毕业论文二 外文文献翻译.doc

学校代码： 10128 学 号： 2011209070aa外文文献翻译 英文题目：Evaluation method of sensitivity of hydrogen embrittlement for high strength bolts题目：高强度螺栓氢脆敏感性评价方法 学生姓名：a 学院: a 专业： 班级： 指导老师： 二零一五年五月十一日Evaluation method of sensitivity of hydrogen embrittlement for high strength boltsAbstract In this study, high strength bolts of 1100 MP a and 1300 MP a grades were charged with hydrogen to measure the sensitivity of hydrogen embrittlement (HE). Different levels of stress conditions based on various tensile stress and strain rates were applied. The bolts were then examined to see whether cracks were formed on the screw threads. The tensile stress and strain rate condition producing the most number of cracks on the screw thread of the bolt was decided as the most suitable test condition for the measurement of sensitivity of HE. For 1100 MP a grade high strength bolts, the most cracks were observed at the tensile stress ratio of 0.85 (load of 80 kN) and strain rate of 1.610E5/s, while for 1300 MP a grades, the most cracks were observed at tensile stress ratio 0.87 (load of 100 kN) and strain rate of1.610E5/s. No cracks were found on the screw threads of bolt when the strain rate was increased over8.310E4/s.1. Introduction It is widely known that as the strength of a bolt increases, it becomes more sensitive to hydrogen related problems, thus limit-ing its application. Mechanical properties, such as a reduction area of ductile fracture, deteriorate drastically when hydrogen is introduced into steel. Especially, the higher the strength of steel,the more likely it is to cause the deterioration of mechanical properties by hydrogen, i.e. delayed fracture by hydrogen embrit-tlement (HE) 1,2. Weld metal and heat-affected zones show clear de gradation of mechanical properties by hydrogen as well 35.There have been many reports on the causes of HE and one of the widely accepted theories is that HE occurs due to an internalaw caused by hydrogen gas pressure. In other words, during metal manufacturing or processing, the over saturated hydro gen in side the bolt is formed in molecular level as microscopic aws applying hydrogen pressure, which in turn, leads to local tri-axial stress state. The movement of dislocations by the stress is then suppressed, weakening ductility, which eventually leads to fracture 69.To date, the sensitivity of HE has been measured by using the following methods. One widely used method is to quantify the hydrogen content using the N.O.H elemental analyzer from a specimen with the size of 555mm 10. The other widely used method is to analyze inter granular fracture pattern by observing the fracto graphy with SEM.However, in case of high-strength plated fasteners, the for me method is all but meaningless as the hydrogen on its surface is lost when the specimen is machined. Observing the fracto graphy also presents difculties in measuring HE sensitivity as it shows brittle fractures by inter granular fracture. Other methods are used to measure the HE sensitivity such as the evaluation of hydrogen delaying fracture method 11 and Thermal Desorption Spectro-metry 12. However, these two methods have an obstacle in adopting them in actual industrial sites as it takes two to three days to complete the measurement.In this study, a new test method is suggested to measure the HE sensitivity by applying tensile loading at a slow strain rate.Fig. 1. Jig for applying constant stress state during hydrogen