Abstract：Tensile test was conducted on 2.25Cr-1Mo steel specimens that were electrochemically hydrogen charged and acoustic emission signals were collected in the real-time stretching process. The results show that tensile strength of 2.25Cr-1Mo steel with hydrogen charging is 536.30MPa, decreased by approximately 57MPa and reduction of area is 43.62%, decreased by 7%, compared with the specimens without hydrogen charging. Hydrogen embrittlement-induced regions known as "fisheyes" and quasi-cleavage morphology are observed on the tensile fracture surface. The AE signals activity in the elastic stage of hydrogen charged 2.25Cr-1Mo steel is enhanced, but the acoustic emission signals activity in the yield stage is decreased. The cumulative absolute energy of AE signals of hydrogen charged specimens during deformation is almost one order magnitude lower than that without hydrogen charged specimens. The AE signals amplitude generated by the hydrogen charged specimens is about 0.33mV lower than that of the specimens without hydrogen charging during tensile deformation, and that the bandwidth of signal is reduced by 0.06MHz. Though the analysis of AE signals, it is found that tensile deformation microscopic mechanism of hydrogen charged specimens is that dislocation emission and motion is enhanced but dislocation cross-slip is inhibited by hydrogen.
 南雲道彦.钢的氢脆的新研究方向[J].金属热处理,2010, 25(3):1-6. NAGUMO M. Turning of the research direction on hydrogenembrittelment of steels[J]. Heat Treatment of Metals,2010,25(3):1-6.
 PHAM T H,SARAZIN-BAUDOUX C,PETIT J,et al.Fatigue crack propagation in gaseous hydrogen environment in low alloy steel[J].Procedia Engineering,2015,114(33):354-360.
 李永德,徐娜,郭卫民,等.高压气相热充氢对SUJ2轴承钢超高周疲劳行为的影响[J].材料工程,2014(2):87-92. LI Y D,XU N,GUO W M, et al. The influence of high pressure thermal hydrogen charging on very high cycle fatigue behavior of SUJ2 bearing steel[J].Journal of Materials Engineering,2014(2):87-92.
 王洁,聂宝华,蔡成,等.加氢反应器环境服役的2.25Cr1Mo钢性能退化研究[J].材料工程,2015,43(1):82-88. WANG J,NIE B H,CAI C,et al. Performance degradation of 2.25Cr1Mo steel serviced in hydrogenation reactor[J]. Journal of Materials Engineering,2015,43(1):82-88.
 ROBERTSON I M. The effect of hydrogen on dislocation dynamics[J].Engineering Fracture Mechanics,1999,64(5):671-692.
 EMERSON E,AVINOGRADOV A,DLMERSON D L. Application of acoustic emission method of hydrogen embrittlement mechanism in the low-carbon steel[J].Journal of Alloys and Compounds,2015,10(1):460-463.
 LYNCH S P. Hydrogen embrittlement(HE)phenomena and mechanism[J].Stress Corrosion Cracking,2012,30(3/4):90-130.
 BAMOUSH A,VEHOFF H. Recent developments in the study of hydrogen embrittlement:hydrogen effect on dislocation nucleation[J]. Acta Materialia,2010,58(16):5274-5285.
 HEIPLE C R,CARPENTER S H. Acoustic emission produced by deformation of metals and alloys.Ⅱ[J].British Medical Journal,1987,6(9):215-237.
 KATO H,TOZAWA T,TAKAYAMA Y. Acoustic emission generated during the tensile testing of AZ31 magnesium alloy[J]. Journal of Japan Institute of Light Metals,1990,40(7):514-519.
 CHOI N S, KIM T W, RHEE K Y. Kaiser effect in acoustic emission from composites during thermal cyclic-loading[J]. NDT & E International,2005,38(4):268-274.
 BELLAHCENE T,CAPELLE J,ABERANE M,et al. Effect of hydrogen on mechanical properties of pipeline API 5L X70 steel[J]. Applied Mechanics & Materials,2011,146(3):213-225.
 LONG Q Y,YIN H. Acoustic emission during deformation of dual-phase steels[J]. Metallurgical and Materials Transactions A,1990,21(1):373-379.
 MUKHOPADHYAY C K,RAY K K,JAYAKUMAR T,et al. Acoustic emission from tensile deformation of un-notched and notched specimens of AlSi type 304 stainless steels[J]. Materials Science & Engineering:A,1998,25(1/2):98-106.
 WANG S,HASHIMOTO N,WANG Y M,et al. Activation volume and density of mobile dislocations in hydrogen-charged iron[J].Acta Materialia,2013,61(13):4734-4742.
 BARNOUSH A,ASGARI M,JOHNSEN R. Resolving the hydrogen effect on dislocation nucleation and mobilety by electrochemical nanoindentation[J]. Acta Materialia,2012,66(6):414-417.
 刘白.氢对位错运动的影响[J].材料科学与工程,2001,19(1):63-66. LIU B. The effects of hydrogen on dislocation[J].Materials Science & Engineering,2001,19(1):63-66.
 NIBUR K A,BAHR D F,SOMERDAY B P,et al. Hydrogen effects on dislocation activity in austenitic stainless steel[J].Acta Materialia,2006,54(10):2677-2684.
 HERMIDA J D,ROVIGLIONE A. Stacking fault energy decrease in austenitic stainless steels induced by hydrogen pairs formation[J]. Scripta Materialia,1998,39(8):1145-1149.
 AUERT I,OIVE J M, SAINTIER N, et al. The effect of internal hydrogen on surface slip localization on polycrystalline AlSi 316L stainless steel[J]. Material Science & Engineering:A,2010,527(21):5858-5866.
 JCM L,PARK C G,OHR S M. Chemical driving force for dislocation motion in hydrogen embrittlement[J]. Scripta Metallurgica,1986,20(3):371-376.