Experimental and Numerical Investigation of Extrusion Die Profiles for Uniform and Effective Case-Hardening Treatment

2012 ◽  
Author(s):  
Syed Sohail Akhtar ◽  
Abul Fazal M. Arif
Keyword(s):  
Nitrogen Concentration ◽  
Compound Layer ◽  
Nitride Layer ◽  
Case Depth ◽  
Design Guidelines ◽  
Case Hardening ◽  
H13 Steel ◽  
Die Profile ◽  
Aisi H13 ◽  
Electron Microscopes

One of the utmost challenges of hot aluminum extrusion is to design the die cavities, used to extrude thin-walled profiles, by considering the effective nitriding surface treatment of the die bearing surface in terms of nitride layer uniformity. In the present study, various AISI H13 steel samples (having commonly-used profile geometric features) are manufactured using wire EDM and subsequently nitrided using two-stage controlled nitriding treatment. The uniformity and depth of nitride layers formation on these are investigated in terms of compound layer and total nitride case depth using optical and scanning electron microscopes. Finite element code ABAQUS is used to simulate the nitrding process using sequentially coupled thermo-diffusive analysis in line with experimental set up. Both experimental and numerical results are found in close agreement in terms of nitrogen concentration and corresponding micro-hardness profiles. Some design modifications are implemented in FE code for critical die profile features for uniform nitride layer development. In view of the current results, some design guidelines are suggested for effective and uniform nitride layer formation in order to secure high quality extruded product and extended die life.

Effect of Profile Corners on the Nitriding Treatment of AISI H13 Hot Extrusion Dies

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Syed Sohail Akhtar ◽  
Abul Fazal M. Arif
Keyword(s):  
Nitrogen Concentration ◽  
Hot Extrusion ◽  
Nitride Layer ◽  
Design Guidelines ◽  
H13 Steel ◽  
Extrusion Dies ◽  
Aisi H13 ◽  
Electron Microscopes ◽  
Set Up ◽  
Nitride Layers

One of the utmost challenges of hot aluminum extrusion is to design the die cavities with sharp corners (used to extrude thin-walled profiles) by considering the effective nitriding surface treatment of the die bearing surface in terms of nitride layer uniformity. In the present study, various AISI H13 steel samples (having commonly used profile geometric features) are manufactured using wire electro-discharge machining (EDM) and subsequently nitrided using two-stage controlled nitriding treatment. As a special case, corner features are investigated in terms of compound and nitride layers formation using optical and scanning electron microscopes. Finite element (FE) code abaqus is used to simulate the nitriding process using mass diffusion analysis in line with experimental set up. Both experimental and numerical results are found in close agreement in terms of nitrogen concentration and corresponding microhardness profiles. Some design modifications are implemented in FE code for corner profile features for uniform nitride layer development. In view of the current results, some design guidelines are suggested for effective and uniform nitride layer formation in order to secure high quality extruded product and extended die life.

Die Soldering Phenomenon on the H13 Tool Steel with Shot Peening and Nitriding Surface Treatment

2015 ◽  
Vol 1101 ◽  
pp. 157-163
Author(s):  
Myrna Ariati ◽  
Dwi Marta Nurjaya ◽  
Rizki Aldila
Keyword(s):  
Surface Treatment ◽  
Tool Steel ◽  
Shot Peening ◽  
Surface Hardness ◽  
Nitride Layer ◽  
H13 Steel ◽  
Gas Nitriding ◽  
Aisi H13 Steel ◽  
H13 Tool Steel ◽  
Aisi H13

