In this work, the possibility of manufacturing complex-shaped components from a carbon-martensitic hardenable cold-work steel (1.2379; X153CrMoV12; D2) is investigated. For this purpose, cube-shaped ...samples with an edge length of 10 mm were produced using the fused-filament fabrication process, which were post-compacted after solvent debinding by supersolidus liquid-phase sintering. Using the knowledge of liquid phase volume content as a function of temperature, supersolidus liquid phase sintering experiments were performed. The microstructure formation process was characterized by electron microscopy and X-ray diffraction. The microstructure and hardness of the processed samples were compared in the heat-treated condition with the properties of the same steel 1.2379 (X153CrMoV12; D2) in the as-cast, deformed and heat-treated condition. The results demonstrate effective post-densificationc close to theoretical density of cold-work tool steel samples fabricated by fused-filamet fabrication using supersolidus liquid-phase sintering at 1280 °C. The defect-free microstructure in the heat-treated state is characterized by a martensitic matrix and eutectic Cr-rich M
C
and small amounts of V-rich MC carbides. The hardness of the annealed Supersolidus liquid phase sintering samples are 681 ± 5 HV10, which is above the level of the reference material 1.2379 (629 ± 7 HV10) in the as-cast, formed and heat-treated condition.
Abstract
During polymer extrusion there are a variety of situations in which the screwthread of the extrusion screw has an unlubricated metal-to-metal contact with the barrel wall. At the same time ...the screw coating is subjected to the highest loads. The combination of a secondary hardening cold work steel 1.2379 and a chromium nitride coating deposited by ARC-PVD, which is frequently used in polymer processing, is characterized and investigated. The characterization is done by metallographic examination, SEM and CLSM. The tests were performed on a pin-on-disk and a pin-roll test rig. Different roughness levels were tested on the pin-on-disk test, where massive differences in wear behavior were found. A hybrid surface structure is proposed to optimize the tribosystem. On the pin-on-disk test stand, rollers made of the same material pairing were tested. The test speed was varied to highlight differences and similarities between the tribological systems. A wear minimization of 50 % was achieved and the similarities between the tribological systems were highlighted. In addition, the investigations led to the development of a new model thesis which provides a reason for the development of stippling on the screw when processing polycarbonate.
•Localized dispersing of TiB2 in AISI D2 allows the formation of elevated textures.•The elevated surface features (implants) show hardness values up to 1800 HV1.•Hardness values result from dispersed ...particles and in-situ precipitated particles.•Implants show diameters from 150 µm up to 350 µm and heights up to 30 µm.
AISI D2 is one of the most applied cold-working tool steel for deep drawing operations, due to the materials good toughness and high wear resistance. However, since the lubricant-free deep drawing as well as the processing of high strength and ultra-high strength steel sheets remaining ongoing trends in the automotive industry, the tool surfaces need to be improved regarding their friction and wear behavior. For this purpose elevated micro textures can be applied. Since protruded micro features are predominantly affected by wear, a structuring process enabling the formation of suitable textures with high wear resistance is needed.
In this paper surface texturing at microscale was conducted by laser implantation. This technique allows the fabrication of highly wear resistant, separated and elevated features (implants) on steel surfaces via a discontinuous dispersing of ceramic particles by pulsed laser radiation. The aim of this study was to investigate the techniques potential for the creation of wear resistant elevated micro features on AISI D2 tool steel surfaces by the application of TiB2 particles. The laser parameters (pulse power and length) were varied and a comparative material analysis on AISI D2 laser remelted spots and TiB2 localized dispersed zones was examined. High-speed camera recordings allowed the description of the particle insertion mechanism from pre-coatings during laser processing. Mechanical properties were analyzed by (micro-) hardness measurements at top and cross sections. The microstructure was investigated by optical microscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The implants geometrical properties (diameter, height, depth) were investigated by white light interferometry and optical microscopy. The experiments reveal that a pulsed laser remelting of AISI D2 leads to a significant hardness drop due to high retained austenite (γR) contents. Contrary, a localized dispersing of TiB2 particles leads to defect free dome- or ring-shaped elevated features with hardness values up to 1800 HV1. The high hardness values result from the dispersed TiB2 particles and an in-situ precipitation of new hard particle phases, which lead to a reduction of the γR content within the matrix.
In today?s machining conditions, the goal is to produce the most suitable
quality with the lowest cost. In order to minimize the problems of mouth
spillage, especially those used in cutting molds, we ...have studied Sleipner
material as an alternative material and examined the machinability
parameters between DIN 1.2379 material used in the application. In this
study, with the aid of a force gauge, the forces generated on the material
during machining, the surface roughness values after machining with the help
of surface roughness device and the temperature values of the materials
during machining were measured with the temperature gauge. A total of twelve
experiments were carried out for each material at three different chip
depths at constant cutting speed and four different progressions for each
chip depth. These experiments have been understood from the results obtained
from the data that Sleipner material has shown a more stable structure and
better results than DIN 1.2379. Thus, the negative manufacturing conditions
that may occur during mold production and during mold operation are
minimized. In this case, it is necessary to take into consideration the
number of the parks produced in the mold and the frequency of mold usage in
the material selection of the cutting steel of the cutting molds.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
5.
Roughness prediction on laser polished surfaces Ukar, E.; Lamikiz, A.; Martínez, S. ...
Journal of materials processing technology,
June 2012, 2012-06-00, 20120601, Letnik:
212, Številka:
6
Journal Article
Recenzirano
► A method for the estimation of the topography of a laser polished process is presented. ► The model starts with the initial surface and the resultant topography is estimated. ► The model is based ...on the simulation of the thermal field generated by a laser beam. ► A critical filter frequency is defined and the initial profile frequencies are filtered. ► A thermal model is developed considering the solid-phase transformations. ► The model has been validated for laser polishing of DIN 1.2379 tool steel. ► The proposed method obtains coherent topographies agree with experimental data.
