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Volume 06 - Welding, Brazing and Soldering Part 6

Tham khảo tài liệu 'volume 06 - welding, brazing and soldering part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | been qualified to rigid nuclear code requirements. As-welded electroslag welds in austenitic stainless steels were foi be insensitive to knife-line attack after sensitization for 1 to 5000 h at temperatures ranging from 450 to 750 84 1382 F in tests Ref 48 . It has also been demonstrated that ESW is suitable for welding 25 mm 1 in. thick alloy I plates and 25 mm 1 in. and 114 mr2 4i. thick plates of alloy 800. Matching filler metals and Inconel filler-metal 82 produced sound welds with excellent elevated-temperature strength and stress-rupture results. Because stainless stf nickel-base alloys do not undergo allotropic transformations electroslag welds do not require a high-temperi postweld heat treatment. Aluminum. Both ESW and EGW have been used to join thick sections of aluminum. One such application is to join mm 9.5 in. thick electrical conductors busbars . Instead of the typical copper shoes graphite shoes are used to satisfactory weld surfaces and edge penetration Ref 49 . GagbiộReí 50 reported erratic penetration encountered in ESW of thick-section aluminum due to the magnetic fields generated by the welding process which required sp shielding screens around the weld zone. The high conductivity of aluminum and the prompt formation of a refrac oxide are also of concern. High-fluoride-content fluxes and an inert gas shield in EGW typically produce good resut welding thick-section aluminum. For ESW of aluminum containing 4.5 wt Mg the following flux has been sugges- Ref 51 CONSTITUENT CONTENT WT mgf2 1-30 mgcl2 5-60 LIF 5-60 KCL 5-6 As welding progresses additions are made to the flux containing 30 wt each of KCI LiF arid àrtiộCI0 wt MgF2. This flux is reported to work well for ESW of aluminum with copper shoes Ref 51 . Titanium. The reactivity of titanium requires that residual elements such as hydrogen oxygen and nitrogen minimized in ESW. A slag bath high in halides and containing virtually no oxides and an inert gas argon shield ovei bath are required. .