The Rheological Behavior of HS6-5-2 Tool Steel for Non-Isothermal Processing

2012 ◽  
Vol 192-193 ◽  
pp. 317-322
Author(s):  
Farzad Hosseini Yekta ◽  
S.A. Sadough ◽  
Vahid Pouyafar ◽  
Amin Jabbari
Keyword(s):  
Shear Rate ◽  
Cooling Rate ◽  
Tool Steel ◽  
Solid Fraction ◽  
Rheological Behavior ◽  
Liquid Fraction ◽  
Outer Cylinder ◽  
Processing Temperature ◽  
Applied Torque ◽  
Semi Solid

The rheological behavior of semi-solid tool steel is investigated using a conventional rheometer under cooling rate and shear rate. The processing of steels in semi-solid state is still at development stage due to the high processing temperature involved. The candidate grades of steel for thixoforming are high speed, high carbon, stainless steel and ductile iron. TheHS6-5-2 tool steel has a wide semi-solid range of over 200 C and the required spheroidal microstructure achieved by partial re-melting from as supplied state without any mechanical agitation, indicated the potential of this grade to be investigated in semi-solid processing. For non-isothermal processing an increase of solid fraction related to solidification due to thermal exchanges is observed. In the first series of experiment after melting the feed stock in an alumina cup, the alloy is sheared continuously by a rotating rod with a constant shear rate under three different cooling rates to the 55% corresponding liquid fraction. In the second series of experiment three different shear rates were applied under a constant cooling rate. The apparent viscosity of the slurry as a function of cooling rate and solid fraction is calculated from the applied torque to the outer cylinder. The results show that the slurry viscosity decreases with increasing shear rate and increases with increasing cooling rate and solid fraction. Additionally for a given solid fraction, shear thinning behavior is observed.

Rheological Behavior of Semi-Solid Slurry of A356 Alloy at High Shear and Cooling Rates

2008 ◽  
Vol 141-143 ◽  
pp. 409-414 ◽  
Author(s):  
N. Barman ◽  
P. Dutta
Keyword(s):  
Shear Rate ◽  
Cooling Rate ◽  
Solid Fraction ◽  
Rheological Behavior ◽  
Outer Cylinder ◽  
A356 Alloy ◽  
High Shear ◽  
Concentric Cylinder ◽  
Cooling Rates ◽  
Series Of Experiments

The rheological behavior of semisolid aluminium alloy (A356) slurry is investigated by using a concentric cylinder viscometer under high cooling rate (30 to 50°C/min) and high shear rate (650 to 1500s-1) conditions. Two different series of experiments are carried out. In all of these experiments, the pellets of A356 alloy are poured into the outer cylinder where they melt completely by resistance heating. When the inner cylinder is placed concentrically, the molten metal resides in the annular space between the cylinders. As the inner cylinder rotates, the alloy is sheared continuously during cooling from a temperature of 630°C, and a slurry forms. In the first series of experiments, for different cooling rates, shearing continues under a constant shear rate until rotation of the inner cylinder stops. During experiments, the temperature of the slurry is measured continuously using a K-type thermocouple, from which the solid fraction is calculated. In the second series of experiments, the molten alloy is cooled and sheared continuously at different shear rates for a given cooling rate. The apparent viscosity of the slurry is calculated by measuring the torque applied to the inner cylinder and its rotational speed. The results show that the slurry viscosity increases with increasing fraction of solid and increasing cooling rate, and it decreases with increasing shear rate. At high values of shear and cooling rates, the viscosity varies gradually up to a solid fraction of about 0.5.