charging.2.Experimental procedure2.1. Materials The 10.9 grade bolt (10001200 MPa) and 12.0 grade bolt(12001400 MP a) that comply with ISO 898-1 designation 13were used as test samples. The 10.9 grade was hexagon head type bolt (M1280) while the 12.9 grade was a hex socket head cap type bolt (M1280).As shown in Table 1, chemical compositions of the bolts were analyzed by an Inductively Coupled Plasma-Atomic EmissionSpectrometer (Model: LABTAM 8440). This analysis shows that the 10.9 grade was 5120 (boron steel) complying with ASTM A1031 14 while the 12.9 grade bolt was 4135 (SCM 435) complying with ASTM A 519 15.The tensile test of the bolts was conducted by a univer saltesting machine (Model: ZWICK Z 600). Hydrogen pre-chargingA jig shown in Fig. 1 was manufactured to replicate the actual fastening condition used in the industry. The bolts were fast ened at the point of their yield stress by using a digital torque wren ch which is in accord to the general fastening method in the field.Hydrogen charging was done as follows. The bolt specimen and a Cu plated wire mesh were connected into the cathode and the anode, respectively, and 10% H2SO4 mixed with 10 mg/l of As2O3was used as an electrolyte to make the cell as shown in Fig. 2. The current density was held constant by using current power supplier with a digital counter. Table 2 shows electro chemical charging conditions of hydrogen. Cd plating was performed to prevent hydrogen from releasing before HE sensitivity is measured. Table 3 shows the elements and the amount used for Cd plating solution. The bolts were ultra-sonically cleaned and then immersed into a constant currentowing Cd plating solution so that the thickness of Cd was more than 15 m. After tensile test, the fracture surface was observed using a Scanning Electron Microscope (Model: JEOL JSM-6490 LV)to investigate the HE on hydrogen charging bolts. The hydrogen content was measured through Thermal Desorption Spectroscopy(TDS). The heating rate of TDS was xed to 100 K/h while the hydrogen was detected by 5 min interval using a pulse discharge detector (PDD). Fig. 5. Inter granular fracture surface of hydrogen charged 10.9 grade bolt: (a) fractured surface of bolt; (b) A is the surface while B is the middle location of bolt; (c) image of A in (b) showing inter granular fracture and (d) image of B in (b) showing dimple fracture. Fig. 6. Inter granular fracture surface of hydrogen charged 12.9 grade bolt: (a) A is the surface while B is the middle location of bolt; (b) image of A in Fig. 6(a) showing inter granular fracture; (c) magnied image of Fig. 6(b) and (d) image of B in Fig. 6(a) showing dimple fracture.2.3. Observation on sensitivity of hydrogen embrittlement After hydrogen was charged into the bolts at conditions shownin Table 2, the different tensile stress below the yield strength of bolts was applied by a universal testing machine. Different strain rates were applied at constant stress ratio (applied stress/bolttensile strength). In an effort to secure homogeneity of data, a number of 12 bolts were tested at each test condition. To apply accurate levels of stress and to measure precise test speeds, a jig was designed and made as shown in Fig. 3. A dialgauge was attached to each end of the bolt and series of tests were conducted at various displacement speeds to estimate the appro-priate strain rate. After applying the stress at given level, the tensile test was stopped, the