ISSN 2594-5327
59º Congresso anual — Vol. 59 , num. 1 (2004)
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An investigation on the effect of Ni on hot ductility of Nb-Ti microalloyed steels has been carried out over the temperature range 800–1000 °C. A small addition of Ni (0.5%Ni) did not show any influence on hot ductility but a higher addition of 1%Ni improved the hot ductility at both slow and fast cooling rates of 0.4 °C/s and 4 °C/s, respectively. This was attributed to Ni aiding in the coarsening of the Ti/Nb carbonitride precipitates. For the same reason, reducing the cooling rate improves the hot ductility in all cases. Cu has also been shown to coarsen these precipitates and a similar explanation may apply to both elements. It is suggested that the Cu and Ni atoms could encourage diffusion by generating excess vacant lattice sites or prolong the lifetime of vacancies generated by the deformation thereby assisting in the formation of TiNb-vacancy complexes that enhance the coarsening of the precipitate particles. For Ti-Nb containing steels, Ni addition is recommended not only as a way to ensure the prevention of hot shortness caused by copper but also by improving the hot ductility by coarsening the microalloy precipitates.
An investigation on the effect of Ni on hot ductility of Nb-Ti microalloyed steels has been carried out over the temperature range 800–1000 °C. A small addition of Ni (0.5%Ni) did not show any influence on hot ductility but a higher addition of 1%Ni improved the hot ductility at both slow and fast cooling rates of 0.4 °C/s and 4 °C/s, respectively. This was attributed to Ni aiding in the coarsening of the Ti/Nb carbonitride precipitates. For the same reason, reducing the cooling rate improves the hot ductility in all cases. Cu has also been shown to coarsen these precipitates and a similar explanation may apply to both elements. It is suggested that the Cu and Ni atoms could encourage diffusion by generating excess vacant lattice sites or prolong the lifetime of vacancies generated by the deformation thereby assisting in the formation of TiNb-vacancy complexes that enhance the coarsening of the precipitate particles. For Ti-Nb containing steels, Ni addition is recommended not only as a way to ensure the prevention of hot shortness caused by copper but also by improving the hot ductility by coarsening the microalloy precipitates.
Palavras-chave
hot ductility, precipitation, nickel
hot ductility, precipitation, nickel
Como citar
Comineli, O.; Luo, H.; Liimatainen, HM.; Karjalainen, L. P..
INFLUENCE OF Ni ALLOYING ON HOT DUCTILITY OF Ti-Nb MICROALLOYED STEELS,
p. 382-389.
In: 59º Congresso anual,
São Paulo, Brasil,
2004.
ISSN: 2594-5327, DOI 10.5151/2594-5327-3639
