CLADDING TECHNOLOGY SHANXI CO., LTDTemperature Field Simulation of Dual-Wire Submerged Arc Cladding Based on ABAQUS
Background and Motivation
Submerged arc welding (SAW) is one of the most productive and economical processes for thick overlay cladding applications, particularly for large-area corrosion-resistant cladding on pressure vessels and structural components. Dual-wire SAW cladding offers enhanced deposition rates and improved layer uniformity compared to single-wire configurations. However, the complex thermal cycles associated with dual-wire deposition create significant challenges in predicting residual stresses, microstructure evolution, and potential defects. This study employs ABAQUS finite element analysis to model the temperature field distribution during dual-wire SAW cladding, providing valuable insights for process optimization.
Core Technical Content
Numerical Model Description
The study establishes a three-dimensional transient thermal model of dual-wire SAW cladding on a steel substrate. The model accounts for the moving heat source from two independently driven wire electrodes, the flux coverage effect, and the convective and radiative heat losses from the surface. The heat source is modeled using a double-elliptical Gaussian distribution to represent the arc energy input from each wire.
| Model Parameter | Value / Range |
|---|---|
| Substrate material | Q345R (16MnR) |
| Wire diameter | 1.6 mm (both wires) |
| Wire travel speed | 500-700 mm/min |
| Welding voltage | 28-32 V |
| Welding current | 350-450 A |
| Arc efficiency | 0.75-0.85 |
| Heat source type | Double-elliptical Gaussian |
| Mesh element type | 8-node brick (DC3D8) |
| Time step | Adaptive (0.05-0.5 s) |
Key Simulation Results
The temperature field simulation reveals several important phenomena. First, the dual-wire configuration produces a wider and shallower heat-affected zone compared to single-wire SAW, which is beneficial for reducing cracking susceptibility but may increase dilution in the first pass. The peak temperature at the weld pool surface reaches approximately 2200-2400°C, while the solidification front temperature (1538°C for carbon steel) defines the solidification boundary.
The cooling rate analysis shows that the cooling rate at 800°C (C800) is significantly influenced by the wire spacing and travel speed. A wire spacing of 8-12 mm with a travel speed of 600 mm/min yields a C800 in the range of 10-25°C/s, which is suitable for producing a fine-grained microstructure in the overlay layer. The simulation also demonstrates that the thermal cycling effect from subsequent passes modifies the microstructure of previously deposited layers, with the reheat temperature reaching 600-800°C in the last deposited layer.
Comparison of Single-Wire and Dual-Wire Thermal Fields
| Parameter | Single-Wire SAW | Dual-Wire SAW |
|---|---|---|
| Peak temperature (°C) | 2400-2600 | 2200-2400 |
| Heat-affected zone width (mm) | 15-20 | 25-35 |
| C800 (°C/s) | 20-40 | 10-25 |
| Deposition rate (kg/h) | 12-18 | 22-32 |
| Thermal efficiency (%) | 70-80 | 75-85 |
Engineering Practice Integration
The simulation results have direct implications for the design of welding procedures for thick cladding layers. The reduced cooling rate in dual-wire SAW means that the risk of martensite formation in the overlay layer is lower, which is advantageous for achieving good toughness. However, the wider heat-affected zone in the base metal requires careful consideration of the base metal's susceptibility to temper embrittlement or grain growth.
For pressure vessel fabrication under NB/T 47002 or ASME VIII Div.1, the welding procedure qualification must account for the thermal effects predicted by the simulation. The residual stress distribution derived from the coupled thermo-mechanical analysis indicates compressive stresses in the overlay layer and tensile stresses in the base metal near the fusion line, which has implications for fatigue performance and stress corrosion cracking resistance.
Process Optimization Recommendations
- The wire spacing should be maintained at 8-12 mm to optimize the thermal overlap and ensure uniform layer profile.
- Travel speed adjustments should be made based on the predicted C800 values to achieve the desired microstructure in the overlay layer.
- For multi-pass cladding, the number of passes should be planned to ensure that the reheat temperature of the previous pass does not exceed 800°C, which could cause grain coarsening.
- The simulation results should be validated against thermocouple measurements during actual welding trials to calibrate the model for specific production conditions.
Reflections and Study Insights
This study exemplifies the growing importance of numerical simulation in modern welding engineering. The ABAQUS-based thermal field model provides a powerful tool for predicting the thermal history of dual-wire SAW cladding, which is essential for microstructure prediction and defect prevention. The key insight is that the dual-wire configuration fundamentally alters the thermal cycle compared to single-wire SAW, and this alteration must be accounted for in welding procedure design. Engineers should view numerical simulation not as a replacement for welding trials but as a complementary tool that reduces the number of trial welds and accelerates the procedure qualification process. The study also highlights the need for accurate material property data at elevated temperatures, as the thermal conductivity and specific heat of both the base metal and the overlay material significantly influence the simulation accuracy.