Abstract
Low transformation temperature welding (LTTW) consumables are characterized by a low martensite start temperature and a large fraction of martensite forming in the weld. It can efficiently reduce the tensile residual stress because the volume expansion associated with the martensitic transformation compensates for the thermal contraction during cooling. In this work, a LTTW wire, designated as EH200B, was created for the arc welding of advanced high-strength steel thin plates. In comparison to conventional ER70S-3 wires, this LTTW wire generated an opposite distortion pattern. Neutron diffraction measurements along the center thickness of the welded plates showed the maximum residual stress along the longitudinal direction (LD) in the weld region, and the heat-affected zone (HAZ) immediately adjacent to the weld region was reduced from ~330 MPa to below 240 MPa by using the LTTW wire. A finite element (FE) model was developed to predict the residual stress distributions of the plates welded under these two wires. The simulation results showed reasonable agreement with the volume-average neutron diffraction data. Compressive residual stress in the weld region using the LTTW wire was predicted by the FE method. Electron backscattered diffraction and x-ray diffraction measurements confirmed ~90% martensite was present in the LTTW weld. The fatigue life of DP980 steel lap joint panels using EH200B wire nearly doubled that of ER70S-3 wire. This improvement was attributed to the high strength and low LD residual stress in the weld and HAZ immediately adjacent to the weld.
| Original language | English |
|---|---|
| Pages (from-to) | 124S-134S |
| Journal | Welding Journal |
| Volume | 99 |
| Issue number | 4 |
| DOIs | |
| State | Published - Apr 2020 |
Funding
This research was financially sponsored by the U.S. Department of Energy (DOE) Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies, as part of the Lightweight Materials Program, through a subcontract from Oak Ridge National Laboratory (ORNL). ORNL is managed by UT-Battelle LLC for the U.S. Department of Energy under Contract DE-AC05-00OR22725. This research used resources at the High Flux Isotope Reactor, a DOE Office of Science User Facility operated by the ORNL. The authors acknowledge the National Science Foundation, Industry and University Cooperative Research Center, and The Manufacturing and Materials Joining Innovation Center for the opportunity to conduct this research, as well as Devasco International for providing the experimental wires and supplementary funding. The authors would also like to gratefully acknowledge ESI Group for making the SYSWELD software available to the researchers of the Center for Welding, Joining and Coatings Research of the Colorado School of Mines. Their technical support and discussion are also kindly appreciated. The authors also acknowledge T. Alghamdi and Sindhu Thomas for their prior work related to the development of the EH200B alloy.
Keywords
- Gas Metal Arc Welding
- Low Transformation Temperature Welding Consumables
- Neutron Diffraction
- Numerical Simulation
- Weld Residual Stress