Simulação numérica do crescimento de diâmetro externo de tubos de aço sem costura durante a têmpera em tanque na Vallourec soluções tubulares do Brasil S.A. (VSB)

Abstract

Heat treatment is an important seamless pipe production step, utilized to enhance the properties of the final product such as mechanical strength, hardness and dimensional accuracy. Quenching is a common step in this heat treatment, involving the fast cooling of previously austenitized parts and leading to a phase transformation from austenite to hard martensite in the material. Quenching is a critical stage because it can be also responsible for geometric distortions in steel pipes, such as outside diameter growth. The final size prediction becomes key to assure the quality and dimensional requirements of the product. The objective of this study was to use simulations, based on the Finite Element Method (FEM), for tube water quenching in tanks in order to estimate the final outside diameter of a seamless low carbon steel pipe. This work was a first approach to develop a methodology for predicting quenched pipes distortion and it was developed in three stages: temperature measuring in the pipe during the quenching process; heat transfer coefficient (HTC) calculation, and distortion calculation. Finally, pipe distortion was predicted taking phase transformation and deformation into account. The results of the simulations were similar to industrial results for as quenched pipes.