Studies on 6% Nickel Steel for Low Temperature Uses

Synopsis Studies were made in conllection with the del'elolJlnellt qf a Ilew steel for low-temperature uses. The e.!fects qf aLLoying elements on the toughness q{ 6° 0 N i steel were examined in relation to metallurgical factors such as temper brittleness. microstructure, and the stabitit.)' of temper:{ormed austenite. The results were as foLLows : (/) k fanganese refine., lhe microstructure and ;IIlIHoves toughness but promotes susceptibili!:J' to temper brillieness. (2) The addition q{ molybdenum or tungstell is beneficial in In'eventing teml}er brittleness of 6" oN i steel with a high manganese content and in producing finely dispersed and stable azutenite islands, but haJ the disadvantage qf retarding reco,'e~)' on tempering. (3) The addition o{ chromium is useless. (4) The addition of co/JIJer has ejJecls similar to that q{ manganese. Based on these reslilts, a new steel has been del'etol)ed with 6''.,Ni, I to 2"" Mn and 0.2°o Mo or 0.45""W , which has a good toughness. such as 13 kg-m at 196 C.