Welding Metallurgy and Weldability of Naval Structural Damping Steels
Abstract
High Mn steels show promise for naval applications where vibration control and noise damping are important design considerations, bu,t currently available alloys do not meet the strength requirements for naval use. Companion proposals have been submitted by Massach,usetts Institute of Technology, Northwestern University, and Carderock Naval Surface Warfare Center for developing new high Mn alloy,s that retain their damping capacity at increased strength levels. Most structural components made from these alloys for naval appli,cations require fabrication by fusion welding. Thus, it is critical that the new alloys are readily weldable and exhibit good resist,ance to various forms of cracking during welding. In addition, microstructural evolution and localized changes in mechanical propert,ies induced by the high heating and cooling rates associated with welding need to be thoroughly understood. This proposal describes,an integrated computational and experimental plan that is designed to develop a detailed understanding of phase transformations and,the resultant mechanical properties and weldability of new high Mn steels for naval applications. Modeling results will first be use,d to understand how variations in composition control the solidification behavior (i.e., primary phase transformation sequence, soli,dification temperature range, and formation of secondary phases at the end of solidification) and resultant weldability. This aspect, of the program will include changes to both the base metal composition (that may be needed for enhanced strength) as well as inclus,ion of commercial filler metals that may be used in the near term. Based on the modeling results and input from other team members,,a wide range of alloy compositions will then be used for solidification cracking evaluations, differential thermal analysis, and det,ailed microstructural characterization studies. Research will also be done to establish how microstructural evolution during solidif,ication and post weld heat treatment influences local changes in properties. These results will support interpretation of the full s,cale mechanical property evaluations conducted by other project team members. From a scientific perspective, this proposed program w,ill provide a detailed understanding of composition-microstructure-weldability/property relations in these new steels along with val,idated/refined modeling tools for alloy design. From an engineering perspective, this program will lead to the development of new st,eels for naval applications that provide improved combinations of strength and damping capacity that are also readily weldable.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 13, 2022
- Source ID
- N000142212517
Entities
People
- John DuPont
Organizations
- Lehigh University
- Office of Naval Research
- United States Navy