The paper presents a methodology to predict the surface topography on laser polished surfaces. The method is based on the thermal field prediction generated by the laser. The thermal field is obtained through the differential equation of heat transfer by conduction. The prediction of the resulting topography is based on the filtering of the spatial frequency spectrum of the initial topography which is obtained by FFT analysis. Once the temperature field is obtained, a critical frequency is calculated and a low-pass filter is applied to cut the frequencies higher than the critical one. The resulting surface is reconstructed using the remaining frequencies. The methodology has been tested on a DIN 1.2379 tool steel and the experimental validation shows a relatively good agreement between the predicted and measured values of mean roughness (Ra) and mean roughness depth (Rz), with errors lower than 15% in all the cases.
Metastable phases can be shifted to a different state by thermal loads on components. This leads to structural changes and precipitation. Within the scope of this investigation, a coating is applied ...to a solution annealed and a quenched and tempered substrate of the same chemical composition by means of a cold PVD process. The investigation is based on the process of polymer extrusion without additives. The substrate examined is 1.2379 tool steel. The substrate is used as a screw extruder material and is exposed to operating temperatures of up to 400 °C. A titanium layer is applied which is used in practice as an adhesion promoter and is in direct contact with the substrate. An annealing temperature above 500 °C results in special carbide hardening. These should show a worse layer adhesion than the metal bonds of the solution annealed sample. The aim is to investigate whether a difference is measurable or negligible. The loads during polymer extrusion are simulated by means of bending and pin-on-disk tests. The 3-point bending test simulates the mechanical load during extrusion. The pin-on-disk test simulates the friction between the extrusion screw flank and the extrusion cylinder. The substrate is characterized before and after sample preparation. Wear measurements are carried out using CLSM and SEM. The surface topography is recorded and then evaluated for comparison.
This paper deals with the tribological performance of forming tool steel 1.2379. Laser hardening and Laser surface texturing are proposed as processes to improve this tribological performance. ...Hardening influences the surface hardness and wear resistance. While considering the parameter and the specific material, the correlation between heating power and material property is first modelled using FEM of the heat transfer. Based on the modelling result, the realization is performed by nanosecond laser and analyzed by SEM and by comparing the micro –hardness comparison with a reference value.
Then textures are integrated into the hardened surface by picosecond laser ablation while focusing on its suitability for smooth dimples and on the examination by pin-on-disk tests for the effect of incorporating textures on the friction performance. Lower friction coefficients between tool and workpiece improve tool durability and product quality as well.
In this study the effect of electrode material was studied to avoid resulting residual stresses, the surface roughness and cracks resulted during Electrical Discharge Machining (EDM). Two types of ...EDM electrode materials were chosen, Dura graphite 11 and Poco graphite EDMC-3. Two grades of tool steels are chosen as test materials, DIN 1.2080 and DIN 1.2379. Different machining methods were chosen “rough, medium, and soft”, it was found that the Dura graphite 11 exhibits more surface cracks upon DIN 1.2379 less micro-cracks appeared on the surface than on DIN 1.2080 while the higher surface roughness appeared in DIN 1.2080 using Dura Graphite 11 electrode, also Residual stresses were studied upon the surface and it was found that POCO Graphite EDMC-3 electrode results higher residual stresses compared with Dura Graphite 11 electrode. Also Soft EDM machining exhibits higher residual stresses as a result of higher pulse on duration time.
Metastable phases can be shifted to a different state by thermal loads on components. This leads to structural changes and precipitation. Within the scope of this investigation, a coating is applied ...to a solution annealed and a quenched and tempered substrate of the same chemical composition by means of a cold PVD process. The investigation is based on the process of polymer extrusion without additives. The substrate examined is 1.2379 tool steel. The substrate is used as a screw extruder material and is exposed to operating temperatures of up to 400 °C. A titanium layer is applied which is used in practice as an adhesion promoter and is in direct contact with the substrate. An annealing temperature above 500 °C results in special carbide hardening. These should show a worse layer adhesion than the metal bonds of the solution annealed sample. The aim is to investigate whether a difference is measurable or negligible. The loads during polymer extrusion are simulated by means of bending and pin-on-disk tests. The 3-point bending test simulates the mechanical load during extrusion. The pin-on-disk test simulates the friction between the extrusion screw flank and the extrusion cylinder. The substrate is characterized before and after sample preparation. Wear measurements are carried out using CLSM and SEM. The surface topography is recorded and then evaluated for comparison.
Laser processing has become more relevant today due to its fast adaptation to the most critical technological tasks, its ability to provide processing in the most rarefied and aggressive mediums ...(vacuum conditions), its wide field of potential applications, and the green aspects related to the absence of industrial cutting chips and dust. With the development of 3D production, laser processing has received renewed interest associated with its ability to achieve pointed to high-precision powder melting or sintering. New technologies and equipment, which improve and modify optical laser parameters, contribute to better absorption of laser energy by metals or powder surfaces and allow for multiplying laser power that can positively influence the industrial spread of the laser in mass production and advance the existing manufacturing methods. The latest achievements in laser processing have become a relevant topic in the most authoritative scientific journals and conferences in the last half-century. Advances in laser processing have received multiple awards in the most prestigious competitions and exhibitions worldwide and at international scientific events. The Special Issue is devoted to the most recent achievements in the laser processing of various materials, such as cast irons, tool steels, high entropy alloys, hard-to-remelt materials, cement mortars, and post-processing and innovative manufacturing based on a laser.
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