Effects of microalloying and hot rolling parameters on toughness and yield strength of API X80 grade steel strips

Recently API X80 grade has been increasingly used for UOE pipes and, furthermore, API X100 and X120 grades are being developed. However, the usage of hot rolled API X80 grade for spiral-welded pipes has been limited. This is partly due to metallurgical barriers which are the anisotropy of mechanical properties and the strength drop after pipe forming. Manufacturing conditions and metallurgical parameters causing these barriers have been reviewed. The effect of both size and distribution of MA constituent on the Charpy impact upper shelf energy has been investigated. In addition, the development of API X80 hot rolled strip and commercial production results from a 12,000 tonne API X80 grade order for a linepipe project have been summarised. (AU) Copyright © 2014 Companhia Brasileira de Metalurgia e Mineração (CBMM) All rights reserved.