Effects of Local Heat Input Conditions on the Thermophysical Properties of Super Duplex Stainless Steels (SDSS)

Abstract

The properties of the super duplex stainless steels (SDSS) are strongly affected by the thermal history imposed by welding procedures. The controlled dual phase microstructure (ferrite and austenite) guarantee excellent mechanical properties such as mechanical strength and corrosion resistance, in addition to small thermal expansion coefficient and high thermal conductivity. In this paper, we newly proposed a model able to predict the thermal history of the welding pieces coupled with local mechanical properties developed during welding procedure that combine the effects of temperature and phase changes during welding. We applied inverse method to fit the thermophysical parameters based on measured data. The model was verified by comparing measured and predicted temperature profiles using thermocouples located within the heat affected zone. Thus, an inverse method was implemented to obtain the parameters fitting for the grain growth evolution compatible with the final microstructure and grain size measured using SEM images and stereological techniques. We demonstrated that very small amount of non-equilibrium deleterious phases and nanosized precipitated are expected during the welding procedures depending upon the local conditions of temperature, compositions and alloying dilution evolutions.

Influence of the Interpass Welding Temperature on Microstructure and Corrosion Resistance of Superduplex Stainless Steel SAF 2507

“…According to Ramirez et al 14 , intragranular austenite is obtained due to the thicker grains formed in this region. The explanation follows the classical mechanism confirmed by previous results 11, [18][19][20][21][22][23][24][25][26][27] .…”

Effect of Sigma Phase Precipitation on Mechanical Behavior and Pitting Corrosion of Duplex Stainless Steel

“…From a practical standpoint, sigma phase precipitation can be encountered during the welding process if the cooling rate from 1200 to 800°C is too slow. This usually occurs because either the heat input is too great or the interpass temperature is too high [15,16]. Incorrectly heat treated DSS may also suffer from sigma phase precipitation.…”

Strain Rate Sensitivity Analysis of Duplex and Superduplex Steels in Tensile Tests

“…Many studies have been performed about microstructural and metalurgical aspects of these alloys (weldability, aging, heat treatments, phases, etc. for instance see [2][3][4][5][6][7][8][9][10][11][12] , but only a few about the phenomenological aspects of the macrossopic mechanical behavior, mainly concerned with Finite Element simulations 9,10 . It is not the goal of the present paper to perform an extensive review of these studies, but the previously mentioned references give a reasonable idea of the research in thie area.…”