Advanced Complex Analysis of the Thermal Softening of Nitrided Layers in Tools during Hot Die Forging

This article is devoted to the issues of thermal softening of materials in the surface layer of forging tools. The research covers numerical modeling of the forging process, laboratory tests of tempering of nitrided layers, and the analysis of tempering of the surface layer of tools in the actual forging process. Numerical modeling was supported by measuring the temperature inside the tools with a thermocouple inserted into the tool to measure the temperature as close to the surface as possible. The modeling results confirmed the possibility of tempering the die material. The results of laboratory tests made it possible to determine the influence of temperature on tempering at different surface layer depths. Numerical analysis and measurement of surface layer microhardness of tools revealed the destructive effect of temperature during forging on the tempering of the nitrided layer and on the material layers located deeper below the nitrided layer. The results have shown that in the hot forging processes carried out in accordance with the adopted technology, the surface layer of working tools is overheated locally to a temperature above 600 °C and tempering occurs. Moreover, overheating effects are visible, because the surface layer is tempered to a depth of 0.3 mm. Finally, such tempering processes lead to a decrease in the die hardness, which causes accelerated wear because of the abrasion and plastic deformation. The nitriding does not protect against the tempering phenomenon, but only delays the material softening process, because tempering occurs in the nitrided layer and in the layers deeper under the nitrided layer. Below the nitrided layer, tempering occurs relatively quickly and a soft layer is formed with a hardness below 400 HV.

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Advanced Complex Analysis of the Thermal Softening of Nitrided Layers in Tools During Hot Die Forging

10.20944/preprints202012.0019.v1 ◽

2020 ◽

Author(s):

Jakub Krawczyk ◽

Paweł Widomski ◽

Marcin Kaszuba

Keyword(s):

Numerical Modeling ◽

Surface Layer ◽

Laboratory Tests ◽

Complex Analysis ◽

Nitrided Layer ◽

Thermal Softening ◽

Effect Of Temperature ◽

Destructive Effect ◽

Forging Process ◽

Influence Of Temperature On

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Case Study of the Effect of Precoating on the Decarburization of the Surface Layer of Forged Parts during the Hot Die Forging Process

10.20944/preprints202012.0246.v1 ◽

2020 ◽

Author(s):

Paweł Widomski ◽

Maciej Zwierzchowski ◽

Artur Barełkowski ◽

Mateusz Tympalski

Keyword(s):

Surface Layer ◽

High Temperatures ◽

Induction Heating ◽

Laboratory Tests ◽

Hot Forging ◽

Forging Process ◽

Induction Heater ◽

Forged Parts ◽

Hot Die Forging

Based on tests results, the possibility of using this solution in the technique of industrial hot forging was evaluated. The results of laboratory tests have confirmed that lubrication of metal pieces is sufficient as well as proved it to be effective in reducing decarburization of the surface layer. Research works conducted in an induction heater showed differences in decarburization depending on a substance and concentration of lubricants that were used. These differences become more apparent when observing the surface layer of the forged parts. Results indicate that decarburization may be reduced to a minimum when we use Bonderite product in a concentration of 66% and 50%. Another lubricant, Berulit 913, may also be used. However, due to burning graphite in high temperatures, reduction of decarburization goes only as far as half of the thickness of the decarbonized layer. Condursal has no significant effect; nevertheless, it protects over the induction heating stage.

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The influence of thickness of CrN coating on the durability of hot forging dies

Open Engineering ◽

10.2478/s13531-011-0021-x ◽

2011 ◽

Vol 1 (2) ◽

Cited By ~ 2

Author(s):

Jerzy Smolik

Keyword(s):

Coating Thickness ◽

Nitrided Layer ◽

Hot Forging ◽

Sem Analysis ◽

Internal Stresses ◽

Main Role ◽

Hybrid Layer ◽

Crn Coating ◽

Forging Process

AbstractThis article presents results which enabled the determination of the role of CrN coating and the influence of its thickness on the effectiveness of hybrid layer “nitrided layer / CrN coating” in the process of increasing the durability of forging dies. Dies coated with hybrid layers “nitrided layer / CrN coating” with various CrN coating thickness were — after different maintenance periods — subjected to metallographic testing, 3D shape testing and SEM analysis. Hardness distribution was also determined. The obtained results revealed that for all tested dies, independently from CrN coating thickness, the main mechanisms of their destruction was mechanical and thermal fatigue, and plastic deformation. It has been shown that the main role of CrN coating in the hybrid layer ”nitrided layer / PVD coating” is to counteract a high temperature influence the source of which is forging on die material. In order to do so the CrN coating should be characterized by a considerably lower thermal conductivity coefficient to steel and low hardness so that it can efficiently resist fatigue processes in the forging process. Based on testing conducted by means of the sin 2 φ method, it was revealed that internal stresses are vitally important for CrN coating for fatigue resistance of hybrid layer ”nitrided layer / CrN coating” during the forging process.

