SYMPOSIA PAPER Published: 01 January 1950

Observations of the Effect of Sigma on the Mechanical Properties of Columbium-Stabilized Weldments in Austenitic Stainless Steels


A summary of the investigation of 13 weldments in 1 1/2-in, thick T347 stainless steel on the basis of heat treatments given for stress removal reveals that ductility of all weld metal tension test bars is affected by the following variations: 1. Maximum ductility of 30 per cent and over is obtained in the “aswelded” condition with ferrite content between 3 and 8 per cent when no sigma is present. 2. Ductility varying between about 10 to 30 per cent is obtained after heat treatments producing sigma contents from 5 to 1 per cent. 3. Weld metal with ferrite in the as-deposited condition does not always sigmatize to the full extent possible. 4. The size and distribution of the sigma phase varies the ductility. Larger particles of sigma in a segregated pattern are more effective in lowering ductility. 5. Variations of welding technique such as thin and thick weld layers and peening affect the ductility only in so far as the amount of sigma produced on heat treatment.

Author Information

Schmitz, F., W.
A. O. Smith Corp., Milwaukee, Wis.
Scheil, M., A.
A. O. Smith Corp., Milwaukee, Wis.
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Developed by Committee: E04
Pages: 165–181
DOI: 10.1520/STP46111S
ISBN-EB: 978-0-8031-6741-4
ISBN-13: 978-0-8031-6506-9