PlaSSteel Project
Stainless steels have a vast application in modern industries. Because of their ability to resist different types of corrosion, stainless steels are used in the chemical industry, oil industry, food industry and paper manufacturing, the pharmaceutical and biomedical sectors and many more.
Though stainless steels have excellent corrosive characteristics, they fall down on mechanical properties - their ductility is good but the surface hardness is not so remarkable. While holding in corrosive environments where other steels won’t do the job, the parts from stainless steels fail due to different types of wear and due to fatigue, which leads to failure, needed services and repairs and increase in the overall costs on the product.
The PlaSSteel project is developed by Ionitech Ltd. to find a solution in this area. The idea of the project is to develop a heat treatment that will increase the surface hardness, leading to higher wear resistance of the parts, an increase of their fatigue life, while in the same time keeping their corrosion resistance properties.
The process is done in Ionitech’s plasma nitriding furnace, and it is a low-temperature diffusion process in plasma that adds carbon and nitrogen into the lattice structure of the material. This leads to about 3-4 times of enhancement of the surface hardness, increase in the wear resistance; enhanced fatigue life, while in the same time eliminating the susceptibility of the stainless steel to pitting corrosion and keeping the ductility of the steel.
Based on its more than 40 years of experience, Ionitech Ltd. has developed a Plasma Nitriding/Nitrocarburising furnace achieving excellent temperature uniformity throughout the whole working area. It also eliminates the possibility for the “hollow-cathode” effect (local overheating of the parts). This local overheating might lead to temperatures above the needed low temperatures for the PlaSSteel process that will in turn lead to precipitation of chromium carbides and nitrides on the grain boundaries of the steel, these places of the part will have a higher surface hardness, but also will be susceptible to intergranular corrosion. This negative effect is prevented by the excellent plasma and temperature control of Ionitech’s furnaces.
Project development
Several types of stainless steels were processed and tested – ferritic, martensitic, austenitic and duplex. This report will be focused on the processing and evaluating of the results of the austenitic stainless steel - SS 316.
For a starting point in the development of the PlaSSteel technology, Ionitech technologists’ vast experience in plasma nitriding was used. Serious research was done on stainless steels, and on different types of corrosion. Ionitech worked closely with BAS (Bulgarian Academy of Science), the Technical University of Ruse, our partners from Macedonia – the company Center for Plasma Technology ‘Plasma’, and our partners from the USA – the company IBC Coatings, and the Bulgarian company Nikom 65 for the tests that couldn’t be performed in-house.
Research, results and evaluation
Though stainless steels have excellent corrosive characteristics, they fall down on mechanical properties - their ductility is good but the surface hardness is not so remarkable. While holding in corrosive environments where other steels won’t do the job, the parts from stainless steels fail due to different types of wear and due to fatigue, which leads to failure, needed services and repairs and increase in the overall costs on the product.
The PlaSSteel project is developed by Ionitech Ltd. to find a solution in this area. The idea of the project is to develop a heat treatment that will increase the surface hardness, leading to higher wear resistance of the parts, an increase of their fatigue life, while in the same time keeping their corrosion resistance properties.
The process is done in Ionitech’s plasma nitriding furnace, and it is a low-temperature diffusion process in plasma that adds carbon and nitrogen into the lattice structure of the material. This leads to about 3-4 times of enhancement of the surface hardness, increase in the wear resistance; enhanced fatigue life, while in the same time eliminating the susceptibility of the stainless steel to pitting corrosion and keeping the ductility of the steel.
Based on its more than 40 years of experience, Ionitech Ltd. has developed a Plasma Nitriding/Nitrocarburising furnace achieving excellent temperature uniformity throughout the whole working area. It also eliminates the possibility for the “hollow-cathode” effect (local overheating of the parts). This local overheating might lead to temperatures above the needed low temperatures for the PlaSSteel process that will in turn lead to precipitation of chromium carbides and nitrides on the grain boundaries of the steel, these places of the part will have a higher surface hardness, but also will be susceptible to intergranular corrosion. This negative effect is prevented by the excellent plasma and temperature control of Ionitech’s furnaces.
Project development
Several types of stainless steels were processed and tested – ferritic, martensitic, austenitic and duplex. This report will be focused on the processing and evaluating of the results of the austenitic stainless steel - SS 316.
For a starting point in the development of the PlaSSteel technology, Ionitech technologists’ vast experience in plasma nitriding was used. Serious research was done on stainless steels, and on different types of corrosion. Ionitech worked closely with BAS (Bulgarian Academy of Science), the Technical University of Ruse, our partners from Macedonia – the company Center for Plasma Technology ‘Plasma’, and our partners from the USA – the company IBC Coatings, and the Bulgarian company Nikom 65 for the tests that couldn’t be performed in-house.
Research, results and evaluation
Ionitech’s PlaSSteel technology is based on the incorporation of nitrogen and carbon into the stainless steel, through diffusion, which leads to deformation of the lattice structure and creates compressive stresses that enhance the localized hardness. This results in high surface hardness and wear-resistance properties.
Based on all of the research and tests, Ionitech has prepared a technology for a low temperature nitriding of stainless steels that:
- Increases 3 - 4 times the surface hardness, which results in an increase of the wear resistance of the steel.
- No distortion of the parts – the process temperature is low, so that eliminates distortions, and there is no need for post-process machining.
- No chromium nitride or carbide precipitations at grain boundaries, which eliminates the possibility of intergranular corrosion.
- After electrochemical pitting corrosion test – there was no pitting corrosion found, while the untreated sample suffered from pitting corrosion.
The achieved results are remarkable the further work that continues with actual clients will help us to further improve our technology and results.
Ionitech Ltd.'s ‘Plasma Nitriding and Nitrocarburising for high wear resistance and high corrosion stability Stainless Steel — PlaSSteel’ project that will be Co-funded by the Horizon 2020 Framework Programme of the European Union.
Based on all of the research and tests, Ionitech has prepared a technology for a low temperature nitriding of stainless steels that:
- Increases 3 - 4 times the surface hardness, which results in an increase of the wear resistance of the steel.
- No distortion of the parts – the process temperature is low, so that eliminates distortions, and there is no need for post-process machining.
- No chromium nitride or carbide precipitations at grain boundaries, which eliminates the possibility of intergranular corrosion.
- After electrochemical pitting corrosion test – there was no pitting corrosion found, while the untreated sample suffered from pitting corrosion.
The achieved results are remarkable the further work that continues with actual clients will help us to further improve our technology and results.
Ionitech Ltd.'s ‘Plasma Nitriding and Nitrocarburising for high wear resistance and high corrosion stability Stainless Steel — PlaSSteel’ project that will be Co-funded by the Horizon 2020 Framework Programme of the European Union.
