The Effect of Welding Procedure on All-weld Metal Mechanical Properties and Microstructure of Ferritic High Strength Steel deposited with Tubular Wire

HERNÁN G. SVOBODA, N. MABEL RAMINI DE RISSONE, ESTELA S. SURIAN, LUIS A. DE VEDIA

SOLDAGEM E INSPEçãO

Asociacao Brasileira da Soldagem

Lugar: San Pablo; Año: 2007 vol. 12 p. 124 - 132

0104-9224

The main concern regarding the all-weld metal metallurgical design of consumables depositing low and medium strength weld deposits of the C-Mn-Ni-Mo and C-Mn-Ni-Mo-Cr systems is the achievement of adequate toughness, but nevertheless tensile requirements must also be met and these are in many cases difficult to obtain. In the present work, the relationships between welding process parameters, gas shielding composition, heat input, microstructure and mechanical properties were studied for the all weld metal deposited with gas shielded tubular electrodes (both metal and flux cored ones)of the ANSI/AWS A5.29-98 type using the semiautomatic process. Charpy-V notch toughness, tensile testing and hardness measurements were conducted along with light microscopy analysis in order to correlate the mechanical properties with microstructure. The results showed that the shielding gas composition affects the chemical composition of the weld deposit and this influences the microstructure development. Heat input determines cooling rates and affects the austenite decomposition. Due to the basicity of the flux cored wires employed, the oxygen content in the deposits was significantly lower than in weld deposits obtained with similar metal cored wires. This fact may be related to a reduction in the primary austenite grain width in the flux cored deposits which may be related to the inclusion content. The toughness values amply satisfied the standard requirements, while tensile properties were sensitive to welding process parameters.