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1

Modification of Cr-Mo low alloyed steels by addition of Mn via mechanical milling

Sicre-Artalejo J., Campos M., Torralba J. M.

Journal of Achievements in Materials and Manufacturing Engineering

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2008

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Vol. 28, nr 2

199-202

EN

Purpose: The PM industry is in continuous development due to the necessity to increase its potential and competitiveness. This fact and the demand for substituting certain alloying elements used so far, require the addition of new alloying elements and new processes leading to and optimization of costs, strength and tolerances. A different method for introducing Mn into the alloying system is proposed in the present work. Mechanically-blending and mechanically alloying Mn containing master alloys are generated and based on three different steels grades, ASC100.29 (plain iron), Astaloy CrL and Astaloy Mo (pre-alloyed systems). Design/methodology/approach: To profit Mn sublimation effects, small Mn particles, in order to increase the specific surface available to sublimate, must be homogenously added. Different milling times are considered in order to attain the desired master alloys containing 50% of Mn which is diluted in each base powder by normal mixing. New alloying systems were then pressed to a green density of 7.1 g/cm3 and sintered at 1120 ° C in 90N2-10H2 atmosphere. STA showed Mn diffusion during sintering and a densification enhancement. Findings: The sublimation of Mn during sintering provides some specific phenomena which facilitate the sintering of alloying elements with high oxygen affinity. The resulting mechanical properties and the microstructures must be discussed considering the high energy stored in the master alloy which favours the mass transport mechanism during sintering. Research limitations/implications: Research is being continued with the optimisation of the mechanical properties and the application of heat treatments taking the profit of the increase of the hardenability induced by Mn. Originality/value: Mn seems a viable substitute for alloy elements used so far in PM, such as Ni and Mo. Following European regulations Ni cannot be used in its elemental powder form because of its effects on health and Mo has increased its price in the last years.

2

The impact of production methods on the properties of gradient tool materials

Dobrzański L. A., Kloc-Ptaszna A., Matula G., Contreras J. M., Torralba J. M.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 24, nr 2

19-26

EN

Purpose: The goal of this work is to obtain the gradient materials based on the non-alloyed steel reinforced highspeed steel using the conventional powder metallurgy method and pressureless forming powder metallurgy. Design/methodology/approach: Forming methods were developed during the investigations for high-speed and unalloyed steel powders, making it possible to obtain materials with six layers in their structure. The non-alloyed steel was fabricated by mixing iron powders with graphite. Findings: It was found out, basing on the hardness tests, that the layer built of steel without any alloy elements demonstrates very low hardness in comparison with the transition layer and the HS6-5-2 high-speed layer. The density of the specimens rises with increasing temperature. It was also observed that porosity decreases along with the carbon content in these layers. Practical implications: It was noticed, that increase of the sintering temperature results in the uncontrolled growth and coagulation of the primary carbides and melting up to forming of eutectics in layers consisting of the high-speed steel. Developed material is tested for turning tools. Originality/value: The layers were poured in such way that the first layers consisted of the non-alloy steel and the last one from the high-speed steel, and were compacted next. The layers inside the material are mixes of the high-speed steel and non-alloy steel powders in the relevant proportions.

3

Structure and properties of HS6-5-2 type HSS manufactured by different P/M methods

Matula G., Dobrzański L. A., Herranz G., Várez A., Levenfeld B., Torralba J. M.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 24, nr 2

71-74

EN

Purpose: It has been demonstrated in the paper structure and properties of high speed-steel HS6-5-2 type manufactured by different method of powder metallurgy. Design/methodology/approach: Light microscope, SEM, image analysis, hardness tests, density examination, transverse rupture strength tests, analysis of chemical composition by LECO apparatus. Findings: Basing on the investigations of the HS6-5-2 type high-speed steels reinforced with ceramics particles fabricated with Powder Metallurgy it was found of that density of sintered samples depend on reinforced particles, temperatures and atmosphere of sintering. Increasing of sintering temperature increase the density of sintering samples. Moreover the sintering under N2-10%H2 atmosphere produce samples with higher quality than using argon atmosphere and prevent of surface oxidation during sintering. Practical implications: The modern methods of powder metallurgy gives the possibility to manufacturing tool materials on the basis of high speed-steel which characterised very good properties with their final shape. Originality/value: In the paper the manufacturing by modern PM methods of tool materials on basis of high speed-steel manufactured carried out in order to improve the structure and properties of tool materials and to produce tools with their final shape.

