Banca de DEFESA: JUSCELINO MENDES PRADO

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : JUSCELINO MENDES PRADO
DATA : 28/02/2020
HORA: 14:00
LOCAL: Sala 330 - Prédio Principal
TÍTULO:

Influence of heat input on the heated affected zone of high strength microalloyed steels with vanadium an niobium for reinforcing bars.

PALAVRAS-CHAVES:

Welding, Microalloyed Steel, HAZ, Heat Input.

PÁGINAS: 102
GRANDE ÁREA: Engenharias
ÁREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Metalurgia de Transformação
ESPECIALIDADE: Soldagem
RESUMO:

Microallyed steels with niobium and vanadium have been outstanding in recent years, this is due to the great potential of use in structural applications, especially in long products of high strength. Addition of alloying elements, together with the TermoMechanical Control Process, provides formation of homogeneous microstructures, besides increasing the strength concomitantly with the increase of. This occurs due to the grain refinement and the formation of precipitates, which is a phenomenon peculiar to high strength microalloyed steels (HSLA). However, the use of micro-alloying elements has not yet been extensively studied, especially for steels with high equivalent carbon content. A high value of equivalent carbon added by elements such as V and Nb can lead to deleterious effects on the material if no precautions are taken during the welding process. Studies indicate that the main problems found in the welding of microallyed steels are related to heat input, which may affect the HAZ characteristics of these metals. Thus, depending on the chosen heat input, the value of equivalent carbon and on the type of element, it will be possible to have changes in the width, hardness and microstructure of the HAZ. This may affect the characteristics of these steels when applied as reinforcing bars. Thus, the objective of this work was to evaluate the effects of heat input and niobium addition on the HAZ of high carbon equivalent vanadium microalloyed steels for application as reinforcing bars. Thus, welds were carried out on V and NbV microalloyed steel rebars by the GTAW (Gasshielded Tungsten Arc Welding) process. The results indicate the coarse grains region of HAZ as the most critical place during welding. Abnormal grains (> 100µm) for welding with high heat input or the presence of martensite in low heat input were observed. Both phenomena are also related to Pcm (critical metal parameter) and the niobium content, which may favor or delay these occurrences. On the other hand, the results do not indicate softness in any region of the HAZ, proving to be an advantage, either in terms of applied heat input or by the addition of niobium in the steels.

MEMBROS DA BANCA:
Externo à Instituição - ALEXANDRE QUEIROZ BRACARENSE - UFMG
Presidente - CLAUDIO TURANI VAZ
Externo à Instituição - HELDER CARVALHO FERREIRA - UFMG