Temperature Field Simulation of Dual-Wire Submerged Arc Cladding Based on ABAQUS

Literature Overview

This 2012 publication in Welding Technology, authored by Zhou Boyun, Zhang Lian, Zhang Juan, and Wu Di from Shanxi Electric Power Vocational College, Liaoyang Petrochemical Engineering, Liaoyang Chemical Machinery, and Shenyang University of Technology respectively, presents a finite element analysis of the temperature field during dual-wire submerged arc welding (SAW) overlay/cladding. The study uses ABAQUS finite element software to simulate the thermal behavior of the dual-wire SAW cladding process, providing insights into heat distribution, cooling rates, and residual stress patterns that are critical for predicting overlay quality.

Core Technical Points

Dual-Wire Submerged Arc Welding Process

Dual-wire SAW is an advanced variant of conventional single-wire SAW that offers significant advantages for cladding applications:

Higher deposition rate: Two wires deposit material simultaneously, nearly doubling the deposition rate compared to single-wire SAW
Improved bead quality: The interaction between the two arcs produces a more uniform and wider bead
Reduced dilution: The distributed heat input reduces the penetration depth, lowering dilution of the base metal into the overlay
Lower energy input per unit volume: Despite higher total energy, the energy per unit volume of deposited metal is lower, resulting in finer microstructure
Reduced spatter: The flux coverage and dual-arc interaction minimize spatter

Process Parameter	Single-Wire SAW	Dual-Wire SAW
Wire diameter	3.2–4.0 mm	2.0–3.2 mm
Welding current	400–800 A	200–400 A per wire
Arc voltage	30–40 V	25–35 V per wire
Travel speed	200–400 mm/min	300–600 mm/min
Deposition rate	3–6 kg/h	5–12 kg/h
Dilution rate	20–40%	10–25%
Heat input per pass	Higher	Lower per wire

Finite Element Modeling Approach

The ABAQUS simulation of the dual-wire SAW cladding process involves several key modeling considerations:

Heat source model: The heat source for dual-wire SAW is modeled as a dual-ellipsoidal or dual-Gaussian heat source, representing the two arcs. The heat input distribution is characterized by:

Heat source power: Q = η × I × V (where η is arc efficiency, typically 0.7–0.85 for SAW)
Heat source geometry: Ellipsoidal distribution with different front and rear heat concentration
Arc separation: Distance between the two wires (typically 10–30 mm)
Arc lag: Temporal offset between the two arcs (if applicable)

Material properties: Temperature-dependent material properties are essential for accurate simulation:

Thermal conductivity: k(T) — increases with temperature for most steels
Specific heat: c(T) — increases with temperature, with peaks at phase transformation temperatures
Density: ρ(T) — slight decrease with temperature
Emissivity: ε(T) — increases with temperature

Boundary conditions:

Initial temperature: Uniform at 25 °C (or preheat temperature)
Convective heat transfer: h = 10–25 W/(m²·K) for air convection
Radiative heat transfer: εσT⁴ (where σ is Stefan-Boltzmann constant)
Moving heat source: Follows the welding travel path at the specified speed

Simulation Results and Key Findings

The temperature field simulation reveals several critical aspects of the dual-wire SAW cladding process:

Parameter	Typical Value	Engineering Significance
Peak temperature at arc	1,800–2,200 °C	Determines melting and vaporization
Maximum temperature in HAZ	800–1,200 °C	Determines HAZ microstructure and properties
Cooling rate at 800 °C	5–50 °C/s	Determines overlay and HAZ hardness
Peak temperature in base metal (distance from weld)	Decreases exponentially	Determines extent of thermal effects
Thermal cycle time (t8/5)	0.5–5 s	Correlates with grain growth and phase transformation

Thermal Cycling and Residual Stress

The simulation of thermal cycling during multi-pass cladding reveals:

Each subsequent pass re-heats the previous pass, causing thermal cycling that can either beneficially refine the microstructure or detrimentally cause cracking
The peak temperature in previously deposited layers decreases with each subsequent pass
Residual stresses develop due to differential thermal expansion and plastic deformation during cooling
The residual stress distribution is typically compressive near the weld surface and tensile in the HAZ

Process Optimization Based on Simulation

Parameter Optimization

The simulation results guide the optimization of welding parameters for cladding applications:

Arc separation: Optimal separation (15–25 mm) balances bead width and overlap quality
Current balance: Equal current to both wires produces the most uniform bead; slight imbalance can be used to control bead profile
Travel speed: Higher travel speed reduces heat input but may reduce penetration; optimal speed balances deposition rate and quality
Interpass temperature: Controlled by the thermal cycling effect of subsequent passes; simulation helps predict the interpass temperature

Dilution Control

One of the primary advantages of dual-wire SAW for cladding is reduced dilution. The simulation helps quantify:

Dilution decreases with reduced heat input per wire
Dilution decreases with increased travel speed
Dilution decreases with smaller wire diameter
Dilution is affected by the number of passes and the thermal cycling from subsequent passes

Engineering Practice Integration

Application to Bimetal Pressure Vessels

Dual-wire SAW cladding is particularly valuable for the fabrication of bimetal pressure vessels where:

Large surface areas require efficient cladding (high deposition rate)
Low dilution is critical to maintain the corrosion resistance of the overlay layer
Uniform cladding thickness is required for consistent corrosion protection
Cost efficiency is important for large-scale fabrication

The simulation results help optimize the welding sequence for large clad plates and vessels, minimizing distortion and residual stress while maintaining overlay quality.

Quality Control Implications

The temperature field simulation provides insights for quality control:

Cooling rate prediction: Helps predict overlay hardness and microstructure
Cracking risk assessment: Identifies regions of high thermal stress that may be prone to cracking
Residual stress distribution: Guides the selection of post-weld heat treatment parameters
Distortion prediction: Helps design fixtures and welding sequences to minimize distortion

Study Reflections

The use of finite element simulation for welding process analysis represents a significant advancement in engineering practice. The ability to predict temperature fields, cooling rates, and residual stresses before actual welding enables:

Process optimization without extensive trial-and-error experimentation
Prediction of overlay properties based on thermal history
Identification of potential defects before they occur
Reduction of development time and cost for new applications

The dual-wire SAW process, when properly simulated and optimized, offers a compelling solution for large-scale cladding applications where deposition rate and dilution control are critical. The simulation approach also facilitates the transfer of process knowledge from one application to another, reducing the need for extensive requalification.

The key insight is that computational modeling and experimental validation must be used in conjunction. The simulation provides the framework for understanding and optimization, while experimental verification ensures that the model accurately represents reality. The dual-wire SAW process, with its unique heat input characteristics, benefits particularly from simulation-based optimization, as the interaction between the two arcs creates complex thermal patterns that are difficult to predict through empirical methods alone.