Metallurgy Interview Question:

Why duplex or super duplex stainless steels are welded with low heat input type electrode?

Submitted by: Administrator

Duplex and super duplex stainless steel; but in general it's true for welding of all types of austenitic stainless steels -and you must know that we can assume duplex s. steels as austenitic s. steels cause the amount of austenite is 50% of the matrix equal to ferrite- to use a low heat input process. In addition, the reason is general in austenitic s. steels as well. That is because the weld decays. Austenitic s. steels containing about 0.1% carbon or more are often susceptible to inter granular corrosion in the weld HAZ, which is known as "Weld Decay". In these types of S .Steels the higher the heat input, the more severe the weld decay. However, here is a fact that all duplex stainless steels have a carbon content of less than 0.1%. Therefore, the severity of weld decay may be lighter, but still exists, and sensitization takes place more rapidly as the carbon content is increased.
Submitted by: Administrator

because stainless steel retains the amount of heat. means it's thermal conductivity is low.....so sensitisation will occus!!
Submitted by: Kuruva Harish Babu