Effect of Some Heat Treatments on Microstructure and Mechanical Properties of a Microalloyed Low Carbon Steel Aiming to Attend the Oil and Gas Industry
Tainan Ferreira Muniz1; Vicente Braz Trindades2; Geraldo Lúcio de Faria1
1 Universidade Federal de Ouro Preto; 2 Vallourec Sumitomo Tubos do Brasil
doi:10.20906/CPS/COB-2015-0898
Resumo
The API linepipe steels have a great technological importance to oil and gas industry development around the world. Nowadays, the metallurgical challenge is to produce steels with high mechanical properties and low fraction of alloying elements. In this context, this work presents a study about the effect of some heat treatments on microstructure and mechanical properties of microalloyed low carbon aiming to get the API X65 grade. Specimens were submitted to different heat treatments as normalization, quenching and tempering with different heat cycle combinations. In normalizing followed by tempering heat treatments, the material was cooled in air without agitation. In quenching heat treatments, the steel was heated until 920oC, with an residence time of 15 minutes, and cooled in water at environment temperature. Specimens were submitted to tension, Charpy impact and Vickers hardness tests. Microstructural and microfractographic analysis were conducted in optical and scanning electronic microscopes. The obtained results showed that the normalized (and variations) samples did not get the API X65 grade specifications, as well the quenched (without tempering). The other heat treated samples presented the mechanical properties predicted by API X65 standard, been a viable procedure.
Palavras-chave: API X65; Heat Treatment; Mechanical Properties