Nitrogen hardening of creep-resistant G-NiCr28W alloy
Journal Title: Archiwum Odlewnictwa - Year 2010, Vol 10, Issue 3
Abstract
In the group of creep-resistant materials, most important are heat-resistant nickel-based alloys. The G-NiCr28W alloy subject to detailed examinations was observed to have two different austenite-like phases. In the interdendritic spaces of alloy matrix, the presence of another phase, also characterised by paramagnetic properties, was detected. Inside this interdendritic phase, local areas of a lamellar structure, composed of both of the above mentioned phases, were present. Nitrogen treatment was observed to raise the microhardness of both these phases. The presence of nitrogen made the regions of a lamellar structure disappear completely. Their place was occupied by precipitates dispersed in the matrix, and occasionally forming large clusters. It has been observed that cold work can harden the G-NiCr28W alloy to a very small degree only, in spite of the fact that hardness is increasing systematically with the increasing degree of cold work. The said alloy, when enriched with nitrogen added as an alloying element, is characterised by hardness higher than the hardness of its nitrogen-free counterpart. The value of hardness is increasing even more under the effect of low-degree cold work, although increasing further the degree of cold work seems to have no effect on hardness increase. The problem faced in nickel-based materials is the possibility of making defect-free castings from alloys with high nitrogen content. Alloys investigated in the present study were remelted, cast and subject to solidification under high nitrogen pressure in the furnace chamber. However, melting carried out under these conditions could not prevent the occurrence of non-metallic inclusions which, while being unable to pass to a riser, formed local clusters or even thin films, resulting in numerous microcracks or discontinuities encompassing large regions of the casting. This problem seems to be of major concern and is the first one to require prompt solution in the currently executed large research project.
Authors and Affiliations
Z. Pirowski, J. Wodnicki, A. Gwiżdż
Keywords
Related Articles
- EP ID EP72136
- DOI -
- Views 117
- Downloads 0
Influence of the technology of melting and inoculation preliminary alloy AlBe5 on change of concentration of Al and microstructure of the bronze CuAl10Ni5Fe4
Examining was the aim of the work: influence of the permanent temperature 1300°C ± 15°C and changing time of isothermal holding in the range 0÷50 minutes on the melting loss of aluminum in the bronze CuAl10Ni5Fe4; the qu...
Acquisition of technology knowledge from online information sources
The article discusses problems related with the search of information from open sources, particularly on the Internet. Specific area of concern is searching for technical knowledge in the area of metalcasting. The result...
Quality management as a tool forming foundry competitive capacity in the process of market globalisation
This paper presents the analysis and identification of the key factors influencing the competitiveness of the foundry in the process of market globalisation. The main attention is paid to the quality management as an imp...
The structure of connection of the AlSi5 – HS6-5-2 compound casting obtained by alphinising
The paper presents results of the analysis of the alphinising coat connection structure of the AlSi5 silumin – high speed steel HS6-5-2 compound casting. The alphinising coat was made in the AlSi5 silumin bath with tempe...
Safety management system of subcontractors’ works in foundry companies
Most companies use the services of subcontractors, either in their core business, or to support the work – e.g. maintenance. This poses the need for effective and systematic monitoring of the work of subcontractors, espe...