Mechanical performance of heavy gauge press hardened steel modified with Nb and Mo additions on GMAW welded joints
Desempenho mecânico de aço endurecido de prensa de medidor pesado modificado com adições de Nb e Mo em juntas soldadas de GMAW
Tiago Führ, Diego Tolotti, Daniela Bertol, João Henrique Corrêa de Souza, Angélica Paola de Oliveira Lopes
Abstract
The principle of hot stamping is directly related to the opportunities offered by the chemical composition of boron-alloyed steel due to the process amplitude window for quenching. The 22MnB5 + NbMo steel presents a microstructure composed of ferrite-perlite with yield limit and resistance limit of approximately 450 and 600 MPa, respectively. After the workpiece is hot stamped, the microstructure obtained is completely martensitic, and can reach strength limit values exceeding 1500 MPa. This paper presents a study on the 22MnB5 weldability, mechanical and microstructural properties when designed with Nb and Mo additions, hot formed, and welded using three different wires (AWS A5.28 ER110S-G, E110C-G M H4 and ER70S-6), evaluating these properties through metallographic and macrographic analysis, tensile tests and Charpy impact fractography. According to the results, it is possible to weld 22MnB5 + NbMo press hardened steels, with best condition obtained in this work using ER110S-G wire, considering fracture toughness and satisfactory tensile test results.
Keywords
Resumo
O princípio da estampagem a quente está diretamente relacionado às oportunidades oferecidas pela composição química do aço ligado a boro devido à amplitude da janela no processo de têmpera. O aço 22MnB5 + NbMo apresenta uma microestrutura composta por ferrita-perlita com limite de escoamento e limite de resistência de aproximadamente 450 e 600 MPa, respectivamente. Após a peça estar estampada a quente, a microestrutura obtida é completamente martensítica, podendo atingir valores limite de resistência superiores a 1500 MPa. Este trabalho apresenta um estudo sobre a soldabilidade, propriedades mecânicas e microestruturais do aço 22MnB5 quando refinado com adições de Nb e Mo, conformado a quente e soldado utilizando três diferentes arames classificados pela norma AWS A5.28 (ER110S-G, E110C-G M H4 e ER70S-6), avaliando essas propriedades por meio de análise metalográfica e macrográfica, ensaios de tração e fractografia de impacto Charpy. Os resultados mostram que é possível soldar o aço 22MnB5 + NbMo temperado com sucesso, sendo a melhor condição obtida neste trabalho ao usar o arame ER110S-G, considerando tanto a tenacidade à fratura quanto os resultados satisfatórios nos ensaios de tração.
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References
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Submitted date:
06/10/2019
Accepted date:
07/19/2021
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