球墨铸铁在低温及冲击载荷下的韧脆转变行为

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中图分类号：0347.3 国标学科代码：13015 文献标志码：A

Ductile-brittle transition behaviors of nodular cast iron under low temperature and impact loading

ZHANG Yongxin1，FAN Changzeng²， XU Zejian²，QI Kaili’， ZHOU Zhou1

（1.YanqiLake （Beijing）InstituteofBasic Manufacturing TechnologyResearchCo.，Ltd.，Beijing10140o，China;

2.State KeyLaboratoryofExplosion Scienceand SafetyProtection，BeijingInstituteof Technology University， Beijing 100081， China）

Abstract：Tounderstandthedynamic fracture characteristicsof nodular cast iron structures suchasthe spent nuclear fuel storage and transportation vesels under low temperatures and dynamic loads，the mode I dynamic fracture toughness（DFT）of nodular cast iron was tested at different temperatures （20， -40 0 -60 and -80∘C ）using an improved split Hopkinson pressure bartechnique，and focusedon studying the ductile-britle transitionbehaviorof thematerial. Standard thre-point bending specimens with afatigue crack were pre-fabricated before the experiment.A special fixture was used toreplace the transmitter bar，while the temperature wascontroled byaspeciallydesigned environmentalchamber.Thecrack initiation timeof the specime was determined bythestrain gauge method，andthedynamic stressintensity factor （DSIF）atthecrack tip was determinedusing the experimental-numericalmethod.Mesh refinement andelement transition wereusedatthe crack tipregion to ensure a high-accuracyresult of the displacement field.Onthisbasis，the modeIDFTofthe material was finally determined.Theresults showthat under the same impactvelocity，the DFTandthe fracture initiation timeof nodularcast iron decreasesignificantlywith the decrease in temperature.As the temperature decreases，the macroscopic fracture surfaceof nodularcastironchanges fromrough torelativelyflat，indicatingachangeinthefailure modesofthe material.Theeffctof temperatureonthe failure mode is further verifiedbyquantitative microscopic analysis offracturesurfaces.Asthe temperature decreases，the number ofdimples on the fracture surface decreases，while river pattems and cleavage steps increase.It means thattheductilityofeateraliseakeduttebtleessisancdatlowtempeatures.isutilbitltrasiio phenomenon is consistent with the tendency of the measured toughness of the material.

Keywords：nodular cast iron; temperature effect; mode I dynamic fracture toughness; ductile-britle transition

球墨铸铁是一种高强度、高韧性的铸铁材料，而且具有良好的加工性能和耐腐蚀性，因此在一些特殊工业领域常被用作钢材的替代品，如清洁能源储运设备、核乏燃料储运容器、铁路及地铁配件、机车及车辆配件等[1-3]。（剩余12659字）