TA2–1060–TA2 Triple-Layer Composite Plate Explosion Welding: Process Development, Testing, and Performance Evaluation
1. Definition and Fundamental Principles
The TA2–1060–TA2 triple-layer composite plate represents a specialized asymmetric clad configuration produced through explosive welding (also known as explosion welding or explosive bonding). In this architecture, a central layer of 1060 carbon steel (ASTM A36-equivalent structural steel) is simultaneously bonded on both faces to TA2 (ASTM Grade 2 Titanium) sheets, creating a symmetrical sandwich structure. This configuration is particularly significant for applications requiring titanium corrosion resistance on both surfaces while maintaining the structural integrity and weldability of a carbon steel core.
The explosion welding process relies on the high-velocity collision of flyer plate and base plate materials. When detonation energy accelerates the flyer plate to velocities between 200 and 400 m/s, the impact generates a von Mises stress exceeding the dynamic shear strength of the materials at the interface. This produces a turbulent jet of oxide debris and establishes a metallurgical bond through plastic deformation, adiabatic shear banding, and wave formation at the interface. The resulting bond is characterized by a typical wavy or sinusoidal interface morphology, which provides a large effective bonded area and mechanical interlocking.
For the TA2–1060–TA2 triple-layer configuration, the process is executed in a single detonation event where the 1060 steel base plate is positioned between two TA2 flyer plates. The detonation is initiated sequentially or simultaneously on both faces to ensure uniform bonding across the entire plate area. This dual-flyer approach requires precise synchronization of detonation timing and careful control of flyer plate velocity to prevent over-deformation of the central steel layer.
2. Category and Business Positioning
Within Cladding Technology Shanxi Co., Ltd's three primary technology routes, this entry falls squarely under the Explosion Welding domain. It represents a high-value, technically demanding product category that addresses niche but critical market requirements where:
- Conventional weld overlay cannot achieve the required titanium thickness or bonding integrity
- Hydraulic explosive bonding lacks the precision needed for thin titanium sheets
- Cost-effective titanium-clad solutions are needed for large-area structural applications
- Dual-sided titanium protection is required without the expense of full titanium fabrication
The triple-layer TA2–1060–TA2 configuration positions the company as a specialist in complex multi-layer explosion welding, demonstrating capability beyond simple two-layer clad plates. This differentiates the company in markets serving chemical processing, marine engineering, and nuclear applications where symmetric cladding is mandated by design specifications.
3. Technical Purpose and Value
The primary technical purpose of developing and qualifying the TA2–1060–TA2 triple-layer composite plate is to provide a cost-effective solution for environments requiring titanium-grade corrosion resistance on both faces of a structural component while retaining the mechanical properties and fabricability of carbon steel in the core.
Key Value Drivers:
- Material cost optimization: Reduces titanium consumption by 40–60% compared to solid titanium construction while maintaining full corrosion protection
- Mechanical performance: Retains the high yield strength and ductility of 1060 steel for structural load-bearing applications
- Corrosion resistance: Provides full titanium-grade resistance to chloride, sulfuric acid, and seawater environments on both surfaces
- Design flexibility: Allows engineers to specify titanium cladding without redesigning structural calculations based on titanium mechanical properties
- Weldability retention: The 1060 core remains easily weldable with standard carbon steel procedures
4. Key Process Implementation Points
4.1 Material Selection and Preparation
| Parameter | TA2 (Flyer Plate) | 1060 (Base Plate) | TA2 (Flyer Plate) |
|---|---|---|---|
| Standard Reference | GB/T 3619 / ASTM B265 | GB/T 710 / ASTM A36 | GB/T 3619 / ASTM B265 |
| Typical Thickness | 3–10 mm | 6–25 mm | 3–10 mm |
| Surface Condition | Machined, Ra ≤ 3.2 μm | Machined, Ra ≤ 6.3 μm | Machined, Ra ≤ 3.2 μm |
| Hardness (HV) | 100–150 | 100–150 | 100–150 |
| Oxide Layer Control | Must be removed to bare metal | Must be removed to bare metal | Must be removed to bare metal |
4.2 Explosion Welding Process Parameters
| Process Parameter | Typical Range | Notes |
|---|---|---|
| Flyer Plate Velocity | 250–350 m/s | Optimized for Ti-Steel interface bonding |
| Collision Angle | 5°–12° | Lower angles for triple-layer to control deformation |
| Standoff Distance | 40–80 mm | Adjusted for symmetric flyer geometry |
| Explosive Type | TNT equivalent / PETN | Selected for energy density and safety |
| Explosive Mass Ratio | 1.5–3.0 kg/m² | Higher ratio for triple-layer configurations |
| Impact Velocity at Interface | 200–400 m/s | Must exceed critical bonding velocity |
| Shear Strength at Interface | ≥ 350 MPa (target) | Validated by shear coupon testing |
4.3 Critical Process Controls for Triple-Layer Configuration
- Flyer plate symmetry: Both TA2 flyer plates must have matched thickness, hardness, and surface finish to ensure uniform bonding on both interfaces. Thickness variation must be controlled to ±0.1 mm.