Die soldering occurs when molten aluminum sticks to the surface of a die material and remains there after the ejection of the part. This resulted in low productivity and economic value in the foundry industry. Nitriding surface treatment is considered as an effective way in enhancing the service life of AISI H13 steel dies and to prevent soldering effect. The focus of this paper is to investigate the influence of three different surface conditions in terms of roughness, gas nitriding and pretreatment prior to gas nitriding on the soldering effect. Three kind of samples made of AISI H13 steel were pretreated (quenched and tempered) and followed by : shot peened, gas nitrided and shot peening followed by gas nitriding, were immersed in liquid melted ADC 12 Aluminium alloy at 30 seconds, 30 minutes, 2 hours and 5 hours, at a constant temperature of 680oC in a holding furnace. Characterizations on the surface of the steel were focused on the optical microstructure, microhardness profile, FE SEM observation and enegy dispersive spectrometry mapping. It was found that shot peening prior to nitriding gives a higher surface hardness and depth of nitride layer of H13 tool steel, 1140 HV (>70 HRC) and 120.5 μm, than the nitriding only process, 1033 HV (68 HRC) and 105 μm. The higher the hardness and depth of nitride layer expected would reduce the die soldering effect at the surface of the H13 tool steel dies. It was also found that the only shot peening treatment resulted in a tendency of soldering accompanied by the formation of intermetallic layers ; while soldering is not found on the nitrided and shot peened-nitrided samples.

Post-Discharge Nitriding: Mathematical Modeling and Numerical Simulation of the Layer Growth

2009 ◽  
Vol 289-292 ◽  
pp. 285-292
Author(s):  
F. Castillo ◽  
J. Oseguera-Peña ◽  
A. Fraguela ◽  
J.A. Gómez
Keyword(s):  
Numerical Simulation ◽  
Moving Boundary ◽  
Early Stage ◽  
Molecular Nitrogen ◽  
Nitrogen Concentration ◽  
Compound Layer ◽  
Nitride Layer ◽  
Layer Growth ◽  
Discharge Process ◽  
Post Discharge

Nitriding by microwave post-discharge process involves molecular nitrogen dissociation. It has been observed that nitrogen flux from surface to solid during the early stage does not follow a parabolic regime and that the growth rate of concomitant nitride layers is sensitive to atomic nitrogen concentration on the surface. In this work a mathematical model has been developed in order to describe the kinetics of the compound layer formation during a post-discharge nitriding process. The model is related to a moving boundary value problem and considers different stages: diffusion process, formation of the layers, layer growth and quasi-stabilization of the layer growth. Natural conditions on the nitrogen concentration consistent with the mass transfer mechanism are assumed. An analytical approximate solution of Goodman’s type is sought and numerical simulation is conducted to study the nitride layer growth.

Experimental evaluation and modelling of the boronizing kinetics of AISI H13 hot work tool steel

2021 ◽  
Vol 63 (12) ◽  
pp. 1136-1141
Author(s):  
Zahra Nait Abdellah ◽  
Brahim Boumaali ◽  
Mourad Keddam
Keyword(s):  
Compound Layer ◽  
Weight Percent ◽  
Boride Layer ◽  
H13 Steel ◽  
Aisi H13 Steel ◽  
Double Phase ◽  
Aisi H13 ◽  
Transient Zone ◽  
The Mean ◽  
Kinetics Of

Abstract In the study for this contribution, the AISI H13 hot work steel was pack-boronized between 2 and 6 h of exposure time within the temperature range of 800 – 1000 °C. The boriding agent was composed of a powder mixture containing (in weight percent): 90 % of boron carbide (B4C) and 10 % of sodium tetrafluoroborate (NaBF4). The SEM observations showed a less pronounced jagged interface between the boronized layer and the transient zone. A double phase boride layer (FeB and Fe2B) was identified over the surface of AISI H13 steel with the presence of metallic borides inside this compound layer. The mean diffusion coefficient (MDC) method was applied to analyze the growth of iron borides (FeB and Fe2B) as compact layers over the surfaces of AISI H13 steel. The boron activation energies in the two iron borides were also assessed from the present kinetic approach by assuming the Arrhenius relationships. Afterwards, the kinetic model was checked experimentally by considering two extra boriding conditions (925 °C for 1 and 3 h). Finally, the predicted layer thicknesses are in accordance with experimental measurements.

Depth distribution of martensite in plasma nitrided AISI H13 steel and its correlation to hardness

2015 ◽  
Vol 270 ◽  
pp. 266-271 ◽  
Author(s):  
S.D. Jacobsen ◽  
R. Hinrichs ◽  
I.J.R. Baumvol ◽  
G. Castellano ◽  
M.A.Z. Vasconcellos
Keyword(s):  
Depth Distribution ◽  
H13 Steel ◽  
Aisi H13 Steel ◽  
Aisi H13
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