Welding of clad platesMuhammed Labeeb

Clad plates

▪ Clad plates are composite material formed by bonding a base or backing material and a clad material

▪ The base material provides sufficient strength and clad material provides corrosion resistance or special properties

▪ For example, a clad steel plate is made by carbon steel or low alloy steel ( backing material ) and stainless steel plate ( cladding material )

▪ The backing provides the strength and impact resistance of high quality carbon and alloyed steel

▪ The corrosion resistance is given by the cladding which is corrosion resistant stainless steel

Clad plates

▪ Generally clad thickness varies from 5 to 40 percent of the backing thickness

▪ There are two types of clad plates

▪ Single clad and double clad plates

Welding of clad steels

▪ The backing side is generally welded by submerged arc (SAW) for the thicker plates, metal active gas (MAG) or shielded manual arc (SMAW) for thinner plates.

▪ The corrosion resistant cladding is generally welded by shielded manual arc welding (SMAW), tungsten inert gas (TIG) or pulsed GMAW which reduce dilution and distortions

▪ The electrode/filler for the backing metal is selected to match the strength of the backing and to meet the impact strength requirements

Edge preparation

Single-V

▪ Approximate dimensions:

α = 60 °

b = 2 mm

▪ Dimension c is governed by the welding process adopted.

Edge preparation

Single-U

▪ Approximate dimensions:

β = 10 °

b = 2 mm

γ = 4 mm

▪ Dimension c is governed by the welding process adopted.

Recommended weld sequence

STEP 1

▪ Weld the Backing Metal with a suitable filler material. When welding the root, avoid melting the cladding metal.

Recommended weld sequence

STEP 2

▪ Weld the sealing run either with the filler material adopted for the Backing Metal or with a suitable high alloy grade material compatible with the Cladding Metal .

Recommended weld sequence

STEP 3

▪ The Cladding Metal shall be welded with filler of like kind or higher alloyed. The criterion for the choice of filler metal is that the requirements to be met by the cladding shall also be fulfilled by the weld.

General requirements

▪ Welding process, edge preparation, filler metal, etc, shall be chosen in such a manner that the mechanical properties

▪ When the welded joint is to be heat treated, the effect of the heat treatment on the component metals - backing metal, clad metal and the weld metal-shall be taken into consideration.

▪ Welds shall be made using well established practices.

References

▪ Recommended Practice for Welding of Clad Steels, IS : 9006 – 1978 ( rev 1998), Indian Standards Institution

▪ Forming and Welding Clad Plates - 05.01.2011 Rev 1, Industeel, ArcelorMittal