Numerical calculation of temperature and phase change during the process of atomizing spray quenching on drilling pipe

A finite element method (FEM) procedure was developed in order to simulate the quenching process for drilling pipe (DP).The calculating model was based on time-temperature-transformation (TTT) diagrams, and incorporated with material properties dependent on temperature. The procedure was used to calculate the temperature-time histories, describe the phase transformations of atomizing spray quenching for DP in the welding zone, and predict the hardness distribution in radius direction after quenching in the zone. The calculated results met well with that of experiments. It was easy to determine the parameters such as volume and pressure of the cooling water and compressed gas by use of the numerical calculation and experiments, because the value of convection coefficient was decided greatly by the mixture of the cooling water and compressed gas. Moreover, the simulating results were helpful not only to design the quenching equipment, but also to optimize the quenching process for DP's welding zone.