Showing papers on "Austempering published in 1976"
1 Jun 1976
TL;DR: In this article, an optimum austemper treatment evolved which resulted in a cast ductile iron which delivered 135 ksi ultimate, 97 ksi yield strength and 11% elongation.
Abstract: : Austempered ductile iron containing nickel was investigated as an economical substitute for alloy steel forgings currently used as critical components in armored vehicles (M113 personnel carrier). An optimum austemper treatment evolved which resulted in a cast ductile iron which delivered 135 ksi ultimate, 97 ksi yield strength and 11% elongation. Low temperature (-40F) impact toughness was 3 ft-lbs and rotational bending fatigue strength was 62.5 ksi at room temperature. A quantity of select components namely, suspension arm, sprocket and track shoe were cast, heat treated and finished machined to demonstrate the applicability of the manufacturing process as well as the service performance of these cast components when subjected to field testing under extreme environmental conditions. (Author)
1 citations
TL;DR: In this paper, the authors show that steel with a structure of upper and lower bainite at 730° for 3 h undergo redistribution of the polygonization type within ferrite needles, with development of a cellular substructure.
Abstract: 1.
Isothermal treatment of steel 12Kh1MF at 350–500°C leads to the formation of a structure consisting of upper and lower bainite. At 500° the structure consists primarily of upper bainite, and at 350° of lower bainite.
2.
With tempering of the steel with a structure of upper and lower bainite at 730° for 3 h the dislocations undergo redistribution of the polygonization type within ferrite needles, with development of a cellular substructure. The acicular structure of the matrix is retained in this case. The density and evenness of the distribution of carbides is higher in upper bainite than in lower bainite.
3.
Steel 12Kh1MF with a structure of upper bainite is more susceptible to recrystallization as compared with a structure of lower bainite, which is responsible for the higher heat resistance of the latter.