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Selective Laser Melting of H13-TiB2 metal matrix composites - the role of volumetric energy density

Grzesiak Dariusz, AlMangour Bandar, Figiel Paweł, Fryska Sebastian

Journal of Machine Construction and Maintenance - Problemy Eksploatacji

2019

no. 1

47--52

The paper presents an analysis of the impact of the volumetric energy density delivered during the Selective Laser Melting (SLM) of a mixture of H13 tool steel powder and microcrystalline TiB2 , on the properties of the obtained metallic matrix composite. The results of measurements of density and hardness as well as microscopic analysis of six variants of the obtained composite, differing in the value of energy density provided by the laser beam and the number of passes of this beam on each fused layer, are presented. The results show that, in the case of a metallic matrix composite, the increase in the volumetric energy density supplied during the SLM process can lead to the deterioration of the material properties.

Artykuł przedstawia analizę wpływu objętościowej gęstości energii dostarczanej podczas selektywnego stapiania laserowego mieszaniny proszku stali H13 oraz mikrokrystalicznego TiB2 na właściwości uzyskanego w ten sposób kompozytu w osnowie metalicznej. Przedstawiono wyniki pomiarów gęstości i twardości oraz analizę mikroskopową sześciu wariantów otrzymanego kompozytu, różniących się wartością gęstości energii dostarczonej przez wiązkę lasera i ilością przejść tej wiązki na każdej stapianej warstwie. Wyniki pokazują, że w przypadku kompozytu w osnowie metalicznej zwiększanie objętościowej gęstości energii dostarczanej przy stapianiu może prowadzić do pogorszenia właściwości materiału.

Dual Speed Laser Remelting for High Densification in H13 Tool Steel Metal 3D Printing

Jung Im Doo, Choe Jungho, Yun Jaecheol, Yang Sangsun, Yang Dong-Yeol, Kim Yong-Jin, Yu Ji-Hun

Archives of Metallurgy and Materials

2019

Vol. 64, iss. 2

571--578

The densification behavior of H13 tool steel powder by dual speed laser scanning strategy have been characterized for selective laser melting process, one of powder bed fusion based metal 3d printing. Under limited given laser power, the laser re-melting increases the relative density and hardness of H13 tool steel with closing pores. The single melt-pool analysis shows that the pores are located on top area of melt pool when the scanning speed is over 400 mm/s while the low scanning speed of 200 mm/s generates pores beneath the melt pool in the form of keyhole mode with the high energy input from the laser. With the second laser scanning, the pores on top area of melt pools are efficiently closed with proper dual combination of scan speed. However pores located beneath the melt pools could not be removed by second laser scanning. When each layer of 3d printing are re-melted, the relative density and hardness are improved for most dual combination of scanning. Among the scan speed combination, the 600 mm/s by 400 mm/s leads to the highest relative density, 99.94% with hardness of 53.5 HRC. This densification characterization with H13 tool steel laser re-melting can be efficiently applied for tool steel component manufacturing via metal 3d printing.

Heat treatment of a hot-work die steel

Qamar S. Z., Sheikh A. K., Arif A. F. M., Pervez T., Siddiqui R. A.

Archives of Materials Science and Engineering

2007

Vol. 28, nr 8

503-507

Purpose: This paper reports results of in-house experimentation and an exhaustive literature search on heat treatment of H13 tool steel. Heat treatment strategy practiced by the industry is described in detail. Effect of various types of heat treatment on fracture toughness and hardness is also analyzed. Design/methodology/approach: Because of its versatility and wide applications, aluminum has been dubbed as the metal of the millennium. Commercial extrusion of aluminum alloys is a cyclic hot-working process. The magnitude of the thermal and mechanical stresses generated in the die and relevant tooling is therefore a major factor in extrusion. The die and mandrel (used for hollow profiles) are the most important tools subject to wear and are, at the same time, the most highly stressed tools in extrusion. For reliability and durability of an extrusion die, the load carrying capacity of the tool steel, its high-temperature fatigue properties, and its wear resistance become critically important. To withstand large stresses, the steel should have high strength and toughness, and to resist wear it should have high hardness and surface integrity. This combination of high toughness and high hardness is usually achieved through specific heat treatment and surface hardening sequences. Findings: Toughness (expressed in terms of plane-strain fracture toughness KIC or Charpy impact energy CVN) and hardness (HRC) of H13 steel vary in a nonlinear manner against tempering temperature. Toughness shows a decreasing-increasing trend, while hardness exhibits an opposite increasing-decreasing pattern with increasing tempering temperature. Research limitations/implications: Optimum heat treatment strategy for commercial aluminum estrusion dies (H13 steel) appears to be tempering in the 525-550 °C temperature range, to get the best combination of high toughness and high hardness Originality/value: Experimental data from closely monitored heat treatment and mechanical testing has been added to the available published data. Careful and judicious extrapolatiopn-intrapolatioon has also been carried out to complete the data matrices. Analysis of the resulting variation pattersns provideds a good scientific foundation for devising an optimal heat treatment strategy.