Failures of AISI H21 die in copper hot extrusion

Schwartz, M.; Ciocoiu, Robert; Gheorghe, D.; Ciucă, Ion

doi:10.1179/1878641313y.0000000001

Cited by 7 publications

(9 citation statements)

References 5 publications

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“…Research performed on failed steel extrusion dies showed, in our case, the failure by softening caused by carbide coalescence and depletion of the matrix of the reinforcing element; the carbides [3].…”

Section: Introductionmentioning

confidence: 61%

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Preliminary research for using Rene 41 in confectioning extrusion dies

Schwartz

Ciocoiu

Gheorghe

et al. 2015

WIT Transactions on Engineering Sciences

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The dies used for copper/brass hot extrusion made of tool steels failed after a small number of runs. The die must be either refurbished (reconditioned) either discarded or replaced by a new die. These results are not satisfactory for a good production, so we took into account a new alloy to use for confectioning the dies. Before the first die was readily made, an experiment was performed to justify the migration to this new alloy.Heating cycles are performed to observe microstructure evolution in Rene 41. These heating cycles mimic the usage conditions of the die in service, except the stresses during extrusion. The alloy at specific number of cycles is analyzed by optic and electron microscopy (SEM), X-ray diffraction analysis (XRD), Vickers microhardness investigations and dilatometric tests.Minor changes occurred in the microstructure: M23C6 carbides appeared at grain boundary and depleted adjacent regions in alloying elements.

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Section: Introductionmentioning

confidence: 61%

“…Simulating only the temperature effects on the material the microstructure was investigated and the decision was taken by comparison with usual tool steel used in the factory [3]. The thermal cycles produced an effect similar to heat treatment.…”

Section: Discussionmentioning

confidence: 99%

Preliminary research for using Rene 41 in confectioning extrusion dies

Schwartz

Ciocoiu

Gheorghe

et al. 2015

WIT Transactions on Engineering Sciences

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“…For AISI H21 steel the expansion curve analysis revealed the transformation temperature at 796 o C and 831 o C with no particular aspect-the curve was presented in [3].…”

Section: Resultsmentioning

confidence: 99%

“…Previous research allowed us to identify the steel die failure mechanism for our particular application: copper hot extrusion die softening caused by carbide coalescence and matrix depletion of reinforcing elements [3].…”

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confidence: 99%

A Comparative Microstructure Evolution of AISI H21 and Inconel 718 in Cyclic Heating

Gheorghe¹,

Schwartz²,

Ciucă³

et al. 2018

Mat.Plast.

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The AISI H21 steel used for dies in copper hot extrusion softened only after several runs. To improve production parameters a new material was necessary for the die, and, as a first choice, Inconel 718 was preferred. Prior to adopting this material for new extrusion dies an experimental program with temperature exposure cycles was performed so as to study microstructure evolution within AISI H21 and Inconel 718. The samples were studied by optic and scanning electron microscopy (SEM) and were also submitted to X-ray diffraction (XRD) and microhardness tests. The results showed carbide coalescence, which led to softening, followed by a re-precipitation in the steel, while, in Inconel 718, the precipitation (in small amounts) of delta (ä) phase was observed.Using these results and combining them with practical experience with steel, we could predict that the Inconel 718 die performance is such that at least a double quantity of copper could be extruded per die.

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“…Typically billet temperatures of above 600°C and up to 1050°C are applied, which exposes the extrusion dies to high thermo-mechanical stress [1]. As a result, plastic deformation, chipping or cracking may occur, necessitating recalibration or replacement of the die [2]. Conventional hot-work tool steels are highly prone to such wear and failure, as their soft annealing resistance is far exceeded at these temperatures.…”

Section: Intr Introduction Oductionmentioning

confidence: 99%

Numerical analysis of plastic die deformation during high temperature copper extrusion

Lechner¹,

Nitschke²,

Müller³

2021

Esaform 2021

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In copper extrusion, billet temperatures of 600°C or more are very common and the dies are therefore exposed to high thermo-mechanical stress. This causes deflection and wear of the dies and thus reduced quality of the extruded profile. In the present study, die deflection and residual deformation after several extrusion cycles was investigated by means of extrusion trials and numerical analyses. Material models of four tool materials (hot-work tool steels 1.2367 and CS1, nickel-based alloy 718, cobalt-based alloy Stellite 1) and the copper alloy CW024A were provided by hot compression tests. Extrusion trials were carried out applying four different dies, each made of another tool material. Using the FEM based software DEFORM 2D, the extrusion trials were modeled and decoupled die stress analyses were performed, which simulated three consecutive load cycles. The focus of the data interpretation was in die deflection in proximity of the die land due to the thermo-mechanical load and residual plastic deformation after relief of the mechanical load. Larger values of deflection close to the die land were observed for the hot-work tool steels, while the deflection of nickel- and cobalt-based alloys was negligibly small. Also, remarkable plastic deformation was only determined for the hot-work tool steels, with increasing values for every simulated load cycle. This analysis characterizes the performance limits of hot-work tool steels and the benefits of nickel- and cobalt-based alloys regarding contour accuracy during high temperature copper extrusion.

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Failures of AISI H21 die in copper hot extrusion

Cited by 7 publications

References 5 publications

Preliminary research for using Rene 41 in confectioning extrusion dies

Preliminary research for using Rene 41 in confectioning extrusion dies

A Comparative Microstructure Evolution of AISI H21 and Inconel 718 in Cyclic Heating

Numerical analysis of plastic die deformation during high temperature copper extrusion

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