Ananda Sarkar Never attempt welding used high alloy Cr-Ni or Ni-Cr-Fe alloys - especially used tubes with bore carburization. Fundamental requirement for these used (service carburization seen) alloys for good weldability : Bring the alloy to normal supersaturated solid solution-annealed condition before welding with any of these filler wires. For this you have to solution heat treat the parts to be cut , machined to bevel joint design and then only weld using either Inco 617 or Inco 625. Inco 625 should give you good welding if you do this pre solution heat treatement at close to 1160-1200 deg cent and then attempt welding. If you do without that, you will get cracks only. You will not give long service life and your welding will give problems. Trust this is of help to you C.V.Srinivasan Nishi Engineers Pvt Ltd India March 08, 2006 E-mail: nishi@vsnl.com >We have some heavily carburized heater tubes ( 35Cr45Ni). We >are trying to weld them with different fillers/WPS > >1> Root: UTPA 25Cr35Ni > Hotpass : UTPA 35Cr45Ni Crack occured during root. > >2> Root: Inconel 617 > Hotpass : Inconel 617 > >3> Root : Inconel 625 > Hotpass : Inconel 625 > > Can anybody please tell me which will be the best WPS to >follow ? >Which will give the longest life. >What is the differences (metallurgical/mechanical) between >the said fillers ? > >Inspection Engineer >HPL, India >Ananda.Sarkar@hpl.co.in

Thank You Sir for your advice. We have been following a repair welding procedure of buttering and welding with Inco 625 instead of soln anneal treatment as it is very difficult insitu inside the furnace. The results are quite satisfactory. How can we detect microcracks by NDT other than metallography ? Inspection Engineer BE (Metallurgy) ASNT Level II RT,LPT,MPT HPL, India Ananda.Sarkar@hpl.co.in 09232396661