STAINLESS STEEL vs CARBON STEEL 1

[foliver]

I need to weld a tunnel thruster (tunnel made of stainless steel) with ship’s structure carbon steel (Lloyd’s Register grade A).

On duty stainless steel, carbon steel and welding will be submersed at sea water.

I would like to get

1.- a good welding
2.- an interface carbon/stainless as free as possible of future corrosion.

Step by step welding procedure will be appreciate (I was told to spent some 309 at the edge of the carbon steel tunnel before welding to increase Cr. content).

F. Oliver.

 

[foliver]

Please do not spent time on my question I found answer myself:

1.- Cover carbon steel to be join with a 25% Cr - 20% Ni welding.

2.- Final welding must be done with 18/8 Cr-Ni.

3.- Preheat 100ºC.

4.- Do not allow steel to reach above 300ºC during welding.

I'll try.

F. Oliver.

 

[Rich2001]

A few words of caution:

Austentic Stainless steel (18/8) have a problem with crevice corrosion. to prove it to yourself: put an 18/8 nut and bolt together and place in sea water, after about 2 weeks take it out. The nut and bolt will look fine on the outside but put a wrench on it it will have corrode from the inside out. Look closely at you design eliminate any crevices.

Also 310 SS (25/20) hot cracks very easily. a would suggest a liquid penentant test (DYE TEST) after buttering the CS with the 310.

GoodLuck, Rich

 

[kicker]

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