Dear all We have repaired casting materials(25%Cr.35%Ni.0,1%C), we used SMAW process and many cracks appeared,they are located on the base metal and on the liaison of the weld and the base metal.The % of Nb and the base material is 1,1%. No cracks appears in the welds This material is working since five years The Nb is it the cause of my problem? thank you Azedine

Azedine Repair welding an used five year old centri or static cast 25/35/Nb material - without prior solution anneal treatment is a short term solution to any user. User has to take account the In - service service effect related to creep damages , oxidation & bore carburization for any successful repair weld of high temperature cast HP type alloys. This topic has been raised by different users in the same forum - in the last two years. Request reader to read the replies posted. For a successful lomg term use of a repair welded component of HP /HK/HT type alloys, there is no short term solution other than bringing the base metal and HAZ areas to solid-solution annealed condition. This only will give a near virgin metal composition and strength for use for another couple of years. SMAW weld of a successfuly pre-solution annealed HP/HK/HT alloy with NB can easily be done. This will give near creep strength as that of virgin metal used for centri or static casting of these alloys. We have successfully evolved repair weld approach for successful repair welding for these alloys. Also these repair welded assemblies had lasted nearly another -40,000 to 100,000 hour service life - - before the users decided to discard from other factors - both in steam - naphtha or methnol or hydrogen reformer service and in ethylene cracking services for different user industries. Trust this is of help to you C.V.Srinivasan Nishi Engineers Pvt Ltd India May 30, 2006 E-mail: nishi@vsnl.com >Dear all > >We have repaired casting materials(25%Cr.35%Ni.0,1%C), >we used SMAW process and many cracks appeared,they are >located on the base metal and on the liaison of the weld and >the base metal.The % of Nb and the base material is 1,1%. >No cracks appears in the welds >This material is working since five years > >The Nb is it the cause of my problem? > > >thank you >Azedine