 1225°C has the best mechanical properties, with a bending strength of 2754 MPa, and a hardness of 51 HRC. In addition, mechanical properties are greatly improved by heat treatment.

Effect of P21 buffer layer on interfacial bonding characteristics of high‑carbon tool steel hardfaced through directed energy deposition

The elevated hardness of high‑carbon tool steel (M2) powder makes it an effective material for hardfacing components requiring strong wear resistance. However, if the brittle M2 powder is deposited on a ductile substrate, significant stress occurs during cooling, leading to defects, such as cracks at the interface between the substrate and deposited regions. Therefore, in this study, ductile P21 powder was deposited as a buffer layer between the substrate and the deposited M2 layer to prevent interface defects. To confirm whether this P21 buffer layer effectively prevents interfacial defects, bending, impact, and tensile tests were performed. No interfacial defects were observed in the cross-section of the deposition specimen when a P21 buffer layer was applied. The average hardness of the surface deposited M2 region was 733 HV, similar to that of the carburized substrate. As-built (M2) specimen showed 94% lower in weight reduction than the carburized material after the wear test. The specimen without a buffer layer revealed cracks propagating along the interface between the deposited region and substrate, with the lowest impact energy absorption of 25 J. However, the energy absorption of the specimen with a P21 buffer layer was 60% higher than that without a buffer layer. The tensile test results show 7% increase in tensile strength with the buffer layer and 244% increase in elongation. This study demonstrated that high hardness and wear resistance could be achieved through M2 deposition and confirmed the improved strength and toughness with a P21 buffer layer.

Thermal fatigue life and improvement mechanism of Fe-based coatings on H13 extrusion die by laser additive remanufacturing

H13 extrusion dies are often damaged by wear, erosion and thermal fatigue, and laser additive remanufacturing is an effective method to repair damaged locations to extend their service lives of H13 steel dies. In this study, Fe-based coatings are fabricated on the surface of H13 extrusion punches by laser cladding using the Fe-based powder mixed with M2 powder of different contents, and the effects of the M2 powder on the phase compositions, tensile properties, wear performance and thermal fatigue life are systematically investigated. Results indicate that the refined structures and various types of carbides are contained in all Fe-based coatings after adding M2 powder. Compared with other three coatings, the Fe-based coating mixed with 15 wt% M2 powder exhibits better thermal fatigue life. As a consequence, an influence mechanism of M2 powder on microstructural evolution and mechanical property is also presented in detail.

Oxidation characterization of M2 powders exposed under humid atmosphere for a long time

Atomized M2 powders were stored in an atmosphere of 80% relative humidity for a long time. The oxidation characteristics of atomized alloy powders were analyzed. The results show that the oxygen content of the powders have an increasing trend with the prolongation of storage time under humid atmosphere. The oxygen content of 150-300 mesh coarse powder has a gentle change, and the oxygen content will be reduced to near the original level after drying. The oxygen content of -300 mesh fine powders has a little growth in a short time, but it increases rapidly as time goes on after one week, and increases from 415 ppm to 1098 ppm after four weeks of storage, and the oxygen content of fine powders after drying remained unchanged. Particle size has a great influence on the oxidation characteristics of powders. The smaller the particle size, the greater the oxygen content of the powder. The type of adsorption of oxygen element from coarse powder to fine powder changes from physical adsorption to chemical adsorption.

Effect of powdered laser surfacing modes on structure and properties of wear-resistant coating and new medium carbon steel with yield strength 1500 MPa

This paper studies coatings obtained by laser cladding of M2 powder material (Hoganas, Belgium) on a new B1500 medium-carbon steel. The analysis of defects (pores, cracks), microstructure, phase composition, microhardness of the deposited coatings depending on heat input of laser radiation was performed. The results of tests for wear resistance of coating samples, which allow selecting the optimal modes of laser deposition, are presented.

