DEVELOPMENT OF IMPROVED METHODS, PROCESSES, AND TECHNIQUES FOR PRODUCING STEEL EXTRUSIONS.

A repetitively producible extruding process has been established for 0.060 inch constant thickness tee sections in high strength steel alloys. With good metallurgical control, warm drawing techniques will further reduce the section to 0.040 inch thickness at 0.003 inch tolerance and an excellent surface finish. However, a differential in extruded sectional thickness in this range complicates metal flow and lubrication considerably. The primary facets controlling success were, in probable order of importance, billet temperature, container temperature, die life, and lubrication. In the case of PH15-7Mo, the key to obtaining crack-free shapes was to maintain a container temperature in the range of 900F. Warm drawing was very beneficial in reducing work hardening and draw load. The means of providing preheat to the section to be drawn left considerable to be desired in that a rather large fluctuation in temperature over the length of the shape was invariably encountered. This was true with the automatically controlled induction heater first utilized and with the resistance heated tubular furnace replacement. The latter functioned dependably, but its fluctuation prevented the use of lubricants with a narrow viscosity range.