EFFECT OF Nb ON DELAYED FRACTURE RESISTANCE OF ULTRAHIGH STRENGTH MARTENSITIC STEELS
Ultra-high strength steels are materials of considerable interest for automotive and structural applications and are increasingly being used in those areas.Higher strength,however,makes steels more prone to hydrogen embrittlement(HE).The effects of Nb and other alloying elements on the hydrogen-induced delayed fracture resistance of cold rolled martensitic steels with ultra-high strength 2000 MPa were studied using an acid immersion test,thermal desorption analysis(TDA)and measuring of permeation.The microstructure was characterized by high resolution field emission Scanning Electron Microscopy(SEM)with Electron Backscattered Diffraction(EBSD)and Transmission Electron Microscopy(TEM).It was shown that the combined addition of Nb significantly improved the delayed fracture resistance of investigated steel.The addition of Nb to alloyed martensitic steels resulted in very apparent grain refinement of the prior austenite grain size.The Nb microalloyed steel contained a lower diffusible hydrogen content during thermal desorption analysis as compared to the base steel and had a higher trapped hydrogen amount after charging.The reason that Nb improved the delayed fracture resistance of steels can be attributed mostly to both hydrogen trapping and grain refinement.
ultra-high strength martensitic steels Nb delayed fracture H embrittlement
Rongjie Song Nina Fonstein Narayan Pottore Hyun Jo Jun Debanshu Bhattacharya Steve Jansto
ArcelorMittal Global R&D,3001 East Columbus Drive,East Chicago,IN,46312,USA CBMM North America,1000 Old Pond Road,Bridgeville,PA,15017,USA
国内会议
杭州
英文
541-547
2015-11-11（万方平台首次上网日期，不代表论文的发表时间）