Contact Interaction Peculiarities at the Boundary of Layers of Structural Steel–High-Speed Steel Hot-Forged Powder Bimetal

The main problem in the production of bimetals (BMs) is the necessity to ensure adhesive interaction at the contact boundary of the layers, preventing their delamination during the operation. Hot forging of porous preforms (HFPP) offers the possibility of fabricating high-density powder BMs with a minimal amount of pores both in the bulk of the layer material and at the boundary between the layers, which promotes an increase in the adhesion strength. When fabricating hot-forged powder BMs, it is possible to mix materials of charges of a working layer and a substrate, which can lead to uncontrollable interface “spread.” In this work, to fabricate porous BM performs of the structural steel–high-speed steel type, the previously proposed method foreseeing the preliminary prepressing of the powder of the hard-to-deform material is used. In order to determine mechanical properties and perform a structural analysis, bilayer cylindrical samples 20 mm in diameter and 30 mm in length are prepared. The BM base material is steel PK40 and that of the working layer is atomised high-speed steel M2 powder with satisfactory compressibility characteristics. Porous preforms of BM samples are pressed in a specially designed mold using a hydraulic press, enabling one to perform two-side pressing of bilayer powder moldings with the specified distribution of density and strength of layers. Cold-pressed BM preforms were sintered in a protective atmosphere and then subjected to hot repressing using a laboratory drop hammer. Some preforms are examined as sintered. In addition, hot repressing of cold-pressed green preforms is performed. The satisfactory process strength of the working layer material is observed at its porosity of 34% 45% and delaminates at Pwl < 34%. It is established that the maximal layer bonding strength and BM thermal-shock resistance is provided by the application of a flowsheet foreseeing the preliminary sintering of cold-pressed preforms and subsequent hot forging. The optimal repressing pressure of the working layer is 145 MPa.

Optimizing the Distribution System of Fast Moving Consumer Goods Company Using Sweeping Methods with Discrete Event Simulation Approach

FMCG is considered as one of the industry with the highest competition in the world. To win this industry, customer satisfaction becomes the main thing. In this paper, authors will simulate a system of distribution of goods from PT X TBK which has 3 categories, namely M1 (biscuit), M2 (powder) and M3 (liquid). The distribution system has a problem on time delivery of goods which have a wide variety of obstacles, mainly on routing. There are 8 trucks with different routes and different utilization. There's trucks with over hour work and trucks with long idle time. The routing also causes problem for unused truck weight and volume capacity, where cost could possibly be reduced. Through Discrete event simulation and sweeping method, authors try to solve the problem by modelling the existing system and then find the solution to improve the distribution system and reaching the model objective.

AISI M2 파우더를 이용한 SKD61 재질의 레이저 메탈 디포지션 기초 특성 분석

ABSTRACT In this study, AISI M2 powder was selected primarily through various pieces of literature in order toimprove the hardness and wear resistance. Among the laser metal deposition parameters, laser power wasstudied to improve the deposition efficiency in the laser metal deposition using a diode-pumped disk laser.An SKD61 hot work steel plate and AISI M2 powder were used as a substrate and powder for laser metaldeposition, respectively. Experiments for the laser metal deposition were carried out by changing the laserpower and track layer. The quality of the track surface and cross-section after applying the single-layermethod was better than that obtained from applying the multi-layer method. As the laser power increased, thetrack thickness was increased, and the surface roughness deviation was decreased. In laser power condition of1.6kW, the maximum hardness of the deposition track was 790Hv. This value was 40% better than thehardness of the SKD61 after heat treatment.Key Words : AISI M2 Powder(철계파우더), SKD61(열간금형강), Laser Metal Deposition(레이저메탈디포지션), Track(트랙), Layer(적층)

트랙 이행거리에 따른 SKD61 재질의 레이저 메탈 디포지션 기초 특성 분석

In this study, AISI M2 powder was selected primarily through various literature in order to improve the hardness and wear resistance. Among the laser metal deposition parameters, laser power was studied to improve the deposition efficiency in the laser metal deposition using a diode pumped disk laser. SKD61 hot work steel plate and AISI M2 powder were used as a substrate and powder for laser metal deposition, respectively. Fixed parameters are CTWD, focal position, travel speed, powder feed rate, etc. Experiments for the laser metal deposition were carried out by changing laser power. Through optical micrographs analysis of cross-section in LMD track, effect of the major parameters were predicted by track pitch. As the track pitch increased, so the reheated zone width, the overlap width and the minimum thickness was decreased. The hardness was decreased in the HAZ area, the hardness in the reheated HAZ area was decreased significantly and regularly in particular.