bolt was cut in half lengthwise which were then polished for microscopic observation. Within the bolt, an umber of eight screw threads where the stress was intensively concentrated, i.e. upper portion towards the head of bolt, were closely observed to nd any existence of cracks. The stress ratio and the strain rate at which the screw threads with the most number of cracks were selected as the most suitable conditions for conrming the occurrence of HE for each grade bolt.3. Results and discussion Fig. 4 shows the tensile stress at fracture of hydrogen charged bolts. Average of eight tests was conducted for each data point. The10.9 grade bolts fractured at 1041 MPa which was below the yield strength (1076 MPa) while the 12.9 grade bolts fractured at 1240 MPa which was also below the yield strength (1291 MPa). This resultde monstrates that the hydrogen charging was sufcient to cause HE.Fig. 5 depicts the fracture surface of a 10.9 grade bolt that has been charged by sufcient hydrogen. Macroscopic images of fractured bolt and fractured surface are observed in Fig. 5(a) and (b), respectively. The SEM image shows that the outer surface was fractured by inter granular mode as shown in Fig. 5(c) while the core of the bolt was fractured by ductile fracture mode as shown in Fig. 5(d). Fig. 6 shows the fracture surface of a12.9 grade bolt after a tensile fracture test. The fracture mode was similar to the results shown in Fig. 5 of 10.9 grade bolt.The hydrogen contents measured by TDS are shown in Table 4.The 12.9 grade bolts had 23 ppm lower hydrogen content than the 10.9 grade bolts. This result coincides with the study con-ducted by Wang et al. 1 which demonstrated that a bolt with higher strength has lower critical hydrogen content at which the inter granular fracture occurred. Fig. 7 shows the number of threads of 10.9 grade bolts with cracks under different conditions of stress ratio and strain rate related to HE. At the stress ratio of 0.74 (70 kN), no cracks were observed at strain rates above 8.310E5/s, while at strain rate of 1.610E5/s, a number of four threads with cracks were observed. At the stress ratio of 0.85 (80 kN), all threads showed cracks, except for those at the strain rate of 8.310E4/s. At the strain rate of 1.610E5/s, in particular, a number of eight threads showed cracks in 10 bolts out of 12 bolts tested. Only two bolts were fractured under 55 kN and 73 kN during loading even before reaching the target load of 80 kN (stress ratio of 0.85). These results comply with the studies conducted by Ham and Nakamoto 16,17 who showed that as the strain rate is decreased,the HE can be observed readily due to vacancies and clusters(lattice defects) being formed by strain interaction.Figs. 8 and 9 show the cracks observed on the screw threads of10.9 grade bolts that have been transected after applying stress.As shown in Fig. 8, no cracks were found on any of the observed threads at a stress ratio of 0.74 (70 kN), and strain rate of 8.310E5/s. In Fig. 9, all eight threads observed had cracks at the stress ratio of 0.85 (80 kN) and strain rate of 1.610E5/s. Fig. 10 shows the different stress ratios and strain rates appliedon 12.9 grade bolts showing the average number of screw threads with cracks at each condition. No cracks were observed in tested strain rates at stress ratio of 0.84 (97.2 kN). However, at 1.610E5/s, the slowest strain rate, average of two threads, had cracks.In addition, two