Session: CS-07-02: Recent Developments in ASME Codes and Standards - 2

Paper Number: 83919

83919 - An Initial Assessment of the Creep-Rupture Strengths for Weldments With Alloy 800H Base Metal and Alloy 617 Filler Metal 

In Section III, Division 5 of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code, Alloy 800H is qualified for elevated-temperature nuclear construction for temperatures up to 760°C and a maximum service life of 300,000 hours. There are two permissible filler metals for Alloy 800H weldments specified in Division 5: ENiCrFe-2 (Alloy A) and ERNiCr-3 (Alloy 82). In Division 5, the weldment creep rupture strength is represented as the product of the stress rupture factor (SRF) and the expected minimum stress-to-rupture of the base metal. The SRF values are determined as the ratio of the average creep rupture strength of the weldment and that of the base metal. For the permissible temperatures and service lives, the SRF values range from 1.00 at low temperatures and short lifetimes to 0.59 and 0.54 at 760°C and 300,000-hour life for Alloy 800H weldments comprised respectively of Alloy A and Alloy 82 filler metals. Low creep-rupture strengths of these weldments may restrict the design envelope for elevated-temperature nuclear construction with Alloy 800H. As a result, an alternative filler metal is desired to improve the creep-rupture strengths of Alloy 800H weldments for the qualified temperatures and service lives.

 

This work investigates an overmatched filler metal. Specifically, the work studies a weldment with Alloy 800H base metal and Alloy 617 filler metal fabricated by automated gas tungsten arc welding. A scoping creep-rupture test program was conducted of cross-weld specimens at temperatures ranging from 700 to 1,000°C. Preliminary results on the creep-rupture strength of the Alloy 800H weldment with Alloy 617 filler metal do not show significant improvement compared to the filler metals currently qualified in Division 5 for Alloy 800H weldments. Consequently, work is in progress to investigate a matching filler metal.

Presenting Author: Ryann Rupp Idaho National Laboratory

Presenting Author Biography: Dr. Ryann Rupp is a Materials Engineer at Idaho National Laboratory. Her primary research interests involve the relationships between processing, microstructure, and mechanical properties. She specializes in characterizing elevated-temperature structural alloys for nuclear and concentrated solar power applications. Ryann is a member of various ASME Boiler and Pressure Vessel Code committees and is secretary of the Section III Task Group on Division 5 Advanced Manufactured Components. Dr. Rupp graduated from the University of Texas at Austin with a Ph.D. in Materials Science and Engineering.

Authors:

Ryann Rupp Idaho National Laboratory
Ting-Leung Sham Idaho National Laboratory