Improvement in wear characteristics of the AISI M2 by laser cladding and melting

The interest of high speed steel (HSS) for wood cutting tools remains very important because of their good tool edge accuracy and easy grinding. The main problem is their low resistance to both mechanical and chemical wearing. Resistance of HSS cutting tools to wearing is a primary concern in the applicability of the HSS cutting tools to a wood cutting operation. In order to increase their performance, a laser melting and cladding applied on the tool edges is presented in this paper. First, the annealed AISI M2 bar was melted, and the M2 powder was cladded onto the AISI L2 substrate by a laser beam. The microstructure and microhardness of the M2-clad and M2-melted were characterized. Second, their wear resistance was tested for cutting wood. The experimental results showed that the microstructures on the clad zone (CZ) of M2-clad and melted zone (MZ) of the M2-melted reveal fine and homogeneous iron dendritic structure, in which whole primary carbides were completely dissolved during laser cladding and melting. The energy dispersive spectroscopy (EDS) analysis indicated that the M2-clad reveals CZ microstructure with more uniform distribution of fine carbides compared to MZ microstructure. The M2-clad and M2-melted, which present almost the same microhardness, have larger microhardness compared to the M2-conventional. The results of wearing tests showed that the M2-clad and M2-melted cutting tools are better in wear resistance, edge roughness, and suffer less edge fractures than the M2-conventional peeling tool. Laser melting and cladding are considered to be valuable techniques to improve the performance of the M2 high speed steel cutting tools for wood machining application.

Performance of laser-treated AISI-M2 cutting tools for peeling beech

For many wood machining processes, the interest of tool steels remains very important because of their good tool edge accuracy and easy grinding. The main problem is their low resistance to wearing and corrosion. In order to increase their performance, a laser melting and cladding applied on the tool edges is presented in this paper. Firstly, annealed AISI-M2 bar was melted, and M2 powder was cladded onto the AISI L2 substrate by a laser beam. The microstructure and microhardness of the M2 melted and M2 clad were characterised. Secondly, their wear resistance was tested for peeling beech wood. The experimental results show that metallurgical structure obtained by conventional heat treatment for the M2 was ferritic polycrystalline with coarse primary carbides, and the microstructure of the M2 melted and M2 clad, in which whole primary carbides were completely dissolved during laser melting and cladding, was observed to reveal fine iron dendritic structure. The M2 melted and M2 clad, which were almost the same in microhardness, had larger microhardness compared to the M2 conventional. The wear resistance and wear pattern of the M2 melted and M2 clad cutting tools in peeling beech were better than those of the M2 conventional cutting tool. Also the M2 melted and M2 clad cutting tools produced better surface quality of veneer and retained better cutting edges roughness compared to the M2 conventional.

Densification of AISI M2 high speed steel by means of capacitor discharge sintering (CDS)

Abstract Ball milled AISI M2 high speed steel (HSS) powders with nanometric crystalline grains have been consolidated by means of a new technique called capacitor discharge sintering (CDS) which employs one single high intensity current pulse (up to 100 MA/mm2in 10–20 ms) and high pressure (up to 400 MPa). The consolidated disks with diameter of 10 mm and 2–3 mm thickness, show low residual porosity and very fine microstructures. It is confirmed that the CDS process is well suited for the complete densification of AISI M2 powders without grain growth.

Processing of M2 powder metallurgy high-speed steel by means of starch consolidation

A study is made of a new method called starch consolidation (SC) for the production of powder metallurgy (P/M) high-speed steel (HSS) components. Samples of a commercial HSS, M2, were shaped by using 1.5, 3.5 and 5 vol% of starch and up to 60 vol% of powder. The high solids loading was made possible by a small addition (0.03 wt%) of dispersant (polyacrylic acid) that stabilized the repulsive forces and provided the desired fluidity to the slurries. After shaping and demoulding, the bending strength of the green bodies was evaluated. Debinding cycles were optimized by comparing the carbon content in argon, in a mixture of N 2–5H 2 and in pure hydrogen atmospheres at 450 and 600 °C. The three atmospheres caused no significant differences in carbon removal. Best results were achieved from sintering in vacuum with a debinding cycle in H 2 up to 600 °C for 30 min. Sintering tests were carried out at 1250 and 1260 °C for 30 min. The heat treatments then performed on the samples showed the best combination of properties: 1250 MPa and 888 HV.

