简介:Recentinvestigationsindicatedthatmetalscanbeeffectivelystrengthenedbynumeroustwinboundaries(TBs)withtwin/matrixlamellarthicknessesinthenanometerregime.Superiorstrength-ductilitysynergieshavebeenachievedwiththenano-twinstrengtheningmechanism.Inthistalk,thenovelnano-twinstrengtheningwillbeappliedtoaustenitesteelsincluding316LstainlesssteelandaFe-Mnsteelinordertooptimizetheirstrength-ductilitycombinations.Thesteelsareprocessedbymeansofdynamicplasticdeformation(DPD,i.e.,plasticdeformationathighstrainrates).Single-phased(austenite)bulknanostructuredsteelspecimenswereprepared,consistingofnano-sizedgrainsembeddedwithnano-scaletwinbundles.Theas-preparednanostructuredsampleswereannealedatvariousconditions,resultinginpartialrecrystallizationofthenanostructuresandformingamixturestructureofcoarse-grainsembeddedwithnano-twinbundles.Strengthandductilityoftheaustenitesteelswithdifferentamountofnano-twinbundlesareanalyzed.Measurementsshowedthenano-twinstrengthenaustenitesteelscanbesuperstrong(withyieldstrengthabove1GPa)togetherwithaconsiderableductility(elongation-to-failure>20%).
简介:ThermalsimulationtestswereconductedatdifferentdeformationtemperaturesanddegreesbyaGleeblesimulator.Theresultsshowthatthealloyhashigherresistancetodeformation;withanincreaseofthedeformationtemperature,thealloy'sflowstressandmaximumvaluedecrease;withanincreaseofthedeformationdegree,boththeinitialrecrystallizationtemperatureandthecompleterecrystallizationtemperaturedecreasesharply.Whenthedeformationdegreereaches30%,60%and80%,theinitialrecrystalliza...
简介:研究了K4169高温合金在各种工艺条件下及向熔体中加入复合细化剂时的晶粒组织.结果表明.降低浇注温度和加入复合细化剂可以明显细化冷凝后基体的晶粒和提高铸件断面等轴晶的比例。在通常的浇注温度1400℃下加入复合细化济.对合金熔体进行或不进行过热处理时.可使圆柱锭的品粒分别细化至ASTM11.7级和ASTM3.2级:断面等轴晶的比例分别达96%和99%以上.当浇注温度为1420℃,加入复合细化利并对合金熔体进行过热处理时,可使圆住锭晶粒细化至ASTMM10.5级,断面等轴晶的比例达90%以上,提出了晶粒细化的机理并对晶粒细化后断面等轴晶比例增大的现象进行了分析。