Debasis Mitra Weldability of service aged WYE Fittings H 46 M with parent metal of Cr39W will be dramatically improved if you solution heat treat both the parts to be welded. Service aged components of corrosion / heat resistant components like these alloys undergo permanent metallurgical transformations which are irreversible. Added to that, elements such as W or micro alloys give additional strength to these cast alloys at 800-950 deg centigrade for getting higher creep strength. In other words these elements give or add additional strength by intermetallic precipitates which are also permanent transformation. These make the repair welding a much more difficult (you should reognize this while attempting repair welding on such heat resistant cast high alloys). For less crack sensitive performance: Inco 625 filler wire would be better than Inco 617. Inco 617 with higher 8-10 Co will add additional creep strength but it will compound or make more difficult welding problems with micro-cracks developing during repair welding of these alloys. Prior to welding: Solution heat treat both the parent and Wye piece to bring to normal super-saturated solution from these service aged permanent metallurgical transformed with intermetallic precipitates high alloys. If you do not do solution heat treatment and still be able to make a successful weld, micro cracks not detected during N.D.T of the weld will develop into major service related crack later in service within a short time - say from six months to one year time. Pre heat : 250 deg cent is a " must" after edge preparation. Choose : "J" bevel may give less heat inpurt and chances of less micro crack due to reduced heat input in "J" bevel design. Check the original weld design before adopting this "J" bevel design for welding. Maintain pre-heat at 350-400 deg centirgrade. If difficult to do maintain pre-heat after first and second run , maintain at a lower temperature of 250 deg cent. Post weld heat : Not needed unless the materials had seen SCC (Stress Corrosion Cracking trend) Use : Inco 625 Filler wire - GTAW Process for buttessing, first run and cover runs. Fro cover runs use - SMAW Process - 3.15 or 4 mm Electrode with reverse polarity. If you lack experience and apprehend any problem to do welding, consult an expert on this before you try on your own. Once you have made a mess of welding on your own trials and multi - stress relateld cracks develop, it will make the job difficult to carry good welding even if you call an external consultant at that time. You should be cognizant of difficulty in welding of service aged centri or static cast high alloy materials that undergo irreversible metallurical transfortmations during service. Reversing the transformations is not possible. Welding as such will make the job more difficult for you to retrct later. Trust this will help you to solve the welding problem. Chakravarthi V Srinivasan Nishi Engineers Pvt Ltd Oct 17 E-mail: nishi@vsnl.com/nishi@hathway.com >W.r.t. weldability, less crack sensitivity performance to >weld build up/ buttering on a service aged ( but not >carburised) WYE Fittings of H46M grade (35Cr-45Ni-0.4C-Nb >microalloyed) which one is more preferred ?? INCONEL 625 >or INCONEL 617 GTAW Filler ??? > >Pl. explain with validations ? I will be grateful for any >welding tips w.r.t. preheat, preheat maintenance, postheat >maintenance etc. to creat a crack free buttering layer/ >build up. > >D.Mitra >Sr. Inspection Engineer / HALDIA PETROCHEMICALS LIMITED/ >West Bengal / INDIA