IRON-BASE ALLOY HAVING HIGH RELIABILITY IN FATIGUE STRENGTH AND ITS PRODUCTION

• Main Authors: OTSUKA KIMITERU, SUENAGA MAKOTO
• Format: Patent
• Language: English
• Published: 24.02.1992
• Subjects: ALLOYS; CHEMISTRY; FERROUS OR NON-FERROUS ALLOYS; FORGE FURNACES; FORGING; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; HAMMERING; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVINGMATERIAL; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; PERFORMING OPERATIONS; PRESSING METAL; PUNCHING METAL; RIVETING; TRANSPORTING; TREATMENT OF ALLOYS OR NON-FERROUS METALS

PURPOSE:To obtain an iron-base alloy having high reliability in fatigue strength by pressing the defects of a graphite-containing iron-base alloy consisting of two-phase mixed structure of bainite and austenite by means of plastic working. CONSTITUTION:A stock of a material consisting of a matrix structure free from primary cementite in a cast state and spheroidal graphite is cast, and a part or the whole of the surface of the resulting cast stock is removed by means of machining. Subsequently, this stock is subjected, without temporary cooling, to heating up to a temp. (about 900-1000 deg.C) at which plastic working is possible. This heated stock is cooled temporarily, reheated, and subjected to rolling and/or forging so that the plastic flow direction of the material and the direction of the principal stress applied to the product become parallel with each other as far as possible. The resulting plastic worked material is cooled temporarily and reheated to undergo austempering treatment, and shot peening is applied to the surface of the treated material. By this method, the iron-base alloy having superior fatigue strength, reduced in the dispersion of this fatigue strength, and having high reliability can be obtained.