Influence of Chemical Composition on the Mechanical and Microstructural Properties of High Strength Steel Weld Metals Submitted to PWHT

Abstract

The development of new filler metals for offshore industry is challenging because high strength and toughness levels are required after post-welding heat treatment (PWHT) is applied to reduce residual stresses. The higher chromium contents added to the chemical composition of welding consumables to attain the required ultimate tensile strength are usually associated with reduced toughness. This work presents a comparative analysis of the behavior of two high strength steel weld metals with different Cr-Mo and Mn-Ni additions that were submitted to PWHT. Weld metals obtained by shielded metal arc welding process were evaluated using mechanical tests (Charpy-V notch and Vickers microhardness) and microstructural analysis (scanning electron microscopy and electron backscattered diffraction) conducted in samples removed from the center line of weld deposits, both in the as-welded and heat-treated (600 °C for 1 h) conditions. Although similar results were obtained in the as-welded condition, different behaviors were observed after PWHT. While impact toughness for Cr-Mo additions was reduced by carbide precipitation, as predicted by thermo-calc simulation, weld metal based on Ni-Mn addition exhibited improvements after PWHT because the predominantly martensite microstructure was tempered. This makes the latter more appropriate for weldments submitted to PWHT.

Evaluation of the Chemical Composition of Coatings Present on AWS A5.1 E6013 Welding Electrodes

“…Dentre os metais analisados o Cr foi o que apresentou o maior teor nas amostras de revestimento, chegando a 881,6 mg m -3 (Tabela 2). Este metal, juntamente com o Ni, Co e o Cu podem estar presentes nos revestimentos para garantir um aumento da resistência mecânica, da resistência à oxidação e da condutividade térmica da junta soldada [21][22][23][24]. Os teores de Cr, Ni, Co e Cu observados estão consideravelmente maiores que o permitido pelo limite de exposição ocupacional fornecido pela Conferência Americana de Higienistas Industriais Governamentais, do inglês: American Conference of Governmental Industrial Hygienists (ACGIH) que fixam os teores em 0,5 mg m -3 , 1,00 mg m -3 , 0,02 mg m -3 e 0,2 mg m -3 para Cr, Ni, Co e Cu respectivamente [9].…”

Welding of S1100 Ultra high‐Strength Steel Plates with Matching Metal‐Cored Filler Wire: Microstructure, Residual Stresses, and Mechanical Properties

“…The alloying elements Ni, Mo, and Cr are mostly used for solid solution strengthening and for improving the phase transformation of austenite during the cooling process. [ 14 ] The alloying elements Ti, Nb, and V form nanoscale precipitates with minimum lattice misfit and can effectively prevent dislocation slipping or twinning. [ 15 ] As the actual contents of the alloying elements determine the microstructures of the WM and of the HAZ in fusion welding processes, they play an important role with regard to controlling the mechanical properties of the weldments.…”

Parametric Optimization of the GMAW Welding Process in Thin Thickness of Austenitic Stainless Steel by Taguchi Method

“…However, the welding joints are often the weakest links in assemblies [9]. The quality of the weld depends on the bead geometry [10], metallurgical and mechanical characteristics [11], chemical composition [12], and input parameters such as voltage, current, electrode type, flux and gas type, welding position, travel speed, and others [4] making the task of finding the best parameters quite challenging [13]. If the welding parameters are not correctly chosen, they can lead to welded joints with high levels of residual stresses [14,15], geometric distortions [16], and discontinuities [17,18].…”