bolts fractured at 95.3 kN and 96.9 kN during loading.At the stress ratio of 0.87(100 kN), all the strain rates except for8.310E4/s caused cracks. At the strain rate of 1.610E5/s, These results comply with the studies conducted by Ham and Naka moto 16,17 who showed that as the strain rate is decreased,the HE can be observed readily due to vacancies and clusters(lattice defects) being formed by strain interaction.Figs. 8 and 9 show the cracks observed on the screw threads of10.9 grade bolts that have been transected after applying stress.As shown in Fig. 8, no cracks were found on any of the observed hreads at a stress ratio of 0.74 (70 kN), and strain rate of 8.310E5/s. In Fig. 9, all eight threads observed had cracks at the stress ratio of 0.85 (80 kN) and strain rate of 1.610E5/s. Fig. 10 shows the different stress ratios and strain rates applied on 12.9 grade bolts showing the average number of screw threads with cracks at each condition. No cracks were observed in tested strain rates at stress ratio of 0.84 (97.2 kN). However, at 1.610E5/s, the slowest strain rate, average of two threads, had cracks.In addition, two bolts fractured at 95.3 kN and 96.9 kN during loading.At the stress ratio of 0.87(100 kN), all the strain rates except for8.310E4/s caused cracks. At the strain rate of 1.610E5/s,Fig. 7. Diagram showing the number of threads with cracks at various levels of stress ratio and strain rate of 10.9 grade bolt.Fig. 8. Microscopic observation of 10.9 grade bolt screw threads showing no cracks (circled area) after being subjected to tensile condition of strain rate of 8.310E5/s and stress ratio of 0.74.Fig. 9. Microscopic observation of 10.9 grade bolt screw threads showing formation of cracks (indicated by arrow) after being subjected to tensile condition of strain rate of1.6310E5/s and stress ratio of 0.85.Fig. 10. Diagram showing the number of threads with cracks at various levels ofstress ratio and strain rate of 12.9 grade bolt.Fig. 11. Microscopic observation of 12.9 grade bolt screw threads showing no cracks (circled area) after being subjected to tensile condition of strain rate of 8.310E5/s and stress ratio of 0.84.Fig. 12. Microscopic observation of 12.9 grade bolt screw threads showing formation of cracks (indicated by arrow) after being subjected to tensile condition of strain rate of1.6310E5/s and stress ratio of 0.87.4. Conclusion 1.The results of the study suggest a methodology to measure the hydrogen embrittlement sensitivity of high strength bolts of 10.9grade and 12.9 grade, which are as follows:1. The tensile fracture tests of hydrogen charged bolts with 10.9grade and 12.9 grade fractured at 1041 MPa and 1240 MPa,respectively, which were both below its yield strength.2. When different stress ratios and strain rates were applied,the most cracks were found in 10.9 grade bolts at the stress ratio of 0.85 (80 kN) and strain rate of 1.610E5/s condition whereas the most cracks were found in 12.9 grade bolts at stress ratio of 0.87 (100 kN) and strain rate of 1.610E5/s condition.3. Based on this study, the HE sensitivities of high strength bolts of 10.9 and 12.9 grades can be determined by slow strain rate tensile test at given tensile condition as mentioned above.Acknowledgment The present study has been carried out through the nancial support of the Project for the Advancement of Standard Technol-ogy (No. B0012362) by Ministry of Knowledge Economy.References1 