Rheological Behavior and Fluidity of Semi-Solid SiCp/A357 Composites with Different SiC Addition Levels

2016 ◽  
Vol 256 ◽  
pp. 126-132 ◽  
Author(s):  
Zhen Lin Zhang ◽  
Zhi Feng Zhang ◽  
Jun Xu ◽  
Wei Min Mao
Keyword(s):  
Shear Rate ◽  
Solid Fraction ◽  
Rheological Behavior ◽  
Apparent Viscosity ◽  
Stir Casting ◽  
Sic Particles ◽  
Semi Solid ◽  
Test Casting ◽  
Good Agreement

The apparent viscosities of the semi-solid SiCp/A357 composites with 0vol.%, 10vol.% and 20vol.% SiC particles manufactured by stir casting were investigated using a Couette type viscometer, and the composite fluidity was examined with a test casting. The results showed that, the viscosities of the semi-solid SiCp/A357 composites decreased with an increase in shear rate, but increased with the increasing of solid fraction, and apparent viscosity of 10vol.% SiCp/A357 composite was the lower than that of 20vol.% SiCp/A357 composite at the same solid fraction; and the composite fluidity results were in a good agreement with the viscosity ones.

A Study of Microstructure Properties of AISI D2 Tool Steel in Partial Re-Melting Method

2014 ◽  
Vol 699 ◽  
pp. 76-80 ◽  
Author(s):  
M.N. Mohammed ◽  
M.Z. Omar ◽  
J. Syarif ◽  
Z. Sajuri ◽  
M.S. Salleh ◽  
...  
Keyword(s):  
Tool Steel ◽  
Liquid Fraction ◽  
Cold Work ◽  
Industrial Applications ◽  
Melting Method ◽  
Shaping Process ◽  
Aisi D2 ◽  
Semi Solid ◽  
Net Shaping ◽  
Aisi D2 Tool Steel

Due to the growing demand for cold-work tool steel in various industrial applications, it is crucial to improve the fabrication technique, because complex shapes involve an extensive and costly workshop effort. Hence, a one-step net-shaping process, such as the semi-solid forming, could offer great benefits. With the aim of finding a minimum process chain for the manufacturing of a high-quality production, the microstructural evolution of the ledeburitic AISI D2 tool steel in the semi-solid-state was studied experimentally via the Direct Partial Re-Melting Method (DPRM). Samples were heated in an argon atmosphere up to 1255°C, which corresponded to about 16% of liquid fraction, and held for 0 minute. The microstructural observation after DPRM showed that the equiaxed austenite grains are observable within a small liquid matrix. The microstructure also contains primary, non-dissolved carbides with a new, precipitated eutectic.

Rheological Behavior of Various Al Alloys during Solidification

2012 ◽  
Vol 710 ◽  
pp. 35-42
Author(s):  
Michel Suéry
Keyword(s):  
Ductile Fracture ◽  
Cooling Rate ◽  
Solid Fraction ◽  
Rheological Behavior ◽  
Liquid Films ◽  
Al Alloys ◽  
Tensile Behavior ◽  
Controlled Cooling ◽  
Sharp Transition ◽  
Solid Specimen

This paper is concerned with the tensile behavior of various Al alloys during solidification obtained by using an initially solid specimen heated locally until it becomes fully liquid and then partially solidified at a controlled cooling rate. It is shown that for Al-Cu as well as for Al-Si-Mg alloys, a similar behavior is observed with a sharp transition on the stress-solid fraction curve when the coalescence solid fraction of the dendrites is reached. Below the transition fracture occurs along liquid films for very low stresses whereas beyond this transition, ductile fracture is observed leading to higher stresses.

scholarly journals Application of X-Ray Microtomography to Quantify the Liquid Fraction of M2 Steel for Semi-Solid Forming Process

2013 ◽  
Vol 554-557 ◽  
pp. 547-552 ◽  
Author(s):  
Guo Chao Gu ◽  
Raphaël Pesci ◽  
Eric Becker ◽  
Laurent Langlois ◽  
Régis Bigot
Keyword(s):  
Mechanical Properties ◽  
Solid State ◽  
Liquid Fraction ◽  
High Energy ◽  
Material Behavior ◽  
Model Alloy ◽  
Processing Temperature ◽  
Volume Percentage ◽  
X Ray ◽  
Semi Solid

