New Stainless Steels and Their Welding Technology

摘要

The purpose of the investigation was to develop welding techniques for EP410, EP222, and EI878 stainless steels for use in thin sections. These recently developed alloys are of the maraging type. Samples were cut from plates, welded, and then heat treated. After quenching from 1075-1100 degrees C, EI878 and EP222 steels have an ultimate strength of 70-75 kg/mm (Superscript 2) and a relative elongation of 40 percent (EI878) and 25 percent (EP222). Aging raises the strength to a level of about 100 kg/mm (Superscript 2). All the steels were automatically welded in the as-received condition by using an ADSV-2 machine with a tungsten electrode of 2.5-3 mm diameter. The argon flow rate used was 15-25 1/min. Welding was done with and without a filler wire, which was EP400 (04Kh19N11M3) steel. Welding conditions for these steels are presented. Some samples of EP410 steel were heat treated after welding by tempering either at 625 degrees C for 3 hr or at 425 degrees C for 1 hr, and by quenching from 950 degrees C and then tempering at 425 degrees C for 1 hr. Mechanical properties at plus 20 degrees C and minus 196 degrees C are presented for as-welded samples, with and without heat treatment. Most of the fractures occurred in the base metal. Microstructures and macrostructures of the welded and heat-affected zones are shown. The fusion zone is outlined showing a gradual transition region. (Author)