Numerical Predictions for the Thermal History, Microstructure and Hardness Distributions at the HAZ during Welding of Low Alloy Steels

Xavier, Carlos Roberto; Delgado, Horácio Guimarães; Castro, José Adilson de; Ferreira, Alexandre Furtado

doi:10.1590/1980-5373-mr-2015-0068

Cited by 15 publications

(20 citation statements)

References 29 publications

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“…The model takes into account the heat transfer by radiation, convection and conduction. The mass transfer due to consumable deposition and dilution within metal base melting and solidification are considered and the properties changes due to local composition and temperature are taken into account [9][10][11][12] . The temperature distribution is obtained by solving the energy conservation, shown in Equation (1) 9-12…”

Section: Numerical Proceduresmentioning

confidence: 99%

“…However, for large equipments and welding pieces it is common to use multiple pass welding procedure and some regions can relay into the gap of temperature and time suitable to form the deleterious phases. Thus, the design of an adequate welding procedure is important to make or repair the equipment to work under safety conditions [9][10][11][12] . In this work we propose an approach that could help on this task.…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, the computer code used has been continuously updated by the authors and applied for different materials and welding conditions 3,6,[9][10][11][12] . In this paper we introduce new features to improve the model capability such as routines for kinetics of phase transformations for super duplex stainless steels 7,8 .…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2018

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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.

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Section: Numerical Proceduresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

et al. 2018

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“…In order to monitor and estimate these variables during welding procedures, accurate mathematical models are important allies. We used a previously developed mathematical model to discuss the transient temperature distributions and cooling rates, and hence the precipitates formation [15][16][17]. The model is based on the transient heat equation with moving double ellipsoid heat source accounting for the heat input and velocities of the torch.…”

Section: Temperature Evolution and Cooling Ratesmentioning

confidence: 99%

“…The heat input constant parameters, a, b f , c, and b r , are selected to account for the torch heat distribution. These constant parameters were assumed based on previous work [15][16][17]. The factors f f and f r were assumed as 0.6 and 1.4 respectively, while η, efficiency of heat transfer was assumed 0.80 for the calculations.…”

Section: Temperature Evolution and Cooling Ratesmentioning

confidence: 99%

Microstructural, Mechanical, and Electrochemical Analysis of Duplex and Superduplex Stainless Steels Welded with the Autogenous TIG Process Using Different Heat Input

Fonseca

Barbosa

Ferreira

et al. 2017

Metals

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Duplex Stainless Steels (DSS) and Superduplex Stainless Steels (SDSS) have a strong appeal in the petrochemical industry. These steels have excellent properties, such as corrosion resistance and good toughness besides good weldability. Welding techniques take into account the loss of alloying elements during the process, so this loss is usually compensated by the addition of a filler metal rich in alloying elements. A possible problem would be during the welding of these materials in adverse conditions in service, where the operator could have difficulties in welding with the filler metal. Therefore, in this work, two DSS and one SDSS were welded, by autogenous Tungsten Inert Gas (TIG), i.e., without addition of a filler metal, by three different heat inputs. After welding, microstructural, mechanical, and electrochemical analysis was performed. The microstructures were characterized for each welding condition, with the aid of optical microscopy (OM). Vickers hardness, Charpy-V, and cyclic polarization tests were also performed. After the electrochemical tests, the samples were analyzed by scanning electron microscopy (SEM). The SDSS welded with high heat input kept the balance of the austenite and ferrite, and toughness above the limit value. The hardness values remain constant in the weld regions and SDSS is the most resistant to corrosion.

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Microstructural and Thermal Characterization of 316L + WC Composite Coatings Obtained by Laser Cladding

et al. 2020

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Herein, a metal matrix composite (MMC) composed of 316L stainless steel and 20% in volume of tungsten carbides (WC), fabricated by laser cladding (LC) is considered. LC is an additive manufacturing technique, characterized by ultrafast cooling rates and limited diffusion, thus giving rise to out-of-equilibrium microstructures. The microstructure of the MMC is found to consist of partially dissolved WC well distributed in an austenitic matrix reinforced by a network of reaction carbides. Those mixed reaction carbides are formed from a liquid enriched in W and C due to the dissolution of the original WC in contact with the molten metal during deposition. Distribution, chemical composition, crystallographic features, and stability of the different phases are characterized in details by combining electron microscopy, electron backscattered diffraction, and dilatometry. This combination of techniques allows to distinguish among M 6 C, M 23 C 6 , M 4 C, and WC 1-x carbide, belonging to the FeW -C system and all exhibiting a face-centered cubic lattice. Moreover, results of reverse thermal analyses are considered together with microstructural data to elucidate the genesis of this complex microstructure, differentiating the phases formed in the melt pool, in the vicinity of partially dissolved WC and in the heat-affected zone between two successive tracks.

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Numerical Predictions for the Thermal History, Microstructure and Hardness Distributions at the HAZ during Welding of Low Alloy Steels

Cited by 15 publications

References 29 publications

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

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

Microstructural, Mechanical, and Electrochemical Analysis of Duplex and Superduplex Stainless Steels Welded with the Autogenous TIG Process Using Different Heat Input

Microstructural and Thermal Characterization of 316L + WC Composite Coatings Obtained by Laser Cladding

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