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 15-7 The molybdenum add- MO Cont'd tive in this alloy causes larger amounts of delta ferrite or free ferrite to form in the weld deposit upon solidification. The amount of ferrite requires some control in order to maintain good ductility in the highest strength conditions.  This con- trol can be accom- plished by the use of filler metal of appro- priate chemical com- position, through heat treatment or both. 17- Martensitic 17-4PH AMS 5825 Not re- Heat treat or Readily weldable using 4PH This alloy AMS 5827 quired. anneal. arc and resistance is Austeni- welding processes itc at elevat- commonly used with ed tempera- Austenitic stainless ture but steels.  Sound welds transforms with properties com- to Marton- parable to parent sitic upon metal can be obtained cooling. using weld metal of same composition and post weld annealing or heat treating.  Spot welding and seam welding readily ac- complished using pro- cedures similar to those used for austenitic stainless. Best results obtained by in partly or fully heated treated condit- ions.  Resistance butt welding not currently recommended. 17- Austenitic 17-7PH AMS 5825 Not re- feat treat or Fusion welding and 7PH in cond- AMS 5827 quired. anneal.  Fusion spot welding can be ition A. 17-4PH welded joints readily accomplished. Heat treat- using 17-4PH Best results are ob- ed condit- electrode can tained by spot welding ion are be heat treated partial or fully heat martensi-- to 170 KSI treated material.  The tic with ultimate ten- surface to be welded some auste- site by aus- should be cleaned by nitic. tenitic condi- vapor or sand to avoid tioning at 1400   porous welds. Inert F followed by gas tungsten are of an- 2-98