What filler metal should be used for welding 4130 or 4140 (Chrome Moly)?
Welding of both 4130 or 4140 is complicated and requires the user to develop a procedure based on the application. For an application that is to be heat treated afterwards, use 4130. A preheat is required to control cracking and to reduce hardness in heat affected zone. For up to 1/2″ thick material preheat to a minimum of 400ºF. For 1/2″ – 1″ thick, a minimum of 500ºF. Over 1″ thick will require a minimum of 550ºF. For heat treatment procedures, contact base metal manufacturer for procedure. For an application that will not be heat treated afterwards, use 80S-D2 or 70S-2 depending on application. Consult base metal manufacturer for best option.