4

Structure and properties of gradient tool materials with the high-speed steel matrix

Dobrzański L. A., Kloc-Ptaszna A., Matula G., Torralba J. M.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 24, nr 2

47-50

EN

Purpose: This work concerns research on the structure and properties of gradient tool materials with the HS6-5-2 high-speed steel matrix reinforced by the tungsten carbide. Design/methodology/approach: The materials were fabricated using the conventional powder metallurgy method, consisting in compacting the powder in a closed die, and subsequent sintering. All the sintered test pieces were subjected to examination of density, porosity, and hardness; observations were also made using the scanning electron microscope (SEM), equipped with the back-scatter electrons detector (BSE) and the dispersive energy analyser (EDAX D4). Findings: The density of the compacted and sintered test pieces grows along with the sintering temperature increase. The porosity grows along with the WC content growth in the particular layers. It was observed that the sintering time has an effect on the porosity growth. The longer the sintering time is, the higher the porosity is. The HRA hardness of the compacted and sintered test pieces grows along with the sintering temperature increase. It was noted that application of a longer sintering time results in slight hardness lowering. Practical implications: Developed material is tested for turning tools. Originality/value: The material presented in this paper has layers consisting of the carbide-steel with growing hardness on one side, and on the other side the high-speed steel, characterized by a high ductility.

5

Effect of WC concentration on structure and properties of the gradient tool materials

Dobrzański L. A., Kloc-Ptaszna A., Dybowska A., Matula G., Gordo E., Torralba J. M.

Journal of Achievements in Materials and Manufacturing Engineering

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2007

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Vol. 20, nr 1-2

91-94

EN

Purpose: The goal of this work is to obtain the contemporary gradient materials based on the tungsten carbide reinforced high-speed steel using the conventional powder metallurgy method and increasing the high-steel hardness (80 HRA = 800 HV) by introducing the tungsten carbide as the reinforcing phase, with hardness exceeding 2200 HV. Design/methodology/approach: The materials were fabricated with the conventional powder metallurgy method consisting in compacting the powder in the closed die and finally sintering it. Forming methods were developed for powders of the HS6-5-2 high speed steel and WC, making it possible to obtain material with seven layers in the structure. Findings: It was found out basing on the microhardness tests that hardness of test pieces grows along with the sintering temperature and with WC content in the interface layers and in the high-speed steel ones. It was also observed that porosity decreases along with the WC concentration increase in these layers. It was found out, basing on the comparison of structures and properties of the compacted and sintered test pieces, that in structures of all examined test pieces in the sintered state fine carbides occurred distributed homogeneously in the high-speed steel layer. Research limitations/implications: It was noticed, that increase of the sintering temperature results in the uncontrolled growth and coagulation of the primary carbides and melting up to forming of eutectics in layers consisting of the high-speed steel. Practical implications: Material presented in this paper has layers consisting on one side from the mix of the high-speed steel and WC, and on the other side the high-speed steel, characteristic of the high ductility. Such material is tested for milling cutters. Originality/value: The layers were poured in such way that the surface layer consists of the mix of the high-speed steel and WC, and the middle one from the high-speed steel. The layers inside the material are mixes of the high-speed steel and WC in the relevant proportions.

6

Characteristics of structure and properties of a sintered graded tool materials

Dobrzański L. A., Kloc-Ptaszna A., Matula G., Torralba J. M.

Inżynieria Materiałowa

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2007

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Vol. 28, nr 3-4

138-141

EN

The goal of this work is the characterization of structure and properties of a graded tool materials. The materials were fabricated by using the conventional powder metallurgy method, consisting in compacting the powder in a closed die and sintering it. Forming methods were developed for the HS6-5-2 high-speed steel and non-alloy steel powders, making it possible to obtain materials with six layers in their structure. The powders were poured into the die so that the first layer consisted of the non-alloy steel and the last one consisted of the high-speed steel. The layers inside the material are mixes of the high-speed steel and non-alloy steel powders in relevant proportions. The pieces were sintered at the same temperature and over the same time, but in different atmospheres. The sintered parts were subjected to examinations of density, porosity, and Vickers and Rockwell hardness. Observations were also made, using the scanning electron microscope (SEM) equipped with the back-scatter electrons detector (BSE) and dispersive energy analyser (EDAX D4).