Thixoforging, one variant of semi-solid metal processing in which the metallic alloys are processed at low liquid fraction (0.1< Fl < 0.3), is used to produce complex parts with high mechanical properties. Steel thixoforging faces more challenges as compared to that of low melting point materials due to high processing temperature and lack of understanding of the thermomechanical behavior of materials in the given conditions. It is crucial to study the microstructure at the semi-solid state to improve the understanding of the thixoforging process since the material behavior strongly depends on main parameters: the liquid fraction, its distribution as well as the coherence of the solid skeleton. The microstructure has a great influence on the viscosity of the material, on the flows and finally on the final shape and mechanical properties of the thixoforged parts. Here, the characterization of the volume percentage and distribution of liquid fraction at the semi-solid state with high energy 3D X-ray microtomography was investigated on M2 steel grade as a ‘model’ alloy. The obtained results have been compared to 2D observations using EDS technique in SEM on heated and quenched specimens. They showed a good correlation making both approaches very efficient for the study of the liquid zones at the semi-solid state.

The Interface Morphology of Thixo-Joined Cold Work Tool Steel

2014 ◽  
Vol 663 ◽  
pp. 276-280
Author(s):  
M.N. Mohammed ◽  
Mohammed Zaidi Omar ◽  
Junaidi Syarif ◽  
Zainuddin Sajuri ◽  
M. Shukor Salleh ◽  
...  
Keyword(s):  
Tool Steel ◽  
Liquid Fraction ◽  
Cold Work ◽  
Smooth Transition ◽  
Joint Interface ◽  
Dendritic Microstructure ◽  
Aisi D2 ◽  
Semi Solid ◽  
Welding Processes ◽  
Cold Work Tool Steel

Cold-work tool steel is considered to be a nonweldable metal due to its high percentage content of carbon and alloying elements. The application of a new process of the semi-solid joining of two parts of AISI D2 cold-work tool steel is proposed using a partial remelting method. Samples were heated in an argon atmosphere up to 1275°C which corresponded to about 20% of liquid fraction and held for 10 minutes. Metallographic analyses along the joint interface showed a smooth transition from one to the other and neither oxides nor micro-cracking was observed. The current work successfully confirmed that avoidance of a dendritic microstructure in the semi-solid joined zone and high bonding quality components can be achieved without the need for force or complex equipment when compared to conventional welding processes.

Evolution of Globular Microstructures during Direct Partial Re-Melting Experiment of AISI D2 Tool Steel

2013 ◽  
Vol 465-466 ◽  
pp. 829-833 ◽  
Author(s):  
M.N. Mohammed ◽  
Mohd Zaidi Omar ◽  
Junaidi Syarif ◽  
Zainuddin Sajuri ◽  
Mohd Shukor Salleh ◽  
...  
Keyword(s):  
Tool Steel ◽  
Liquid Fraction ◽  
Cold Work ◽  
Surface Oxidation ◽  
Eutectic Carbides ◽  
Average Grain Size ◽  
Aisi D2 ◽  
Semi Solid ◽  
Semisolid Process ◽  
Cold Work Tool Steel

Steel is a mostly challenging metal to semisolid process because of the high temperatures implicated and the prospective for surface oxidation. Slurry processing experiment was performed with AISI D2 cold work tool steel to identify the evolution of globular microstructures via Direct Partial Re-Melting Method (DPRM). Samples were heated in an argon atmosphere up to 1330°C which corresponded to about 38% of liquid fraction and held for 5 minutes. The typical microstructure after DPRM consists of globular grains (average grain size about 50μm) while the remaining interspaces were filled by precipitated eutectic carbides on the grain boundaries and lamellar network. Based on the requirements of thixoformability, the current work confirms the suitability of the AISI D2 cold work tool steel as a candidate material for semi-solid forming.

