Artykuł

Vol: 36 , Nr: , Art.: 4
Tytuł / Title:
The influence of laser re-melting on micro-structure and hardness of gas-nitrided steel
Wpływ parametrów laserowej obróbki cieplnej na mirostrukturę i mikrotwardość azotowanej gazowo stali
Autorzy / Authors:
PANFIL Dominika
WACH Piotr
KULKA Michał
MICHALSKI Jerzy
Institute of Materials Science and Engineering, Poznań University of Technology
Słowa kluczowe / key words:
gas nitriding, laser heat treatment, microstruture, hardness
azotowanie gazowe, laserowa obróbka cieplna, mikrostruktura, twardość
Streszczenie / Summary:

In this paper, modification of nitrided layer by laser re-melting was presented. The nitriding process has many advantageous properties. Controlled gas nitriding was carried out on 42CrMo4 steel. As a consequence of this process, e+gcompound zone and diffusion zone were produced at the surface. Next, the nitrided layer was laser re-melted using TRUMPF TLF 2600 Turbo CO2 laser. Laser tracks were arranged as single tracks with the use of various laser beam powers (P), ranging from 0.39 to 1.04 kW. The effects of laser beam power on the microstructure, dimensions of laser tracks and hardness profiles were analyzed. Laser treatment caused the decomposition of continuous compound zone at the surface and an increase in hardness of previously nitrided layer because of the appearance of martensite in re-melted and heat-affected zones

Vol: 36 , Nr: , Art.: 5
Tytuł / Title:
Microstructure, phase composition and corrosion resistance of Ni2O3 coatings produced using laser alloying method
Autorzy / Authors:
BARTKOWSKA Aneta
PRZESTACKI Damian
CHWALCZUK Tadeusz
Institute of Materials Science and Engineering, Poznań University of Technology
Słowa kluczowe / key words:
laser alloying; Ni2O3 oxide; microstructure; microhardness; corrosion resistance
Streszczenie / Summary:

The paper presents the studies' results of microstructure, microhardness, cohesion, phase composition and the corrosion resistance analysis of C45 steel after laser alloying with nickel oxide (Ni2O3). The aim of the laser alloying was to obtain the surface layer with new properties through covering C45 steel by precoat containing modifying compound, and then remelting this precoat using laser beam. As a result of this process the surface layer consisting of remelted zone and heat affected zone was obtained. In the remelted zone an increased amount of modifying elements was observed. It was also found that the surface layer formed during the laser alloying with Ni2O3 was characterized by good corrosion resistance. This property has changed depending on the thickness of the applied precoat. It was observed that the thickness increase of nickel oxides precoat improves corrosion resistance of produced coatings.

 

Vol: 36 , Nr: , Art.: 6
Tytuł / Title:
Determination of emissivity coefficient of heat-resistant super alloys and cemented carbide
Autorzy / Authors:
KIERUJ Piotr
PRZESTACKI Damian
CHWALCZUK Tadeusz
Institute of Machine Technology, Poznan University of Technology
Słowa kluczowe / key words:
nickel alloys, emissivity coefficient, tungsten carbides
Streszczenie / Summary:

This paper presents the analysis of emissivity engineering materials according to temperature. Experiment is concerned on difficult to machine materials, which may be turned with laser assisting. Cylindrical samples made of nickel-based alloys Inconel 625, Inconel 718, Waspaloy and tungsten-carbides based on cobalt matrix were analyzed. The samples’ temperature in contact method was compared to the temperature measured by non-contact pyrometers. Based on this relative, the value of the emissivity coefficient was adjusted to the right indication on pyrometers.

Vol: 36 , Nr: , Art.: 7
Tytuł / Title:
Laser-borided composite layer produced on austenitic 316l steel
Autorzy / Authors:
MIKOŁAJCZAK Daria
KULKA Michał
MAKUCH Natalia
DZIARSKI Piotr
Institute of Materials Science and Engineering, Poznań University of Technology
Słowa kluczowe / key words:
Laser boriding, austenitic steel, microstructure, hardness, wear resistance
Streszczenie / Summary:

Austenitic 316L steel is well-known for its good resistance to corrosion and oxidation. Therefore, this material is often used wherever corrosive media or high temperatures are to be expected. The main drawback of this material is very low hardness and low resistance to mechanical wear. In this study, the laser boriding was used in order to improve the wear behavior of this material. As a consequence, a composite surface layer was produced. The microstructure of laser-borided steel was characterized by only two zones: re-melted zone and base material. In the re-melted zone, a composite microstructure, consisting of hard ceramic phases (borides) and a soft austenitic matrix, was observed. A significant increase in hardness and wear resistance of such a layer was obtained.  

Vol: 36 , Nr: , Art.: 8
Tytuł / Title:
The use of IR thermography to show the mold and part temperature evolution in injection molding
Autorzy / Authors:
BULA Karol
RÓŻAŃSKI Leszek
MARCINIAK-PODSADNA Lidia
WRÓBEL Dawid
Institute of Materials Technology, Poznan University of Technology
Słowa kluczowe / key words:
IR thermography injection molding process polypropylene
Streszczenie / Summary:

This study concerns the application of infrared camera for injection molding analysis by measuring temperatures of both injection molded parts and injection mold cavities in a function of injection cycles. The mold with two cavities, differing in thickness (1 and 3 mm), and a cold direct runner was used. Isotactic polypropylene homopolymer was utilized to produce parts. Mold temperature was set at 22OC and controlled by a water chiller. Five measuring points were determined: SP1, SP2 (placed in the 3 mm cavity), SP3, SP4 (located in the 1 mm cavity) and SP5 around an injection molding gate. Our investigations showed that the highest temperature is localized around SP2 point and the lowest at SP4. Also, it was proved that even after 62 injection molding cycles, temperatures of cavities were not stable, revealing their further increase with each cycle.

Vol: 36 , Nr: , Art.: 9
Tytuł / Title:
Multi-scale curvature tensor analysis of machined surfaces
Autorzy / Authors:
BARTKOWIAK Tomasz
BROWN Christopher
Institute of Mechanical Technology, Poznań University of Technology
Słowa kluczowe / key words:
Curvature tensor, surface metrology, multi-scale geometric characterization, machining
Streszczenie / Summary:

This paper demonstrates the use of multi-scale curvature analysis, an areal new surface characterization technique for better understanding topographies, for analyzing surfaces created by conventional machining and grinding. Curvature, like slope and area, changes with scale of observation, or calculation, on irregular surfaces, therefore it can be used for multi-scale geometric analysis.  Curvatures on a surface should be indicative of   topographically dependent behavior of a surface and curvatures are, in turn, influenced by the processing and use of the surface. Curvatures have not been well characterized previously. Curvature has been used for calculations in contact mechanics and for the evaluation of cutting edges. In the current work two parts were machined and then one of them was ground. The surface topographies were measured with a scanning laser confocal microscope. Plots of curvatures as a function of position and scale are presented, and the means and standard deviations of principal curvatures are plotted as a function of scale. Statistical analyses show the relations between curvature and these two manufacturing processes at multiple scales.

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