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The laboratory tests of hybrid layers combining hardfacing and nitriding dedicated to increase the durability of forging tools in hot forging processes

Welding Technology Review ◽

10.26628/wtr.v91i2.1020 ◽

2019 ◽

Vol 91 (2) ◽

Cited By ~ 2

Author(s):

Paweł Widomski ◽

Zbigniew Gronostajski ◽

Marcin Kaszuba ◽

Jagoda Kowalska ◽

Mariusz Pawełczyk

Keyword(s):

Surface Layer ◽

Chemical Composition ◽

Laboratory Tests ◽

Hot Forging ◽

Composition Analysis ◽

Wear Resistant ◽

Gas Nitriding ◽

Use Wear ◽

Different Types ◽

Hybrid Layers

In response to the growing need to use wear-resistant layers that increase durability of tools in forging pro-cesses, hybrid layers have been proposed that combine hardfacing with nitriding treatment. This article presents the results of laboratory tests of surface wear-resistant layers made with a new hybrid technology Gas-Shielded Metal Arc surfacing (hardfacing) with ZeroFlow gas nitriding. Specimens made with hardfacing or nitriding were prepared and examined. Analysis covered the thorough microstructure study, EDX chemical composition analysis and microhardness analysis. In experiment, 3 different types of nitrided layers were proposed for alpha, gamma prim and epsilon nitrides in the surface layer. The results of metallographic research in the surface layer was presented. The analysis of chemical composition in the particular overlay welds was performed to determine the content of alloying elements in the particular overlay welds. The susceptibility to nitriding of used weld materials as well as the ability to form particular types of nitrides on selected welded substrates was also tested.

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The application of a new, innovative, hybrid technology combining hardfacing and nitriding to increase the durability of forging tools

Archives of Civil and Mechanical Engineering ◽

10.1007/s43452-020-00122-1 ◽

2020 ◽

Vol 20 (4) ◽

Author(s):

Marcin Kaszuba

Keyword(s):

Wear Resistance ◽

Surface Layer ◽

Layer Structure ◽

Nitrided Layer ◽

New Technology ◽

Hot Forging ◽

Hybrid Technology ◽

Multiple Treatment ◽

Operational Tests ◽

The Impact

Abstract The article deals with the wear of forging tools used in hot forging processes. The research presented in the work includes analysis of tool life used in a selected industrial hot die forging process. Multiple treatment variants were used to increase wear resistance, including thermo-chemical treatment (nitriding), welding methods (surfacing) and an innovative new hybrid technology combining surfacing and nitriding. First of all, the research focused on determining the impact of the phase structure of the nitrided layers used and the surfacing layer on resistance to destructive factors occurring in the analyzed process. Next, hybrid treated tools combining surfacing and nitriding were also subjected to operational tests. Each of the tools analyzed in this work was operated until it was withdrawn due to excessive wear, and then subjected to comprehensive analysis. The tests of tools after operation included: surface scanning to determine the amount of wear of the analyzed tools after work, microhardness measurement, and microscopic tests. A detailed analysis of changes in the surface layer of tools in selected areas was made using a scanning microscope. The aim of the study was to assess the effectiveness of the hybrid surface treatment process used to increase the wear resistance of the surface layer of tools and thereby improve the durability of the forged tools analyzed. The obtained research results indicate a beneficial effect of using the new technology resulting in 300% increase in the durability of the analyzed tools. The effect of improving durability confirmed by obtained results arises from the use of hybrid layers, which are more resistant to abrasive wear and to cracking due to thermo-mechanical fatigue. Moreover, the study shows that nitriding may have a beneficial influence on improving the lifetime of forging tools, under the condition that the nitrided layer has an α diffusive layer structure, without a larger amount of γ’ and ε nitride precipitates.

