Triplate Transition Joint

A transition joint that is homogeneously bonded together by vacuum-explosion welding and is often used in shipbuilding for welding an aluminium superstructure to a steel hull.

Triplate® consists of three metals with a steel base material, a corrosion resistant aluminium alloy as the upper layer and, to promote bonding, pure aluminium as the intermediate layer.

The explosive cladding/welding process produces a perfect metallurgical bond which is stronger, more secure and more durable than traditional rivets & welding. Due to its superior bend radii and flexibility more complex profiles can be produced with Triplate®.

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Size & Range

00036 Triplate sample
Dimension Value

Standard strip width

Variable

Standard strip length

max 3800mm

Standard strip thickness - steel

15 or 18mm

Standard strip thickness - aluminium

12 or 16mm

Standard strip thickness - total

27 or 34mm

Range

Size (mm) Comments

3800 x 16 x 34

Triplate meets MIL-J-24445A and is approved by Lloyd’s Register of Shipping.

3800 x 20 x 34

3.1 certification supplied unless requested otherwise.

3800 x 25 x 34

3.2 Lloyds available upon request at time of production.

3800 x 30 x 27

Whilst similar products are manufactured by explosive welding in atmospheric conditions, the unique shockwave process produces superior results as shown below.

Atmospheric vs Vacuum Cladding

Atmospheric Vaccum

Coarse oxide agglomerations with porosity at the steel aluminium interface.

100% dense, homogenous joint.

Oxide agglomerations & porosity initiate fracture.

Does not apply.

Oxide agglomerations & porosity can cause corrosion, in spite of protective coatings.

Does not apply.

Bending of aluminium-steel strips can be difficult due to the coarser bond structure.

Very good formability due to ductile aluminium-steel joint.

Production control is limited by variable weather conditions.

Optimal process control due to constantly reproducible vacuum conditions.

Aluminium-steel joint is hard, making sawing & forming difficult.

Easy sawing & forming due to ductile aluminium-steel joint.

Properties

Mechanical Properties

Property Value

Shear strength – Basemetal/Intelayer

>55N/mm2

Tensile strength (through thickness)

75N/mm2

Processing temperature

max 315oC

Bend test base material in compression

Acceptable

Bend test base material in tension

Acceptable

Side Bend Test

Acceptable

Chemical Composition

Layer Material

Base material

Steel LRS Ship-Plate Grade A or St 52-/3N

Interlayer

99.5% pure aluminium - Alloy 1050A

Superlayer

Aluminium alloy 5083 (AlMg4.5Mn)

Processing

  • During processing the temperature of the material MUST NOT be allowed to exceed 315<sup>o</sup>C.
  • DO NOT pre-heat the transition joint before welding.
  • Welding methods to be used are similar to those for the parent metals.
  • Ideally the aluminium weld should be made first after removal of the aluminium oxide film by wire-brushing, followed by de-greasing. Argon shielding gas is recommended. Small diameter wires are recommended (1.2mm). Welding methods include GTAW, GMAW, TIG, MIG and Synergic pulse MIG.
  • The steel weld is made using a coated electrode and GMAW, SMAW or FCAW. Small diameter electrodes are recommended (2.5mm).
  • When bending ensure that the minimum bend radius is at least ten times the strip width or thickness.

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