HIGH STRENGTH, HIGH TOUGHNESS ROTATING SHAFT MATERIAL

摘要

An age hardenable, martensitic steel alloy that provides high strength, h igh toughness, and good low cycle fatigue life and a method of making same a re disclosed. The alloy comprises a matrix having a weight percent compositi on consisting essentially of about Carbon 0.2-0.36 Manganese 0.20 max. Silic on 0.10 max. Phosphorus 0.01 max. Sulfur 0.004 max. Chromium 1.3-4 Nickel 10 -15 Molybdenum 0.75-2.7 Cobalt 8-22 Aluminum 0.01 max. Titanium 0.02 max. Ca lcium 0.001 max. and the balance being iron and usual impurities. The alloy further contains a plurality of inclusions dispersed in the alloy matrix. Th e inclusions comprise calcium compounds that are about 0.4µm to about 7.0µm in major dimension, they have a median size of at least about 1.6µm in major dimension, and the inclusions contain essentially no rare earth elements.