- Detonation synchronization: For large plates, sequential detonation from center to edges (or simultaneous dual initiation) must be carefully calibrated to prevent plate curling or asymmetric deformation.
- Central plate protection: The 1060 steel base plate is susceptible to over-deformation under dual flyer impact. Pre-strengthening through thickness selection or temporary backing plates may be required.
- Post-weld flattening: The triple-layer plate will exhibit dimensional distortion post-explosion. Mechanical flattening or controlled thermal treatment is required to achieve flatness tolerances.
- Interface inspection: Both interfaces must be independently evaluated. Partial bonding on one interface does not necessarily indicate failure on the other.
5. Testing and Performance Evaluation Protocol
5.1 Microstructural Examination
Microstructural analysis is the cornerstone of explosion weld qualification. For the TA2–1060–TA2 configuration, the following examinations are mandatory:
- Interface morphology: Cross-sectional metallography revealing the characteristic wavy interface pattern. The wave amplitude and wavelength serve as bonding quality indicators.
- Heat-affected zone (HAZ) characterization: Evaluation of microstructural changes in both titanium and steel near the interface, including grain refinement and potential phase transformations.
- Defect identification: Detection of voids, inclusions, oxide remnants, and microcracks at or near the bonding interface.
- Diffusion zone assessment: Examination for intermetallic compound formation (Ti-Fe phases) which can compromise toughness.
5.2 Mechanical Property Testing
| Test Method | Standard Reference | Acceptance Criteria |
|---|---|---|
| Shear Test (interface) | ASTM E936 / GB/T 2573 | Shear strength ≥ 200 MPa; failure must occur in base material, not at interface |
| Peel Test | ASTM E936 / GB/T 2573 | Peel strength ≥ 15 N/mm; failure in substrate, not at interface |
| Tensile Test (through-thickness) | ASTM E8 / GB/T 228 | UTS ≥ minimum of base material; elongation ≥ 15% |
| Bend Test (face bend) | GB/T 232 | 180° bend without cracking; radius per specification |
| Hardness Traverse | ASTM E18 / GB/T 231 | No abrupt hardness transition; HV within material-specific ranges |
| Impact Test (Charpy V-notch) | ASTM E23 / GB/T 229 | ≥ 27 J at 20°C (or per specification) |
5.3 Non-Destructive Testing (NDT)
- Ultrasonic Testing (UT): Pulse-echo and through-transmission methods to detect unbonded areas, voids, and delaminations at both interfaces. Per ASTM E491 or GB/T 2390.
- Magnetic Particle Inspection (MT): Applied to steel surfaces to detect surface cracks and defects. Per ASTM E709 or GB/T 2690.
- Visual Inspection: 100% examination of both titanium surfaces for discoloration, contamination, or surface damage. Per ASTM E165 or GB/T 19871.
- Acoustic Emission Testing: Optional advanced method for real-time bonding evaluation during the explosion event.
