Ferrite testing is considered a form of nondestructive testing.
Ferrite testing is a technique used to measure the delta ferrite content in austenitic stainless steel and duplex stainless steel.
Ferrite test is important as it helps to understand
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If the ferrite content is too low, then the stainless steel may be susceptible to solidification cracking (hot cracking) upon welding.
If the ferrite content is too high, then the risk of corrosion increases.
The mechanical properties of the stainless steel could be negatively affected if the ferrite content is too high.
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The presence of ferrite in the range of 4-8% in austenitic stainless steel welds is ideal.
In duplex stainless steels, 35 to 65% ferrite is preferred, though 50% is optimum. This ensures corrosion resistance, toughness and strength.
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