Abstract: Theempiricalelectrontheory of solidsand molecules( EET) and theimproved TFDtheory wereapplied tocalculatethe phasestructurefactorsand interfaceconjunction factorsofcom mon alloying elementsin high speed impact resistance ( HSIR) steel. According tothese va lenceelectron structure parametersitis deduced thatthe alloying elements of high propertyHSIRsteelshould be Mn, Cr, Ni and Mo. The microscopicstructure ofthesteel with this compositionisthe mixtureof martensite, bainiteand austeniteafter quenching andlow tem peraturetempering.Itspropertiesare:σb = 1750 MPa,σ0 2 = 1460 MPa,δ5 = 12 7 % , AKV(at 40 ℃, cross direction) = 21J, which exceed the requirement of design. For the thick plateof high property HSIRsteel,itissuggestedto add alittleamountof Cu on thebasisofabovecomposition .

Key words: High speed impact resistancesteel, valenceelectron structure, composition design