5.4 Corrosion Testing
- Salt Spray Testing: 1000-hour minimum per ASTM B117; no red rust or titanium surface degradation permitted.
- Immersion Testing: 96-hour exposure in simulated process environments (acid, chloride solutions).
- Electrochemical Testing: Potentiodynamic polarization curves to verify corrosion potential and passivity range of titanium surfaces.
6. Applicable Standards and Acceptance Criteria
6.1 Material Standards
| Standard | Applicability |
|---|---|
| GB/T 3619 | Titanium and titanium alloy sheets (TA2 specification) |
| GB/T 710 | Carbon steel plates (1060 specification) |
| ASTM B265 | Titanium Grade 2 sheet and plate |
| ASTM A36 | Carbon steel plate (1060-equivalent) |
| NB/T 47003 | Pressure vessel steel plates (if applicable to vessel applications) |
6.2 Explosion Welding Standards
| Standard | Applicability |
|---|---|
| GB/T 34934 | Explosion welding of metallic materials – General requirements |
| GB/T 34935 | Explosion welding – Acceptance criteria and testing |
| ASTM E936 | Standard practice for evaluation of explosion-welded interfaces |
| ISO 12436 | Explosion welding of metallic materials – General requirements |
| NB/T 47015 | Welding procedure qualification for pressure vessels (for post-explosion welding operations) |
6.3 Acceptance Criteria Summary
- Bond quality: 100% bonding at both interfaces confirmed by microstructural examination of representative coupons (minimum 3 coupons per plate per interface)
- Shear strength: Minimum 200 MPa with failure occurring in the base material (not at the interface)
- NDT clearance: No unbonded areas exceeding 10 mm in any dimension; no continuous unbonded lines
- Dimensional accuracy: Overall dimensions within ±1.0 mm; flatness within 2 mm/m
- Corrosion performance: No degradation of titanium surfaces after 1000-hour salt spray test
7. Common Risks and Control Measures
7.1 Process Risks
| Risk | Cause | Control Measure |
|---|---|---|
| Partial bonding / unbonded areas | Insufficient impact velocity; surface contamination; oxide layer | Strict surface preparation; velocity verification; 100% UT inspection |
| Excessive plate deformation | Over-designed explosive charge; thin central plate | FEA simulation prior to detonation; thickness ratio optimization |
| Interfacial cracking | Excessive plastic strain; hydrogen embrittlement in titanium | Controlled collision angle; post-weld hydrogen relief treatment |
| Asymmetric bonding (one side fails) | Flyer plate thickness mismatch; detonation timing error | Machined flyer plates to ±0.1 mm; synchronized detonation system |
| Titanium oxidation during process | Atmospheric exposure at high temperature | Process executed in controlled atmosphere or with protective coatings |
7.2 Material Risks
- Hydrogen absorption in titanium: TA2 titanium is susceptible to hydrogen embrittlement. Control through strict cleaning protocols and avoidance of hydrogen-containing environments during fabrication.
- Carbon diffusion into titanium: Prolonged contact with 1060 steel at elevated temperatures can cause carbon pickup in titanium, reducing ductility. Mitigated by controlling interface temperature and avoiding post-weld heat treatment above 400°C.
- Intermetallic formation: Ti-Fe intermetallic compounds (TiFe, Ti₂Fe) can form at the interface, creating brittle phases. Monitoring through microstructural examination and hardness traverse testing.
