Wyniki wyszukiwania - BazTech

1

Oxide Formation In Metal Injection Molding Of 316L Stainless Steel

Jang J. M., Lee W., Ko S.-H., Han C., Choi H.

Archives of Metallurgy and Materials

|

2015

|

Vol. 60, iss. 2B

1281--1285

EN

The effects of sintering condition and powder size on the microstructure of MIMed parts were investigated using water-atomized 316L stainless steel powder. The 316L stainless steel feedstock was injected into micro mold with micro features of various shapes and dimensions. The green parts were debound and pre-sintered at 800°C in hydrogen atmosphere and then sintered at 1300°C and 1350°C in argon atmosphere of 5torr and 760torr, respectively. The oxide particles were formed and distributed homogeneously inside the sample except for the outermost region regardless of sintering condition and powder size. The width of layer without oxide particles are increased with decrease of sintering atmosphere pressure and powder size. The fine oxides act as the obstacle on grain growth and the high sintering temperature causes severe grain growth in micro features due to larger amount of heat gain than that in macro ones.

2

Powder pneumatic injection as a tool for wastes utilization

Jezierski J., Janerka K.

Archives of Materials Science and Engineering

|

2009

|

Vol. 36, nr 2

118-124

EN

Purpose: Metallurgical process generates many solid, gaseous and liquid wastes. Nowadays when environmental protection is one of the most important problems and when pollution limits are very tight as well, problem of the metallurgical wastes is a strategic one. Design/methodology/approach: In present days the metallurgical and foundry plant have to utilize their own wastes, especially these which are the most dangerous and toxic or have to render harm of its and transfer to another industry branch for further utilization. Nowadays the issue of wastes management has the place both in industrial practice and scientific field too. The presented work is a result of such an approach, where a cooperation between scientific and industrial partners gives good economical and ecological results. Findings: One of the very efficient method of utilization of furnace dusts from any melting furnace or the finest fractions of charging materials is pneumatic powder injection directly into molten metal bath.The method is pretty easy and cost effective in various conditions and its flexibility allows to implement it in almost every foundry or metallurgical plant. Research limitations/implications: Further experiments should be carried out to solve some additional problems appearing during powder injection processes to make them more efficient in various technological conditions. Practical implications: Nowadays in Poland operate more than ten industrial stands for powdered carburizers injection, installation of furnace dust injection back to the melting furnace or pneumatic inoculation of alloys (mostly in cast iron foundries). Originality/value: The paper presents a few modern solutions for recycling and utilization of furnace dusts (in cupolas and EAF’s) and pneumatic carburization with use of powdered carburizers which are very often in form of grinded graphite electrodes wastes. All of the mentioned results and method had been developed in Department of Foundry and some of the designs had been previously patented.

3

Carburization process rate in production of synthetic cast iron

Janerka K., Bartocha D., Szajnar J.

Archives of Materials Science and Engineering

|

2009

|

Vol. 36, nr 1

55-61

EN

Purpose: The main goal of the paper was to determine the possibility of synthetic cast iron production on base of steel and process scraps as well as the carburization effectiveness, realized with three methods - fully described in main text. Design/methodology/approach: Each of described methods has undoubted advantages but also has a number of disadvantages. In foundry engineering practice the most essential parameters of this process are to obtain as high as possible degree of carbon assimilation from carburizer, in as short as possible time, with high process repeatability. Findings: Decrease of share or elimination the whole amount of the pig iron from charge materials causes reduction cost of gray or ductile cast irons melt. Now the very important issue is working out the effective and, repeatable in industrial conditions, carburization method. Research limitations/implications: Obtained results of experiment on carburization in electric arc furnaces allow to apply pneumatic carburization method in a dozen of domestic foundries. Described in main text researches concern inductive furnaces, which are the wideness group of melting furnaces applied in foundry engineering. Basis on results of these research authors have affirmed that the method characterized with the most carburization effectiveness is the pneumatic injection of carburizer in stream of carrying gas. Practical implications: Industrial application of pneumatic carburization method unfortunately required significant financial outlay on devices purchase. Considerably cheaper method, but characterized with less repeatability is an addition of carburizer to solid charge. Originality/value: Realized experiment is a part of statutory researches, which are carried out in Foundry Department of Institute of Engineering Materials and Biomaterials and supply us with not only utilitarian value - worked out effective method for carburization in industrial conditions, but also experience value - rate change of carbon content increase in function of time for changeable parameters of liquid metal.

4

Character of diphase stream force in powder injection technique

Jezierski J., Szajnar J.

