Effect of Laser Beam Alloying Strategies on the Metallurgical and Mechanical Properties of Hot Forming Tool Steels

Hofmann, Konstantin; Neubauer, Franziska; Holzer, Matthias; Mann, Vincent; Hugger, Florian; Roth, Stephan; Schmidt, Michael

doi:10.1016/j.phpro.2016.08.023

Cited by 3 publications

(6 citation statements)

References 7 publications

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“…Despite the fact, that the rectangular cross sections may be added easier to a larger volume with constant depth than circle segments, there may be an unwanted heat treatment of the previous trace, when scanning along parallel traces. This problem was solved taking advantage from FEM-simulation [90]. The simulation helped to determine the processing parameters (line energy and process distance), where no influence of a trace on the previous trace is given.…”

Section: Changing Materials Propertiesmentioning

confidence: 99%

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Advances in macro-scale laser processing

Schmidt

Zäh

et al. 2018

CIRP Annals

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Section: Changing Materials Propertiesmentioning

confidence: 99%

“…This was possible due to the fact, that the critical transition temperature was as low as 100°C. As long as the temperature of one area does not drop below this temperature, reheating by the heat from the following track does not affect the hardness [90].…”

Section: Changing Materials Propertiesmentioning

confidence: 99%

Advances in macro-scale laser processing

Schmidt

Zäh

et al. 2018

CIRP Annals

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“…The tool surfaces are modified by laser alloying [11] or coating. In this regard, WP7V is primarily used for the laser alloying process, as it is already high-alloyed especially with chromium.…”

Section: Specimensmentioning

confidence: 99%

“…As main alloying elements Ti, Mo, Cr and C were selected since they are transition metals with a lower density of moving electrons than metals and consequently the tendency to metallic adhesion can be reduced [12]. For the experiments an Yb:YAG fiber laser was used with a nominal output power of 1 kW and a wavelength of 1070 nm [11]. The alloying process was performed at 500 W, while the clamped specimen on a sledge was moved with an axis speed of 6 mm/s under the laser beam [11].…”

Section: Specimensmentioning

confidence: 99%

“…For the experiments an Yb:YAG fiber laser was used with a nominal output power of 1 kW and a wavelength of 1070 nm [11]. The alloying process was performed at 500 W, while the clamped specimen on a sledge was moved with an axis speed of 6 mm/s under the laser beam [11]. The wire was guided into the process using a feeding unit FD 100 LS-WB by DINSE with a constant speed of 0.2 m/min.…”

Section: Specimensmentioning

confidence: 99%

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Tribological and Thermal Investigation of Modified Hot Stamping Tools

Neubauer¹,

Merklein²

2019

Tribol. Ind.

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Direct hot stamping is an established manufacturing process to produce safety-relevant car body components, while t-he hot blank is formed and quenched simultaneously in a water cooled press. In order to protect the semi-finished parts against oxidation the surfaces are coated with aluminum silicon. As a side effect this coating system leads to adhesive wear on the tool surface, which reduces the tool life. Due to the high temperatures it is not possible to use lubricants as wear protection. For this reason a suitable surface modification for hot stamping tools is required to increase the wear resistance. In the scope of this study the tribological behavior of different modificatiosn is investigated. The main purpose of these wear protective layers is to decrease the adhesive wear on the tool surface. The wear characterization is carried out with a modified pin-on-disc test. During the experiments the pin is guided over the blank with a robot system. In addition, the contact area is cooled after each wear track to simulate the thermal alternating stresses of the hot stamping process. For the evaluation of the wear behavior a new developed analysis method is used, which enables the calculation of the adhesive and abrasive wear volume.

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Increasing the Adhesive Wear Resistance of Hot Stamping Tools by Modifying the Surfaces

Neubauer

Reil

Hofmann

et al. 2018

KEM

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Over the last few years lightweight construction became increasingly important in modern cars. Motivated by reducing greenhouse gas emission the car industry is currently working on different approaches to decrease the weight of structural body parts. In this regard, a reduced sheet thickness of these components and therefore a reduced overall weight can be achieved by using high-strength steels. Hot stamping has been established as a suitable manufacturing process for these steel grades, in which a hot austenitic blank is formed and quenched simultaneously. The high strength of the formed parts is realized by the phase transformation of an austenitic to a martensitic structure during hot stamping. Due to the alternating thermo-mechanical loads, which occur during forming and quenching, the hot stamping tools are highly stressed. In addition, when the blank slides over the surface of its counterpart, a substantial adhesive wear occurs, which is the predominant wear mechanism in hot stamping. The aim of this study is, to increase the wear resistance of the tools by modifying the surface. In this context, the chemical affinity between the interacting components need to be reduced in order to decrease the adhesive wear on the hot stamping tool, which is possible by alloying the base material. For this reason, the wear development is investigated for samples alloyed with different materials with a modified pin-on-disc test. This experimental setup enables a continuous contact of the tool with the blank and thermal alternating stress of the pin. The contact area is investigated with a laser-scanning microscope to qualify the tool surface before and after the experiments by measuring the tool topographies. The results of an unalloyed and alloyed tool will be compared with each other to evaluate the wear behavior. In order to quantify the amount of wear the wear volume will be calculated with an algorithm of the software WinSam. The experiments will be carried out under process like conditions to ensure transferability to the real hot forming process.

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Effect of Laser Beam Alloying Strategies on the Metallurgical and Mechanical Properties of Hot Forming Tool Steels

Cited by 3 publications

References 7 publications

Advances in macro-scale laser processing

Advances in macro-scale laser processing

Tribological and Thermal Investigation of Modified Hot Stamping Tools

Increasing the Adhesive Wear Resistance of Hot Stamping Tools by Modifying the Surfaces

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