PL

Celem niniejszej pracy jest scharakteryzowanie struktury i własności narzędziowych materiałów gradientowych. Do wytwarzania materiałów została zastosowana konwencjonalna metoda metalurgii proszków polegając na prasowaniu proszku w matrycy zamkniętej i następnym spiekani Opracowano metody formowania proszków stali szybkotnącej typu HS6-5-i stali niestopowej, umożliwiające otrzymanie materiału z sześcioma warstwami w strukturze. Warstwy były wsypywane do matrycy w ten sposób, że pierwsza warstwa składa się ze stali niestopowej, a ostatnia ze sta szybkotnącej. Warstwy wewnątrz materiału są mieszaninami proszków stali szybkotnącej i stali niestopowej, w odpowiednich proporcjach. Próbki spiekano w tej samej temperaturze i czasie, lecz w innej atmosferze. Spieki poddano pomiarom gęstości, porowatości i twardości w skali Vickersa i Rockwella oraz przeprowadzono obserwacje na elektronowym mikroskop skaningowym (SEM) wyposażonym dodatkowo w detektor elektronów wstecznie rozproszonych (BSE) i analizator energii dyspersyjnej (EDAX D4).

7

Structure of the gradient carbide steels of HS 6-5-2 high-speed steel matrix

Dobrzański L. A., Kloc-Ptaszna A., Matula G., Torralba J. M.

Archives of Materials Science and Engineering

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2007

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Vol. 28, nr 10

589-592

EN

Purpose: The goal of this work is to obtain gradient carbide steels based on a high-speed steel reinforced with tungsten carbide. Design/methodology/approach: The materials were fabricated using the conventional powder metallurgy method. The gradient carbide steels was fabricated by mixing high-speed steel with WC powders. The uniaxial pressing before sintering was used for manufacturing the materials, consisting in compacting the powder in a closed die, and subsequent sintering. The sintered test pieces observations were also made using the scanning electron microscope (SEM), equipped with the back-scatter electrons detector (BSE) and the dispersive energy analyser (EDAX D4). Findings: It was observed that the as-sintered properties of gradient carbide steels are strongly affected by the tungsten carbide content. Practical implications: Developed material is tested for cutting tools. Originality/value: The material presented in this paper has layers, at one side consisting of the high-speed steel, characterized by a high ductility and at the other side the carbide steel characterized by a higher hardness. A forming methods were developed for high-speed and WC powders, making it possible to obtain materials with seven layers in their structure.

8

Structure and properties of the gradient tool materials of unalloyed steel matrix reinforced with HS6-5-2 high-speed steel

Dobrzański L. A., Kloc-Ptaszna A., Matula G., Torralba J. M.

Archives of Materials Science and Engineering

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2007

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Vol. 28, nr 4

197-202

EN

Purpose: The goal of this work is to obtain the gradient materials based on the non-alloyed steel reinforced highspeed steel using the pressureless formed method. Design/methodology/approach: The non-alloyed steel was fabricated by mixing iron powders with graphite. The unalloyed steel contains 0.5% carbon. The pressureless powder forming was used for manufacturing the materials. Findings: It was found out, basing on the hardness tests, that the layer built of steel without any alloy elements demonstrates very low hardness in comparison with the transition layer and the HS6-5-2 high-speed layer. It was also found, that the density rises with increasing temperature. The portion of pores in the particular layers of the gradient materials decreases along with the carbon concentration increase in particular layers. Practical implications: The material presented in this paper has layers, at one side consisting of the nonalloy steel with hardness growing with the increase of carbon content, and at other side the high-speed steel, characterized by a high ductility. Developed material is tested for turning tools. Originality/value: A forming methods were developed for high-speed and non-alloy steel powders, making it possible to obtain materials with three layers in their structure. Investigations included determining the sintering conditions, especially the temperature and treatment cycle, as well as examining selected mechanical properties.

9

Influence of the chemical composition and particle size of the metal matrix, on TiCN-reinforced Fe-based composites

Gómez B., Gordo E., Ruiz-Navas E. M., Torralba J. M.

Journal of Achievements in Materials and Manufacturing Engineering

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2006

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Vol. 17, nr 1-2

57-60

EN

Purpose: The objective of this work is to study the influence of different parameters as the chemical composition and particle size of the metal matrix, on TiCN-reinforced Fe-based composites. Design/methodology/approach: In order to obtain the composite powder two different types of blending were used, conventional blending and high energy milling (HEM). The HEM was carried out in a planetary ball mill during 12 hours, with a rotating speed of 400 rpm, and a ratio ball:powder of 10:1 (in mass). The atmosphere was Argon to prevent the oxidation. After the preparation of powders, compacts were produced by uniaxial pressing at 700 MPa and sintering under vacuum. The sintering temperatures varied between 1350oC and 1450oC, for 60 min. Sintered samples were characterised by determination of density, dimensional change, Vickers hardness (HV30), bending strength, and C, N contents (by LECO). The microstructural study was carried out by scanning electron microscopy (SEM). Findings: As a result of the study it is clear that the presence of carbides in the metal matrix allows the increasing of mechanical properties of sintered composites, and these properties are related with the microstructure and C/N ratio. Practical implications: In this research 50 % vol of hard phase is introduced, following a simpler and lowercost route, as pressing and sintering. It is true that high-energy milling raises the cost of the processing. This is why conventional blending of small size powder particle has also been done in this work. The latter route has shown to give quite promising results, reaching hardness values about 2000 HV30. Originality/value: In this work, composite materials with high hardness have been obtained following a simple and low-cost route.

