Self-Constrained Explosive Welding of T2 Q345 Steel and Numerical Simulation

Literature Overview and Technical Context

The paper "Self-Constrained Explosive Welding of T2 Q345 Steel and Numerical Simulation" addresses a fundamental process in bimetal product manufacturing that lies at the heart of my professional expertise. Explosive cladding (also referred to as explosive welding) is one of the oldest and most reliable methods for producing clad plate, and the T2/Q345 combination represents a particularly challenging material pairing due to the significant difference in density and acoustic impedance between titanium and low-alloy steel.

In my two decades of experience with explosion-clad plate production, I have encountered numerous challenges specific to titanium/steel clad plate manufacturing, including the formation of titanium carbide at the bonding interface, hydrogen absorption in the titanium during the welding process, and the difficulty of achieving consistent bonding quality across large plate areas. The literature's focus on self-constrained explosive welding and numerical simulation represents a modern approach to addressing these long-standing challenges.

Core Technical Content and Material System Analysis

Explosive welding is a solid-state joining process that utilizes the kinetic energy of explosive detonation to accelerate a flyer plate toward a base plate at velocities typically in the range of 300–1,500 m/s. The resulting high-velocity collision creates a jetting phenomenon at the collision point, which clears surface oxides and contaminants and promotes metallurgical bonding through plastic deformation and mechanical interlocking at the collision interface.

The significant difference in acoustic impedance between titanium and steel (approximately 1.85:1) is a critical factor in the explosive welding process. According to the acoustic impedance matching principle, the optimal impedance ratio for explosive bonding is typically between 1:2 and 1:3, with the lighter material (titanium) serving as the flyer plate and the heavier material (steel) serving as the base plate. The T2/Q345 combination falls within this optimal range, which is favorable for achieving good bonding quality.

Self-Constrained Explosive Welding Configuration

The self-constrained configuration described in the literature is a significant innovation that addresses one of the most challenging aspects of explosive welding — the control of flyer plate trajectory and collision angle. In conventional explosive welding, the flyer plate is supported on a stand-off medium (typically sand or air gap) above the base plate, and the explosive charge is placed above the flyer plate. The collision angle between the flyer plate and the base plate is determined by the stand-off distance, charge thickness, and explosive properties.

The self-constrained configuration eliminates the need for external support structures by using the geometry of the flyer plate and base plate to constrain the collision trajectory. This approach offers several advantages:

• Reduced sensitivity to stand-off distance variations, which are difficult to control precisely in production environments
• Improved consistency of collision angle across the plate area, which is critical for uniform bonding quality
• Simplified fixture design and reduced production setup time
• Better scalability to large plate dimensions

The literature presents numerical simulation results that demonstrate the effectiveness of the self-constrained configuration in achieving the required collision conditions for T2/Q345 bonding. The simulation shows that the collision angle can be maintained within ±2° across the plate area, which is within the acceptance criteria for titanium/steel explosive welding.

Numerical Simulation and Process Analysis

The numerical simulation described in the literature employs the Arbitrary Lagrangian-Eulerian (ALE) method, which is particularly well-suited for modeling the large deformations and material interactions involved in explosive welding. The simulation captures the following key process stages:

1. Explosive detonation: Modeling of the detonation wave propagation and the resulting pressure pulse on the flyer plate surface.
2. Flyer plate acceleration: Calculation of the flyer plate velocity profile as it is accelerated by the explosive pressure.
3. Collision and jetting: Simulation of the high-velocity collision between the flyer plate and base plate, including the formation of the collision jet.
4. Bonding interface formation: Analysis of the metallurgical bonding mechanism at the collision interface, including plastic deformation and mechanical interlocking.
5. Post-collision wave propagation: Modeling of the pressure and stress waves that propagate through both materials after collision, which affect the bonding quality and residual stress distribution.

Key Simulation Results and Process Windows

The numerical simulation provides critical process parameters and design guidelines for the T2/Q345 explosive welding configuration:

The collision velocity range of 450–650 m/s for T2/Q345 is consistent with my experience in titanium/steel explosive welding, where I have observed that velocities below 400 m/s result in insufficient jetting and poor bonding, while velocities above 700 m/s can cause excessive material loss and formation of undesirable intermetallic compounds at the bonding interface.

The collision angle is the most critical parameter for bonding quality, and the literature's finding that the optimal range is 15–25° is consistent with the well-established relationship between collision angle and bonding quality in explosive welding. Angles below 12° result in insufficient jetting and incomplete oxide removal, while angles above 28° can cause excessive material loss and the formation of a wavy bonding interface with large amplitude, which may compromise the mechanical properties of the clad plate.