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Dual phase titanium alloy hot forging process design: experiments and numerical modeling

Advances in Manufacturing ◽

10.1007/s40436-015-0127-0 ◽

2015 ◽

Vol 3 (4) ◽

pp. 269-281 ◽

Cited By ~ 5

Author(s):

A. Ducato ◽

G. Buffa ◽

L. Fratini ◽

R. Shivpuri

Keyword(s):

Numerical Modeling ◽

Titanium Alloy ◽

Process Design ◽

Hot Forging ◽

Dual Phase ◽

Forging Process ◽

Hot Forging Process ◽

Design Experiments

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Improvement of hot forging process of П-shaped forgings from VT14 and VT23 alloys

Blanking productions in mechanical engineering (press forging, foundry and other productions) ◽

10.36652/1684-1107-2020-18-11-502-507 ◽

2020 ◽

pp. 502-507

Author(s):

V.I. Galkin ◽

P.A. Golovkin ◽

S.A. Fesenko

Keyword(s):

Titanium Alloys ◽

Hot Forging ◽

Effect Of Temperature ◽

Temperature Deformation ◽

Structure And Properties ◽

Forging Process ◽

Deformation Parameters ◽

Hot Forging Process

The effect of temperature deformation parameters and the workpiece shape on the structure and properties of П-shaped die forgings made of the VT14 and VT23 titanium alloys.

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Case Study of the Effect of Precoating on the Decarburization of the Surface Layer of Forged Parts during the Hot Die Forging Process

Materials ◽

10.3390/ma14020422 ◽

2021 ◽

Vol 14 (2) ◽

pp. 422

Author(s):

Paweł Widomski ◽

Maciej Zwierzchowski ◽

Artur Barełkowski ◽

Mateusz Tympalski

Keyword(s):

Surface Layer ◽

Induction Heating ◽

Hot Forging ◽

Heating Process ◽

Forging Process ◽

Die Forging ◽

Forged Parts ◽

Third Stage ◽

Hot Die Forging

This paper aims to evaluate the effect of pre-coating of forged parts on decarburization in the die forging process. The studies consisted of three stages. In the first instance, different coatings were tested under laboratory conditions by heating steel samples to the temperature of 1200 °C for over five minutes to model the preheating conditions of the induction. Next, testing continued in a commercial forging stand where we tested the effects of different coatings on the rods decarburization during the induction heating process, usually performed before forging. Once completed testing, the measurements and observations of the decarbonized layer were made. The third stage involved analysis of the decarburization of the forged parts after forging. The forged parts were made using precoating of pre-forging elements; pieces cut off a metal rod. Based on tests results, the possibility of using this solution in the technique of industrial hot forging was evaluated. The results of laboratory tests have confirmed that lubrication of metal pieces is sufficient, as well as proved it to be effective in reducing decarburization of the surface layer. Research works conducted in an induction heater showed differences in decarburization depending on a substance and concentration of lubricants that were used. These differences become more apparent when observing the surface layer of the forged parts. Results indicate that decarburization may be reduced to a minimum when we use Bonderite product in a concentration of 66% and 50%. Another lubricant, Berulit 913, may also be used. However, due to burning graphite in high temperatures, reduction of decarburization goes only as far as half of the thickness of the decarbonized layer. Condursal has no significant effect; nevertheless, it protects over the induction heating stage.

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Factors Affecting the Wear Resistance of Forging Tools

Archives of Metallurgy and Materials ◽

10.1515/amm-2017-0240 ◽

2017 ◽

Vol 62 (3) ◽

pp. 1567-1576 ◽

Cited By ~ 2

Author(s):

M. Zwierzchowski

Keyword(s):

Surface Layer ◽

Working Conditions ◽

Laboratory Tests ◽

Effect Of Temperature ◽

Laboratory Studies ◽

Fem Modeling ◽

Factors Affecting ◽

Flat Surfaces ◽

Mechanical Fatigue ◽

Diffusion Layers

AbstractThe durability of forging tools is a function of many variables: tool heat treatment, surface quality, temperature, pressure, number of forgings, diffusion layers (nitriding) and many others. The objective of study was to analyze and compare the working conditions of forging tools. For the analysis of selected flat surfaces of tools. Analyzed forging dies subjected to normal use. Presented results of laboratory tests . The effect of temperature and time on the properties of the surface layer of forging tools. The results were compared with the literature data. This article shows the results of microhardness tests for forging dies which have forged the corresponding number of forgings. The results of laboratory studies on microhardness of hot working steel 1.2344 in the furnace at various temperatures and time are also presented. The working conditions of the forging tools are very complex. The most often described in the literature are: thermal fatigue, abrasive wear, mechanical fatigue and cracks. The article discusses the effects of increased temperature on the surface properties of forging tools. Forging dies were made of hot work tool steel 1.2344. FEM modeling of changes in the surface layer should take into account changes in tool hardness as a function of time (number of forgings).

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