10

Effect of carbon concentration on structure and properties of the gradient tool materials

Dobrzański L. A., Kloc A., Matula G., Domagała J., Torralba J. M.

Journal of Achievements in Materials and Manufacturing Engineering

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2006

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Vol. 17, nr 1-2

45--48

EN

Purpose: The goal of this project is development of the contemporary gradient materials using the powder metallurgy methods to ensure the required properties and structure of the designed material. Design/methodology/approach: The materials were fabricated with the conventional powder metallurgy method consisting in compacting the powder in the closed die and finally sintering it. Forming methods were developed for the HS6-5-2 high-speed steel and non-alloy steel powders, making it possible to obtain materials with three layers, and later - after their further modification - with six layers in their structure. Findings: It was found out basing on the microhardness tests that hardness of test pieces grows along with the sintering temperature and with carbon content in the interface and non-alloy layers. It was also observed that porosity decreases along with the carbon content in these layers. It was found out, basing on the comparison of structures and properties of the compacted and sintered test pieces, that in structures of all examined test pieces in the sintered state fine carbides occurred distributed homogeneously in the high-speed steel layer. Research limitations/implications: It was noticed, that increase of the sintering temperature results in the uncontrolled growth and coagulation of the primary carbides and melting up to forming of eutectics in layers consisting of the high-speed steel. Practical implications: Material presented in this paper has layers consisting on one side from the non-alloy steel with hardness growing with the increase of carbon content, and on the other side the high-speed steel, characteristic of the high ductility. Such material is tested for turning tools. Originality/value: The layers were poured in such way that the first layers consisted of the non-alloy steel and the last one from the high-speed steel, and were compacted next. The layers inside the material are mixes of the high-speed steel and non-alloy steel powders in the relevant proportions.

11

Wpływ stężenia węgla na strukturę i własności gradientowych materiałów narzędziowych

Dobrzański L. A., Kloc-Ptaszna A., Matula G., Torralba J. M.

Archiwum Odlewnictwa

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2006

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R. 6, nr 21/1

141-148

PL

Celem niniejszej pracy jest opracowanie nowoczesnych materiałów gradientowych z wykorzystaniem konwencjonalnych metod metalurgii proszków, w celu zapewnienia wymaganych własności i struktury projektowanego materiału. Prezentowany materiał gradientowy posiada z jednej strony warstwę ze stali niestopowej, a z drugiej strony - warstwe ze stali szybkotnącej, charakteryzującej się dużą ciągliwością. Pomiędzy nimi znajdują sie warstwy przejściowe o wzrastającej zawartości węgla (twardości). Materiał taki testowany jest na noże tokarskie.

EN

The goal of this project is development of the contemporary gradient materials using the powder metallurgy methods to ensure the required properties and structure of the designed material. Material presented in this paper has layers consisting on one side from the non-alloy steel with hardness growing with the increase of carbon content, and on the other side the highspeed steel, characteristic of the high ductility. Such material is tested for turning tools.

12

Wpływ metody formowania na strukturę i własności spiekanych stali szybkotnących

Dobrzański L.A., Matula G., Levenfeld B., Varez A., Torralba J.M.

Inżynieria Materiałowa

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2003

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R. XXIV, nr 6

597-600

PL

W pracy wykazano, że stale doświadczalne typu HS6-5-2 i HS12-1-5-5 wytwarzane metodą formowania gęstwy polimerowo-proszkowej (PIM) cechują się niższą temperaturą spiekania w stosunku do tych samych gatunków stali wytwarzanych przez prasowanie i spiekanie (PM). Stwierdzono, że wyższą gęstość, bardziej jednorodną strukturę z drobnymi wydzieleniami faz węglikowych otrzymuje się podczas spiekania stali formowanych z gęstwy w atmosferze mieszanki gazów ochronnych.

EN

In that paper it has been demonstrated that experimental steels of the HS6-5-2 and HS12-1-5-5 type made by the polymer-powder slurry forming (PIM) characterised by a lower sintering temperature, in relation to the same steel grades manufactured by compaction and sintering (PM). It has been found out that higher density, more homogeneous structure with fine precipitations of carbide phases are obtained during sintering of steels formed out of the slurry in the atmosphere of inert gases.