Rapid synthesis of ternary carbide Ti3SiC2 through pulse-discharge sintering technique from Ti/Si/TiC powders

Ti/Si/TiC powders with molar ratios of 1:1:2 (M1) and 2:2:3 (M2) were prepared for the synthesis of a ternary carbide Ti3SiC2 by using the mixture method for 24 hours in an Ar atmosphere. The synthesis process was conducted at 1200 °C to 1400 °C under a pressure of 50 MPa, using the pulse-discharge sintering (PDS) technique. After sintering, the phase constituents and microstructures of the samples were analyzed by X-ray diffraction (XRD) technique and observed by optical microscopy and scanning electron microscopy. The results showed that the phases in all the samples consisted of Ti3SiC2 and small amounts of TiC, and the optimum sintering temperature was found to be in the relatively low range of 1250 °C to 1300 °C. By the standard additive method, the relative content of Ti3SiC2 was calculated. For the M1 samples, the lowest TiC content can be only decreased to about 3 to 4 wt pct, whereas the content of Ti3SiC2 in the M2 samples is always lower than that in the M1 samples. When the M2 powder was sintered at 1300 °C for 8 to 240 minutes, the TiC peaks were found to show a very low intensity, and the corresponding content of Ti3SiC2 was calculated to be higher than 99 wt pct. The grain size of Ti3SiC2 increased from 5 to 10 µm to 80 to 100 µm in the entire applied sintering temperature range. The relative density of the M2 samples was measured to be higher than 99 pct at sintering temperatures above 1275 °C. It indicates that the PDS technique can rapidly synthesize high-content Ti3SiC2 from the Ti/Si/TiC powders in a relatively low temperature range.

Selective laser sintering of gas atomized M2 high speed steel powder

Selective laser sintering of the gas atomized M2 high speed steel powder was performed using laser powers of 2.5–100 W, scan rates of 1–30 mm/s and scan line spacings of 0.15–0.75 mm. With increasing laser power, the sintered surface varied from open/closed pores to a fully dense structure. Large lateral pores were found in the sintered surface of samples using high scan rates. For fully dense samples, smooth surfaces could be achieved using large scan line spacing. The as-supplied and sieved M2 powder particles with size ranging from 0.04 to 400 μm and 53 to 150 μm, respectively, were found to give better laser sinterability as compared with those powder particles with finer ( 150 μm) sizes.

Mechanomaking of high speed steel AISI M2: powder consolidation

AISI M2 powders were produced from the elements by mechanomaking, a room temperature process driven by high energy ball milling. The as-mechanomade powders with relative densities 0.5, were consolidated by cold and then hot isostatic pressing. Fully dense solids with carbide sizes around 20 nm are obtained after Hot Isostatic Pressing (HIP) at 950°C, while the matrix is constituted of a very fine array of crystallites below 10 nm. An as-quenched hardness of 69 HRC was obtained and a Hall-Petch behavior was observed for Vickers hardness. No evidence of residual austenite was found in either as-HIPed or quenched samples.

Mechanomaking of high speed steel AISI M2 powders fabrication

High speed steel AISI M2 was obtained by high energy milling from the elemental powders. The kinetics of synthesis were followed by Mössbauer spectroscopy and X-ray diffraction. About 14 h are required to complete alloying (12 at.% solute content) of the matrix and formation of carbides (M6C and Fe3C) all having grain sizes below 20 nm. The mean particle size was 50 μm and the individual particles were almost fully dense. Limited grain growth to <100 nm at temperatures up to 1300°C was observed. This new concept for the fabrication of alloys and materials is suggested to be termed mechanomaking.

合金粉および混合粉の焼結体を圧延した高強度Ｐ／Ｍアルミニウム合金板の諸性質

P/M 7091 alloy sheets were rolled directly from sintered compacts, and the properties of the sheets were investigated. The alloy powder, and the mixed powders M1 and M2 having same composition of 7091 alloy were used for starting powders. M1 was the mixture of AI-Zn-Co mother alloy, Al-Mg mother alloy, Al-Cu mother alloy and Al elemental powders. M2 was the mixture of Al-Co mother alloy, Zn, Mg and Cu elemental powders. The green compacts of the alloy powder and the M1, M2 powders were sintered 803-863 K for 1 h in N2. The sintered compacts were hot rolled and cold rolled, then were heat treated to T6 condition. Results obtained were as follows:1) While the cracking of P/M sheets often occurred during hot rolling process when they were made from 7091 alloy powder and mixed powder M1. The cracking of the sheet from mixed powder M2 was not observed.2) The highest UTS and elongation values of the P/M sheets rolled from sintered compacts in this study were about 590MPa and 11%, but these values were lower than those of the P/M sheets rolled from degassed and hot pressed compacts of 7091 alloy powder.3) Hydrogen contents of the P/M sheets rolled from sintered compacts decreased with increasing the sintering temperature. And it was less than 2 p.p.m., for the sheets rolled from compacts sintered at 863 K.