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Effect of microstructure on the mechanical properties of microplasma arc welded austenitic stainless steels
Date Issued
01-02-1992
Author(s)
Rao, Kalvala Prasad
Abstract
Austenitic stainless steels of type 308Cb and 309Cb (0.5 mm thick) were autogenously welded by a microplasma welding process which resulted in ferrite contents of 6 and 20 FN, respectively.The samples were subjected to postweld heat treatment (PWHT) at 600, 750, 900 and 1050$+$DEG$/C for 5 hours duration and water-quenched. X-ray diffraction and metallographic studies were performed to identify the microstructures of the weld metals before and after PWTH. The tensile strength, Charpy energy (room temp.) and stress intensity factor were measured. Microstructural studies indicated that as-welded metals contain only delta ferrite and austenite. It was found that an increase in ferrite content increases strength and decreases toughness. 308Cb weld metal did not exhibit significant change in strength after PWHT at various temperatures, while there was a significant increase in the case of 309Cb samples. Charpy energy values, in general, decrease after PWHT. A drastic decrease in Charpy energy was noted for 309Cb weld metals after PWHT at 600 and 750$+$DEG$/C The Charpy energy values of the samples were also equal to those of the weld metals after PWTH at 1050$+$DEG$/C.
Volume
29