Journal of Achievements in Materials and Manufacturing Engineering

|

2007

|

Vol. 20, nr 1-2

455-458

EN

Purpose: The method of pneumatic injection of powdered reagents into liquid alloys in some moment of melting process is known since many years. Mostly it is carrying out with use of submerged lance but in some cases that technique is difficult or impossible at all to use. This is the reason for making investigations in the filed of powders injection with non-submerged lance. Design/methodology/approach: The main experimental method was measurement and recording of time-changing diphase stream force value with use of dedicated laboratory stand. The recorded data made possible to show character of force in form of graphs and calulation of stream parameters. The last step was formulating of statistical equations joining all important parameters of the process. Findings: In the course of the work was found a diphase stream force character (especially interesting are start and end point of injection). The influence of main pneumatic parameters on the force value was analyzed too. Research limitations/implications: The future experiments will be conducted with use to Fluent 6.2 program for checking the results in computer simulations. The limitation is number of values being analyzed in experimental plan. Practical implications: The invented lance can be used for powders pneumatic injection but only for small its quantities (e.g. microalloying) because non-immersed lance should be used with low stream concentration. The usage of that lance can increase liquid alloy heat losses (not introducing carrier gas into liquid) and lance consumption (non-immersed in liquid bath). Originality/value: The problem of stream force in powder injection process is in Poland only analyzed by Department of Foundry and nobody (in author's opinion) was analyzed it with connection in powder injection. Originality of the researches is a computer recording and analyzing of the diphase stream force. The results should interest every who wants to learn more about pneumatic powder injection.

5

The carburization process rates in synthetic cast iron production

Janerka K., Bartocha D., Szajnar J.

Journal of Achievements in Materials and Manufacturing Engineering

|

2006

|

Vol. 18, nr 1-2

379--382

EN

Purpose: The aim of presented researches was determination of possibility of synthetic cast iron production on base of steel and process scrap as well as determination of carburization effectiveness, realized with three methods: addition of carburizer to charge in solid, addition of carburizer on surface of liquid metal, pneumatic injection of carburizer in stream of carrying gas to liquid metal. Design/methodology/approach: Each of these methods have a undoubted advantages but also have a numer of disadvantages. In foundry engineering practice the most essential parameters of this process are to obtain as high as possible degree of carbon assimilation from carburizer, in as short as possible time, with high proces repeatability. Findings: Decrease of share or elimination of the pig iron from charge materials causes significant reduction of cast iron melt costs. Working out the effective and repeatable crburization method is a very important issue. Research limitations/implications: The result of carburization in arc electric furnaces experiments carried out by the authors of this paper made possibility on application method of pneumatic carburization in a dozen of domestic foundries. Presented below researches concern inductive furnaces, which are a wide group of melting furnaces applied in foundry engineering. Basis on these researches affirmed that the most effectiveness carburization method is the pneumatic injection of carburizer in stream of carrying gas. Practical implications: This method required significant financial outlay on devices purchase. Considerably cheaper method, but less repeatable is a addition of carburizer to solid charge. Originality/value: Realized experiments are a part of statutory researches and have not only utilitarian value (worked out effective method for carburization in industrial conditions), but also experience (rate change of carbon content increase in function of time for changeable parameters of liquid metal.

6

Wdmuchiwanie proszków do ciekłych stopów metali jako narzędzie poprawy ich jakości

Jezierski J., Janerka K., Szajnar J.

Archiwum Odlewnictwa

|

2006

|

R. 6, nr 18/1

535--540

PL

W pracy przedstawione zostały korzyści wynikające z zastosowania metody pneumatycznego wprowadzania sproszkowanych reagentów do ciekłych stopów żelaza w aspekcie poprawy ich jakości. Najszersze zastosowanie wdmuchiwania proszków w odlewnictwie wiąże się z nawęglaniem (dowęglaniem) ciekłego żeliwa a także wprowadzaniem niewielkich ilości dodatków stopowych i analiza tych właśnie zagadnień jest głównym tematem niniejszej pracy. Ponadto przedstawiono propozycję modyfikacji stanowiska do wdmuchiwania proszków, zapewniającą utrzymanie wysokich wartości wskaźników technologicznych (efektywności) przy jednoczesnej poprawie jakości ciekłego stopu w czasie procesu wdmuchiwania.

EN

In the paper has been presented the benefits of pneumatic reagents introduction into liquid alloys in aspect of its quality improving. The widest use of powder injection technique in foundry is the cast iron recarburization and small quantities of alloy additions introduction and those problems are the main subject of this work. Moreover, there were presented a modification of injection stand which give the same high technological parameters (efficiency) and better quality of alloy through all the injection process.