Objective:
The project goal is to implement silicate-free (SF) gas metal arc welding technology mitigating need for multipass weld inter-pass cleaning. The project objectives are:
- Develop matrix of welding procedures for tandem gas metal arc welding (T-GMAW) process (target implementation process) at min and max heat inputs for two HSLA-65 steel plate thicknesses.
- Evaluate T-GMA properties using representative welding procedure qualification tests.
- Evaluate soundness per MIL-STD-271 and Tech Pub -248 testing requirements.
- Evaluate procedure qualification (Bends, Tensiles, and Charpys) properties per
Tech Pub -248 procedure test requirements and compare results to MIL-70S-6.
- In addition, evaluate typical deposit composition, microhardness distribution
(maps) and microstructure to correlate any microstructure changes to
properties.
- Determine next steps to drive transition into shipbuilding.
Summary:
In gas metal arc welding (GMAW) of shipbuilding steels, silicates (small slag islands) form on the weld deposit surface and must be removed during multi-pass welding of steel joints and before structure painting. Silicate cleaning processes have a negative impact on welding productivity. New GMAW electrode technology
needs to be developed and implemented to offer silicate free deposition and acceptable properties.
Key Deliverables / Benefits:
Silicate cleaning processes have a negative impact on welding productivity. Silicate cleaning can often take as long as welding. Multi-pass butt joint welding productivity can easily increase by 50 to 100% (2X) by eliminating inter-pass silicate cleaning procedures and minimizing visual examinations. This is a high priority at Ingalls and other shipyards to maximize return on investment of automated panel lines.
Overview
Project Team:
- EWI, HII-Ingalls Shipbuilding, NSWCCD
April 2023 – April 2024
NSRP INVESTMENT $145K
