Accession Number : ADA308857

Title :   Comparison of Isothermal Salt Quench and Oil Quench Plus Temper of 4XXX Low Alloy Steels.

Descriptive Note : Final rept.,

Corporate Author : ARMY ARMAMENT RESEARCH DEVELOPMENT AND ENGINEERING CENTER WATERVLIET NY BENET LABS

Personal Author(s) : Farrara, Richard

PDF Url : ADA308857

Report Date : FEB 1996

Pagination or Media Count : 30

Abstract : A comparison is provided of the mechanical properties resulting from heat treating two low alloy steels (AISI 4140 and AISI 4340) by the conventional procedure (austenitize, oil quench, temper) and by an isothermal salt quench (austenitize, hot salt quench). but with no temper procedure. Also, a comparison is provided of the dimensional changes and distortion for both steels heat treated by both procedures. The hardness ranges evaluated are Rc 40/45 and Rc 45/50. The conventional rapid oil quench causes distortion and dimensional change of components, hence components heat treated to those high hardness levels have to be finish machined, typically with grinding tools after heat treatment. The isothermal salt quench is a relatively gentle quench cycle that produces a microstructure (mixture of martensite and lower balnite) known to result in excellent mechanical properties. The small distortion and dimensional changes from this procedure would allow finish machining to be completed prior to the heat treatment. The material would be readily machineable (annealed condition) and the associated reduced amount of fixturing/set-ups would provide economic benefits. The primary purpose of this effort was to compare the mechanical properties that result from the conventional and isothermal salt quench heat-treating procedures. If the properties from the isothermal salt quench are equal to or better than the results from the conventional procedure, the engineering community could allow this cost-saving procedure. The results of this effort indicate that the properties obtained from the isothermal salt quench of AISI 4140 are not equivalent to those obtained from the conventional oil quench-temper. whereas the properties for AISI 4340 from the isothermal salt quench are equivalent or higher than from the conventional oil quench-temper procedure.

Descriptors :   *QUENCHING, *SALTS, *OILS, *TEMPERING, *ISOTHERMS, ANNEALING, MECHANICAL PROPERTIES, MICROSTRUCTURE, ECONOMICS, MACHINING, TOOLS, HIGH TEMPERATURE, COMPARISON, STEEL, MIXTURES, HEAT TREATMENT, BAINITE, DISTORTION, HARDNESS, GRINDING, MARTENSITE, LOW ALLOY STEELS.

Subject Categories : Fabrication Metallurgy
      Inorganic Chemistry
      Mfg & Industrial Eng & Control of Product Sys
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE