Effects of Heat Input on Microstructure, Corrosion and Mechanical Characteristics of Welded Austenitic and Duplex Stainless Steels: A Review

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Abstract:In this study, an attempt on pulsed-fiber laser welding on an austenitic-duplex stainless steel butt joint configuration was investigated. The influence of various welding parameters, such as beam diameter, peak power, pulse repetition rate, and pulse width on the weld beads geometry was studied by checking the width and depth of the welds after each round of welding parameters combination. The weld bead dimensions and microstructural progression of the weld joints were observed microscopically. Finally, the full penetration specimens were subjected to tensile tests, which were coupled with the analysis of the fracture surfaces. From the results, combination of the selected weld parameters resulted in robust weldments with similar features to those of duplex and austenitic weld metals. The weld depth and width were found to increase proportionally to the laser power. Furthermore, the weld bead geometry was found to be positively affected by the pulse width. Microstructural studies revealed the presence of dendritic and fine grain structures within the weld zone at low peak power, while ferritic microstructures were found on the sides of the weld metal near the SS 304 and austenitic-ferritic microstructure beside the duplex 2205 boundary. Regarding the micro-hardness tests, there was an improvement when compared to the hardness of duplex and austenitic stainless steels base metals. Additionally, the tensile strength of the fiber laser welded joints was found to be higher when compared to the tensile strength of the base metals (duplex and austenitic) in all of the joints.

Section: Metallography and Visual Examinationmentioning

confidence: 99%

“…With an increment in the Creq/Nieq ratio (1.5 to 2.0), the primary solidification is promoted by ferrite. Duplex stainless steels are those that solidify completely to ferrite (Creq/Nieq > 2) [39]. They exhibit cracking vulnerability to indeterminate alloys that experience complete austenitic and ferritic/austenitic solidifications [33].…”

Section: Microhardnessmentioning

confidence: 99%

Fiber Laser Welding of Dissimilar 2205/304 Stainless Steel Plates

Mohammed

Ishak

Ahmad

et al. 2017

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“…Applied to oil extraction structures, pipes, and pressure vessels, these steels combine good mechanical properties with an excellent ability to withstand the corrosive media to which they are exposed. These characteristics are directly linked to the biphasic structure formed, composed basically of ferrite and austenite in approximately equal proportions [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. For the application of these steels, welding processes are usually involved, and weldability is another positive point, as DSS and SDSS are weldable by almost all processes available in the market.…”

Section: Introductionmentioning

confidence: 99%

“…In practice, in some situations in the field where the repair in steel is necessary, the professional can have only the option of autogenously welding. Another point of emphasis in studies of these steels is the heat input applied [7]. Reference values for this heat input are around 0.5-3.0 KJ/mm.…”

Section: Introductionmentioning

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

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.

“…The cracked surface oxidation initially facilitates the propagation of cracking, while the continued growth is smoothed by the combined effects of crack filling of the cast material, oxidation and ductility of the tool material. The interaction of a molten metal with a die increases the surface temperature, raising it more than the temperature of the interior [11][12][13][14][15][16][17][18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Thermally-Induced Crack Evaluation in H13 Tool Steel

Abdulhadi

Ahmad

Ismail

et al. 2017

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This study reported the effect of thermal wear on cylindrical tool steel (AISI H13) under aluminum die-casting conditions. The AISIH13 steels were immersed in the molten aluminum alloy at 700 • C before water-quenching at room temperature. The process involved an alternating heating and cooling of each sample for a period of 24 s. The design of the immersion test apparatus stylistically simulated aluminum alloy dies casting conditions. The testing phase was performed at 1850, 3000, and 5000 cycles. The samples were subjected to visual inspection after each phase of testing, before being examined for metallographic studies, surface crack measurement, and hardness characteristics. Furthermore, the samples were segmented and examined under optical and Scanning Electron Microscopy (SEM). The areas around the crack zones were additionally examined under Energy Dispersive X-ray Spectroscopy (EDXS). The crack's maximum length and Vickers hardness profiles were obtained; and from the metallographic study, an increase in the number of cycles during the testing phase resulted in an increase in the surface crack formation; suggesting an increase in the thermal stress at higher cycle numbers. The crack length of Region I (spherically shaped) was about 47 to 127 µm, with a high oxygen content that was analyzed within 140 µm from the surface of the sample. At 700 • C, there is a formation of aluminum oxides, which was in contact with the surface of the H13 sample. These stresses propagate the thermal wear crack length into the tool material of spherically shaped Region I and cylindrically shape Region II, while hardness parameters presented a different observation. The crack length of Region I was about 32% higher than the crack length of Region II.