T.O. 1-1A-9 TABLE 2-18.  FUSION WELDING CHARACTERISTICS OF CORROSION RESISTING STEEL - GENERAL(CONT’D) ALLOY/DESIGN RECOMMENDED FILLER MATERIAL/SPEC HEAT TREATMENT REMARKS TYPE STRUCTURE TYPE ELECTRODE ROD PREHEAT POSTHEAT MATERIAL TREAT 420 Martensitic 420 MIL-E-6844 MIL-R-5031 4000 -6000F 1125°-1400 Welding should be 309 Class 2/3 Class 2/3 if possible restricted to elect- 310 before mater- rical method i.e., See Remarks ial has cooled shielded metal arc to 300 F from & tungsten arc, etc. preheat and Oxyacetylene welding welding. should be avoided to prevent carburizing and resulting loss in corrosion resist- ance.  Type 309/310 electrodes can be used if high strength not required. 422 Martensitic 422 For inert 350 -400 F 1200 -1300 F Can be welded by gas method for 8 hours, metal arc or inert air cool. tungsten-arc method. 440 A, B,C & F 440 See Remarks MIL-R-5031 450 F 1300 F for Fusion welding should 309 Class 2/3 4 hours and be accomplished using 310 air cool. electrodes of same composition as parent metal when material is heat-treated after welding.  If a softer weld will meet re- quirements, such as welding for mechani- cal bond only, type 309/310 electrodes can be used. 446 Ferritic 446 300 F 1400 -1450°F Fusion weld using followed by same composition as air cooling/ parent metal.  Weld- water quench. ing of this type is not recommended for applications subject to high impact.  For improvement of ductility in weld area, weld deposit should be preened while at elevated temperature. PH 15-7 PH15- 17-4 AMS AMS 5825 Not re- Heat treat or See 17-7PH except MO (AISI 7MO 5827 PH AMS 5813 quired. anneal. for the following. 632) PH15- 7MO AMS 5812 Inert gas tungsten or 7MO WPH15 fusion welding of VM 7MO annealed and subsequ- VM ently heat treated mat- erial yields a weld of 80-100%.  Resistance flash butt welding is not recommended for joints to use in high strength application. 2-97