Steels with Different Carbon Content for High Pressure Die Casting in Semisolid State

Küthe, Fabian; Afrath, Carsten; Bührig–Polaczek, Andreas

doi:10.4028/3-908451-26-4.708

Cited by 3 publications

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“…Among others the X210CrW12 high carbon steel shows the broadest semisolid temperature at relatively low temperature range [3]. This steel has been recently a subject of investigation of semisolid forging and compression tests [4][5][6]. It was found that the steel after quenching consists of austenitic microstructure surrounded by the eutectic [4].…”

Section: Introductionmentioning

confidence: 96%

“…The increase of temperature and holding time leads to a decrease of load to deform a sample [5]. The previous works used mainly thixoforging process [4][5][6], while in the present paper a thixo-process was used where previously deformed material was heated in a ceramic cylinder and then pressed out by a piston in a semi-solid state into a hot mould. The microstructure of the obtained product was investigated by optical and electron microscopy in order to determine the size, dimensions and composition of globules as well as the microstructure and crystal structure of the eutectic components surrounding globules.…”

Section: Introductionmentioning

confidence: 98%

“…Due to higher process temperatures than in SemiSolid Metal SSM forming of aluminum and magnesium there are many problems with estimation of liquid fraction, tool material and process routes [2,3]. However, several attempts have been made for SSM processing of steels containing from 0.4 -2.5% of C [1][2][3][4][5][6][7] in the search for a convenient semi-solid temperature interval. Among others the X210CrW12 high carbon steel shows the broadest semisolid temperature at relatively low temperature range [3].…”

Section: Introductionmentioning

confidence: 99%

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Thixoforming technology of high carbon X210CrW12 steel

2009

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Several samples were cast using thixoforming method. The feedstock used was a hot rolled commercial bar of the steel X210CrW12 with the following chemical composition: 2,11 %C, 10,5 %Cr, 0,7 %W, 0,4 %Si. An apparatus was constructed allowing the thixoforming of steel parts in a protective argon atmosphere and at a high piston velocity powered by a high pressure air. It was designed and built in such a way to allow first pumping air out and argon in, fast heating of a feedstock using high frequency generator, stamping of semi liquid sample at a high piston rate of a few m/s with in earlier resistance heated mould and simultaneous control of sample and mould temperature to ±1 o C. The liquid fraction was determined using Differential Scanning Calorimetry (DSC). Observation of the microstructure was performed using optical and transmission electron microscopy. It showed a globular structure in the material, when pre-heated to the temperature of 1230ºC at a liquid fraction of 30%. After several experiments with various sample and mould temperatures, a desired globular microstructure after a thixoforming process was obtained. Basic technological parameters which permit the complete filling of the die and a useful microstructure, such as piston velocity, temperature of the die, were elaborated. The microstructure after the thixoforming process showed globular structures with a size of 50 to 200µm of the oval particles of the austenite within an eutectic matrix. The crystal structure of globules was mainly austenite and that of the eutectic ferrite and M 7 C 3 carbide.

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Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Thixoforming technology of high carbon X210CrW12 steel

2009

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“…Additionally to the decreased thermal load of the dies, a distinctly smaller reactivity of the steel with atmospheric gases results. With the STC-concept it is possible to reduce the oxidization of the steel billets surface during inductive heating and transport to the shot chamber, for that a virtually scale free billet can be processed [5,8]. This can be achieved by an encapsulation of the billet with a vacuum formed Al 2 O 3 /SiO 2 tube.…”

Section: Introductionmentioning

confidence: 99%

Properties of Thixocast Spring Steel Ratchets

Bünck

Bührig–Polaczek

2012

SSP

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Forging is state of the art for the production of hand tools in industrial scales. Due to high demands on stiffness and fracture toughness high-strength forged steels are used to provide components with high mechanical load capacity. In spite of all advantages forging is restricted by some means like the freedom of scope. However, because of the extreme thermal load and the hardly avoidable casting defects, hand tools are nowadays not cast. By thixocasting steel technical difficulties can be reduced and new options are provided, which allow manufacturing of components with much higher complexity than forging. During this work ratchets were thixocast successfully using spring steel type 61SiCr7. Based on the STC-concept, a new method to prevent the shot sleeve from damage was tested. Dies made of hot forming tool steel X38CrMoV5 were optimized by simulation and coated by plasma chemical deposition of crystalline Al2O3 protective coatings. The cast parts were heat treated successfully to enhance the toughness, which was measured by tensile and Charpy impact tests.

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Steels with Different Carbon Content for High Pressure Die Casting in Semisolid State

Küthe

Afrath

Bührig–Polaczek

2006

SSP

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Some excellent projects have been finished successfully since the last conference on the pre-industrial stage showing the great potential of thixoforming technology for steels [1][2]. Experiments presented in this paper on induction heating, process window and mould filling of three widely-used steel alloys offer an even greater field of application for industrial companies. In the past thin walled cutting tools and complex impellers made of cold working steel X210CrW12 were produced at the Foundry Institute [3][4]. Constitutive on this knowledge the field of applications is enlarged by research on two further steel alloys. Processing of 100Cr6 (roller bearing steel) and 42Cr4 (annealing steel) is challenging due to a decreasing window at a higher temperature level with decreasing carbon content. An exact procedure has been worked out to create new control programs for the induction heating unit. It is based on thermo-chemical calculations and delivers billets with feasible temperature distribution and well defined content of liquid phase. Material characterization is performed in a step-die (seven steps between 25 and 0.5mm), especially developed for demands of semi-solid casting. Mould filling capacity, micro structural evolution and mechanical properties are determined on each of the seven steps. For any reproducible process the knowledge of suitable system parameters is essential. To find the limits of the process window sensitive experimental parameters were changed systematically for each of the three steel alloys. In addition to tool temperature the process windows consist principally of content of liquid phase fs, piston velocity vP and pressure during freezing pfr. Characteristic differences appeared between the different steel grades. The thermal simulation was used to find functional dimensions for the gating system and to shorten process times. Simulation of tools system was used to estimate the additional thermal load induced by higher working temperatures. The abrasive wear at the offsets to the next steps was in the same order of magnitude for all examined steels. These results provide the opportunity for commercial steel grades to cast complex steel parts in high pressure die casting.

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Steels with Different Carbon Content for High Pressure Die Casting in Semisolid State

Cited by 3 publications

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Thixoforming technology of high carbon X210CrW12 steel

Thixoforming technology of high carbon X210CrW12 steel

Properties of Thixocast Spring Steel Ratchets

Steels with Different Carbon Content for High Pressure Die Casting in Semisolid State

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