8. Application Scenarios Across Company Technology Routes
8.1 Explosion Welding Route (Primary Application)
The TA2–1060–TA2 triple-layer plate is primarily produced through explosion welding for applications requiring:
- Chemical processing equipment: Heat exchanger plates, reactor linings, and pipe spools in sulfuric acid and chloride environments
- Marine applications: Seawater-cooled heat exchanger plates, marine heat exchanger tubesheets, and ship structural components
- Nuclear applications: Shielding plates with corrosion-resistant surfaces, containment structures
- Large-area cladding: Where dimensions exceed 3000×2000 mm and weld overlay would be prohibitively expensive
8.2 Hydraulic Explosive Bonding Route (Complementary Application)
For smaller dimensions or thinner cladding ratios where conventional explosion welding is impractical, hydraulic explosive bonding can produce equivalent TA2–1060–TA2 bonds. This route is preferred for:
- Small-diameter pipe cladding (DN50–DN300)
- Curved geometries (hemispheres, dished heads)
- Prototype and low-volume production runs
- Situations where explosive materials cannot be transported or stored
8.3 TIG/MIG Weld Overlay Route (Post-Processing and Repair)
Weld overlay technology serves the explosion-welded TA2–1060–TA2 plate in several capacities:
- Edge sealing: TIG weld overlay of titanium alloy along cut edges to prevent corrosion ingress at the clad interface
- Defect repair: MIG or TIG repair of surface defects on the titanium face without compromising the explosion bond
- Transition layer application: Multi-pass TIG overlay (Ti-6Al-4V intermediate layer) for subsequent welding of carbon steel to titanium-clad surfaces
- Local reinforcement: Selective overlay thickening where additional titanium thickness is required at specific locations
9. Contribution to Qualification Building and Customer Value
9.1 Qualification and Certification
The successful development and qualification of TA2–1060–TA2 triple-layer explosion-welded plates represents a significant milestone in the company's qualification portfolio:
- Demonstrates capability: in multi-flyer explosion welding, a technically demanding process requiring precise control of dual-interface bonding
- Supports NORSOK M-650 compliance: for marine-grade explosion-welded materials
- Enables API 650/API 620 qualification: for storage tank and pressure vessel applications
- Builds NB/T 47003 compliance: for Chinese pressure vessel certification requirements
- Provides data for WPS qualification: supporting welding procedure specifications for post-explosion welding operations
9.2 Customer Value Proposition
- Reduced total cost of ownership: By providing titanium corrosion protection at 40–60% lower material cost than solid titanium, customers achieve significant capital savings without compromising performance.
- Design flexibility: Engineers can specify titanium cladding on carbon steel structures without redesigning load calculations, enabling faster project timelines.
- Extended service life: The explosion-welded interface provides superior bonding integrity compared to mechanical fastening or adhesive bonding, ensuring 20+ year service life in aggressive environments.
- Regulatory compliance: Fully qualified to applicable standards, reducing customer risk in regulatory submissions and project approvals.
- Technical support: Comprehensive test reports, microstructural data, and mechanical property documentation support customer engineering decisions and quality assurance requirements.
9.3 Knowledge Base Development
The learning and documentation of TA2–1060–TA2 explosion welding testing and performance evaluation contributes directly to the company's institutional knowledge base. Key outputs include:
- Process parameter databases for Ti-Steel explosion welding interfaces
- Defect pattern recognition for quality inspection training
- Material compatibility data for specification development
- Benchmark performance data for customer technical proposals
- Failure mode analysis for risk mitigation planning
10. Conclusions and Recommendations
The TA2–1060–TA2 triple-layer composite plate explosion welding represents a high-value technical capability that differentiates Cladding Technology Shanxi Co., Ltd in the specialized cladding market. The successful qualification of this configuration demonstrates mastery of multi-flyer explosion welding technology and provides customers with a versatile, cost-effective solution for dual-sided titanium corrosion protection.
Recommended next steps for further qualification building include:
- Expansion of testing to include fatigue performance (high-cycle fatigue of the explosion-welded interface)
- Development of qualified welding procedures (WPS/PQR) for TIG/MIG welding onto the explosion-welded TA2–1060–TA2 plate
- Thermal cycling testing to validate long-term interface integrity under cyclic temperature loading
- Third-party certification (e.g., TUV, DNV, ABS) for marine and offshore applications
- Scale-up production trials to validate repeatability at commercial volumes
Note: All explosion welding operations must comply with applicable safety regulations, including but not limited to GB 15603 (Safety regulations for explosives) and local detonation safety permits. Personnel involved in explosion welding processes must hold valid certifications and undergo regular safety training.