Understanding the Rheological Transitions in Semi-Solid Alloys by a Combined In Situ Imaging and Granular Micromechanics Modeling Approach

2022 ◽  
Vol 327 ◽  
pp. 127-132
Author(s):  
Te Cheng Su ◽  
Catherine O'Sullivan ◽  
Hideyuki Yasuda ◽  
Christopher M. Gourlay
Keyword(s):  
Shear Rate ◽  
Solid Fraction ◽  
Discrete Element ◽  
Quantitative Agreement ◽  
Micromechanical Modeling ◽  
Two Phase ◽  
Shear Cracking ◽  
Semi Solid ◽  
Boltzmann Method

To gain better understanding of rheological transitions from suspension flow to granular deformation and shear cracking, this research conducted shear-deformation on globular semi-solid Al-Cu alloys to study the rheological behavior of semi-solid as a function of solid fraction (38% - 85%) and shear rate (10-4 – 10-1 s-1) under real-time synchrotron radiography observation. By analyzing 17 X-ray imaging datasets, we define three rheological transitions: (i) the critical solid fraction from a suspension to a loosely percolating assembly; (ii) from the net contraction of a loose assembly to the net dilation of a densely packed assembly, and (iii) to shear cracking at high solid fraction and shear rate. Inspired by in-situ observations of semi-solid deformation showing a disordered assembly of percolating crystals in partially-cohesive contact with liquid flow, we reproduced a two-phase sample using the coupled lattice Boltzmann method-discrete element method (LBM-DEM) simulation approach for granular micromechanical modeling. In DEM, each globular Al grain is represented by a discrete element, and the flow of interstitial liquid is solved by LBM. The LBM-DEM simulations show quantitative agreement of semi-solid strain localization with the experiments and are used to explore the components involved in the shear rate dependence of the transitions, and the role of liquid pressure on the initiation of shear cracking.

On the Microstructure of XW-42 Steel after Direct Partial Remelting

2010 ◽  
Vol 154-155 ◽  
pp. 1280-1283 ◽  
Author(s):  
Afzalur Alfan ◽  
Mohd Zaidi Omar ◽  
Junaidi Syarif
Keyword(s):  
Partial Melting ◽  
Liquid Fraction ◽  
Processing Temperature ◽  
Forming Process ◽  
Annealed Condition ◽  
Partial Remelting ◽  
Average Grain Size ◽  
Pre Treatment ◽  
Semi Solid ◽  
Melting Experiment

In order to be considered as a material for semi-solid processing, an alloy has to possess solid spheroids within liquid matrix. Therefore, it is important to investigate the structure of the candidate alloy prior to forming process by conducting partial melting experiment. In this research, the partial melting was conducted for XW-42 steel directly from as annealed condition without any pre-treatment (Direct Partial Remelting). Liquid Fraction Profile obtained from Differential Thermal Analysis (DTA) showed that temperature of 1340°C was located in a low temperature sensitivity region, hence making it as a candidate for processing temperature. Direct Partial Remelting at this temperature for 0, 2 and 5 minutes revealed near spheroidal structure with average grain size between between 45-51 µm which can be considered suitable for semi-solid processing.

scholarly journals Self-diffusion scalings in dense granular flows

Soft Matter ◽  
2021 ◽  
Author(s):  
Riccardo Artoni ◽  
Michele Larcher ◽  
James T. Jenkins ◽  
Patrick Richard
Keyword(s):  
Shear Rate ◽  
Solid Fraction ◽  
Granular Flows ◽  
The Self ◽  
Granular Temperature ◽  
Restitution Coefficient ◽  
Self Diffusion ◽  
Diffusivity Tensor ◽  
Dense Granular Flows

The self-diffusivity tensor in homogeneously sheared dense granular flows is anisotropic. We show how its components depend on solid fraction, restitution coefficient, shear rate, and granular temperature.

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