We performed welding on a tube sheet of our urea stripper having following material:

CLADDING (10 MM THICK) = ASME SB 265 GR-2
TUBES = ASME SB-338 GR-3

Cracks are observed after welding, my question is:

Is this possible that commercially pure titanium of above grades transforms into martensitic structure? if yes then under what conditions?