M. Wang, E. Akiyama, K. Tsuzaki, Scr. Mater 52 (2005) 403408.2 S. Yamasaki, M. Kubota, T. Tarui, Nippon Steel Tech. Rep. 80 (1999) 5055.3 Y. Kitagawa, K. Ikeuchi, T. Kuroda, Y. Matsushita, K. Suenaga, T. Hidaka,H. Takauchi, J. Mater. Sci. 43 (2008) 1222.4 W. Godoi, N.K. Kuromoto, A.S. Gusimaraes, C.M. Lepienski, Mater. Sci. Eng. A354 (2003) 251256.5 J.S. Seo, H.H. Kim, H.S. Ryoo, Met. Mater. Int. 14 (2008) 515522.6 I.M. Bernstein, A.W. Thompson, Int. Mater. Rev. 21 (1976) 269287.7 H. Shoda, H. Suzuki, K. Takai, Y. Hagihara, ISIJ Int. 50 (2010) 115123.8 K. Takai, H. Shoda, H. Suzuki, M. Nagumo, Acta Mater. 56 (2008) 51585167.9 K. Takasawa, R. Ishigaki, Y. Wada, R. Kayano, ISIJ Int. 50 (2010) 14961502.10 ASTM E1019-11, Standard test methods for determination of carbon, sulfur,nitrogen, and oxygen in steel, iron, nickel, and cobalt alloys by variouscombustion and fusion techniques, Annual Book of ASTM Standards, ASTM,West Conshohocken, 2011.11 ISO 15330:1999(E), FastenersPreloading Test for the Detection of HydrogenEmbrittlementParallel Bearing Surface Method, ISO, Switzerland, 1999.12 ISO 3690:2012(E), Welding and Allied ProcessesDetermination of HydrogenContent in Arc Weld Metal, ISO, Switzerland, 2012.13 ISO 898-1: 2013(E), Mechanical Properties of Fasteners made of Carbon Steeland Alloy SteelPart 1: Bolts, Screws and Studs with Specied PropertyClassesCoarse Thread and Fine Pitch Thread, ISO, Switzerland, 2013.14 ASTM A 1031-05, Standard Specication for Steel, Sheet and Strip, Heavy-Thickness Coils, Alloy, Drawing Steel and Structural Steel, Hot-Rolled, AnnualBook of ASTM Standards, ASTM, West Conshohocken, 2005.15 ASTM A 519-06(2012), Standard Specication for Seamless Carbon and AlloySteel Mechanical Tubing, Annual Book of ASTM Standards, ASTM, WestConshohocken, 2012.16 J.O. Ham, B.G. Kim, S.H. Lee, Kor. J. Met. Mater. 49 (2011) 18.17 T. Nakamoto, H. Suzuki, Y. Hagihara, K. Takai, Materials Science and Technol-ogy (MS&T) 2011, Columbus, Ohio, 2011, pp. 12261233.高强度螺栓氢脆敏感性评价方法摘要 在这项研究中，在1100兆帕，1300兆帕牌号高强度螺栓中充入氢气以测量氢脆（HE）的灵敏度。不同的基于各种拉伸应力和应变速率应力条件级被应用。然后检查螺栓，看看是否裂纹的螺纹形成。拉伸应力和应变速率条件生产最数目在螺栓的螺纹裂纹就被定为最合适的测试条件进行HE的灵敏度的测量。1100 MPa级高强度螺栓，裂缝观察到的0.85（80千牛负荷）和1.6应变率10E-5张/秒的拉伸应力比，而对于1300 MPa一个档次，裂缝进行观察在拉伸应力比0.87（100千牛的负荷）和1.610E-5张/秒的应变速度。没有裂缝螺栓的螺纹发现当应变速率增加超过8.310E-4/秒。1. 简介 众所周知，由于螺栓的强度增加，它增加了氢有关的问题更加敏感，从而限制-制定其下属的应用程序。机械性能，如韧性断裂的还原区，急剧恶化时将氢气引入钢。尤其，较高钢的强度，越有可能是造成机械性能由氢的恶化，即延迟断裂氢脆（HE）1,2。焊缝及热影响区显示的机械性能，通过渐变以及3-5。有已经对HE的原因和被广泛接受的理论之一是，他的发生是由于内部FL许多报道AW引起氢氢气压力。换言之，在金属制造或加工时，过饱和氢形成在分子水平上的螺栓作为微观FL AWS施加氢气压力，这反过来，导致局部三轴应力状态。位错的应力的移动被抑制，弱化延展性，最终导致压裂TURE6-9。为日期，何的敏感性已通过使用以下方法测定。一种广泛使用的方法是从一个标本的555毫米10的大小量化使用NOH元素分析仪中的氢含量。其他广泛使用的方法是通过观察与SEM的断口分析晶断裂模式。然而，在高强度镀紧固件，前者的方法是所有，但无意义作为在其表面上的氢时，检体被加工丢失。观察断口也呈现在测量灵敏度，因为它显示了脆性骨折晶断裂的困难。其他方法可用于测量的HE灵敏度如氢延迟断裂方法评价11和热解吸法12。然而，这两种方法在采用这些在实际工业场所，因为它以完成测量需要两到三天的障碍物。在这项研究中，一个新的测试方法被提出来测量通过施加拉伸载荷以缓慢的应变速率以HE灵敏度。图。1.夹具氢充电过程中施加一定的压力的状态。2. 实验过程 该等级10.9螺栓（1000-1200兆帕）和12.0级螺栓（1200-1400兆帕），其符合ISO898-1指定13作为试验样品。10.9级是六角头螺栓（M1280），而12.9级是一个内六角螺栓型（M1280）。如表1所示，该螺栓的化学成分是由一个电感耦合等离子体原子分析发射光谱仪（型号：8440 LABTAM）。这一分析表明，10.9级为5120（硼钢）以ASTM A103114相符，而12.9级螺栓为4135（SCM435）以ASTM符合阿51915。 （：ZWICK600型号）螺栓的拉伸试验，通过万能试验机进行的。 氢预充电图1所示的夹具。1制造复制在工业中使用的实际的紧固状态。螺栓通过使用一个数字扭矩扳手这是符合在场的一般紧固方法紧固在它们的屈服应力的点。充氢如下进行。螺栓试样安达镀铜丝网被连接到阴极和阳极，分别与10H 2 SO 4与三氧化二砷的10毫克/升的混合物作为电解质，使细胞如示于图2.密度的保鲜举行了利用现有的电力供应商与数字计数器不变。表2示出氢的电化学充电条件。镉镀层进行，以防止氢气HE灵敏度测量前释放。表3示出的元件和用于镉电镀液的量。螺栓被超声波清洁，然后浸入到恒电流佛罗里达州所拖欠镉电镀液，使镉的厚度为人数超过15微米。拉伸试验后，用扫描电子显微镜观察该断裂面（型号：JEOL