外文翻译-奥氏体不锈钢压力容器的应变强化技术.doc

南华大学机械工程学院毕业设计外文翻译一:Strain Strengthening Technology of Pressure Vessels of Austenitic Stainless SteelDENG Yangchun1, CHEN Gang1, YANG Xiaofeng2, XU Tong3(1EastChina University of Science and Technology, Shanghai,200237, China;2HubeiSpecialEquipmentSafety Inspection and Research Institute, Wuhan,430077, Hubei, China;3China Special Equipment Inspection and Research Institute, Beijing,100013, China )AbstractThe basic principle of strain strengthening was presented, and twomodels of the strain strengtheningOf pressure vessels of austenitic steelthe strain strengthening Avesta model at normal atmospheric temperatures and the strain strengthening Arde form model at low temperatures, were analyzed. Meanwhile, the selections of permissible stress of austenitic stainless steel were compared and analyzed in several pressure vessel standards. EN13445 Pressure VesselStandardchooses1. 0as the yield strength of austenitic stainless steel In this condition, the value of the safe factor of them aterials is low and practicalKeywordsPressure Vessel Austenitic Stainless Steel Strain Strengthening, Yield StrengthArticle Idz: TQ050 4 +1 Document code A Article ID 0254-6094 (2008) 01-0054-06The austenitic stainless steel having good high temperature performance, low temperature performance and corrosion resistance, and high tensile strength, but the yield strength is lower. By the standard of GB150 pressure vessel, material yield strength and tensile strength, respectively, divided by the safety factor to determine the material allowable stress values, whichever is less, often resulting in austenitic stainless steel allowable stress values low, can not give full play to the material carrying capacity. To this end, the researchers by strain hardening improve the yield strength of austenitic stainless steel, his article will make the technology to commentary. 1 Austenitic stainless steel strain hardening basic principlesShown in Figure 1, the deformation of the material exceeds the material yield strength, k reached after unloading is in elastic state, before re-applying a load to the material stress reaches the k, k equivalent material yield strength, apparently k 0 2. Figure 1 austenitic stainless steel unidirectional tensile FigureFor non-stable austenitic stainless steel, due to the strain generated martensite hardening rate gradually increases due to the increase of strain necking was postponed, up to a maximum elongation. In the same time, the martensite the merit-formed so that the stress concentration is relaxed, showing a phase transformation induced phenomena. Processed at room temperature for stable austenitic stainless steel is not formed martensite grain refinement, the lattice distortion and dislocation density will produce a hardening effect.Austenitic stainless steel strain hardening of this feature, widely used in the fields of bridges, buildings, parts of Europe has been used in the field of pressure vessel. Austenitic stainless steel pressure vessel strain hardening commonly used in two modes: the Avesta mode and Arde form mode.2 austenitic stainless steel pressure vessel at room temperature strain hardening - A-Vesta modeThe austenitic stainless steel pressure vessel at room temperature strain to enhance hydrostatic test to produce about 8% (maximum 10%) of plastic deformation, and can improve the yield and tensile strength of the austenitic stainless steel material, the method is usually called Avesta mode (Cold Stretched Forming). The pressure vessel using the media generally liquid nitrogen, liquid oxygen and liquid hydrogen, the main civilian use. Sweden Avesta Sheffield since 1959, has been engaged in the work of the austenitic stainless steel pressure vessel strain hardening, and applied for a patent in many countries 1. Avesta Sheffield in Sweden in 1959 by special permission, after 15 years of use of austenitic stainless steel strain hardening technology manufacturing pressure vessels, Swedish Pressure Vessel Technical Committee in 1974 austenitic stainless steel pressure vessel strain hardening technology, 1975 into the pressure vessel specific standards - strain hardening Pressure Vessel Code 2 (the Cold-stretching Direction - CSD). In 1977, Sweden, Finland, Norway, Germany, Australia, the Netherlands, the United Kingdom, Spain, Portugal, Czechoslovakia and South Africa and other countries have accepted austenitic stainless steel pressure vessel strain hardening technology 3. The Swedish strain hardening pressure vessel standards CSD, use of materials equivalent to 304 and 316L, the maximum thickness of 30 mm, maximum operating temperature of 400 C. Annealed materials 0 2 to about 210MPa, elongation greater than 35%. The enhanced yield strength about 410MPa, conventional methods of design as a new material, and then take k. Strain hardening hydraulic test pressure is determined by the following formula The Swedish CSD standards that uniaxial tensile specimens, up to 10% strain sufficient to ensure that the material yield strength k value. Plane stress Mises yield criterion, the corresponding strain according to Table 1 the ratio between the calculated.Table 1 stress, strain ratio between The Swedish CSD standard that ensure that new material yield strength k value, the cylindrical ring to the maximum strain is 8.7%; the Spherical maximum strain of 5.0%. The Swedish standard specifies a maximum strain of 10.0%. The actual cylinder maximum strain of 3% to 5%, mainly due to: a. Actual material s larger than the standard value; b actual thickness deviation and calculations rounded margin; c head, receivership strengthen effect. Another important problem is that the 1991 edition of the Swedish CSD standard no longer need to ensure that the new material yield strength k value, simply press the strain hardening k calculate the required pressure hydrostatic testing can be. Abandon the 1975 edition of k computing, the need to ensure the requirements of the minimum strain.The jonson J 1 pointed out that the strain hardening need to ensure the stability of the material organization, not because of the strain have martensite. Commonly stable and metastable austenitic small amount of strain conditions, does not produce martensite. 304L and 316 through 300 to 350 C, 000h aging tests showed that the strain hardening processing materials with no strain hardening material handling, small changes in yield strength and tensile strength values, can improve the use of strain hardening temperature. Strain hardening treatment material 550 to 650 C is still very good creep resistance, fatigue strength. Less than 10% strain hardening material, in a weak oxidizing media such as H2SO4, corrosive and strain hardening material; stress corrosion results. , 304L, 316 steel residual stress due to strain hardening to reduce or eliminate this stress corrosion tests confirmed.HesslingG 4 noted that the strain hardening material savings, with increasing temperature, the amount of material savings reduce BrautigamM 5 noted that the base material and the electrode of the pressure vessel with a stable austenitic stainless steel 304LN, when the strain hardening plasticity variable 20 % when used in liquid nitrogen (including enhanced), none of the base metal, weld and heat affected zone to produce martensite. 321 metastable austenitic 20% strain was generated martensite; liquid helium cryogenic, unfinished martensitic transformation; in 20 C, 250 cycles can accelerate the martensitic transformation, consider -196 C, the cycle of martensitic transformation. 20% strain on the stability of austenitic and the metastable austenitic material impact toughness are affected; does not produce martensite stable austenitic material Impact Toughness distorted crystal structure. Stable austenitic materials, 20% strain result in a material impact greater than the low temperature impact toughness decreases stable the austenitic and metastable austenitic materials; 20% strain at 20, -196, -269 , the impact toughness AD can meet the specifications and ASME Code pressure vessel strain; actual strain hardening only 8% to 10%, in the cryogenic liquid enough impact toughness. Ambrose S 6 1969 strain strengthen technological research, first enacted in 1969 the specification ME/1/69-134 strain hardening pressure vessel (for low temperature), 1999, included in the standard AS1210 Appendix 2. Material 304,316 L, etc.; strain limit of 5%, 10% of the local maximum, than Swedish standard conservative. Limit of 5%, mainly in order to meet the requirements of the the ISO/TC11 (1970). Strain hardening method has three advantages: a. The release of residual stress; B. In many cases, changing the shape, improve the anti-yielding capacity; c improve the fatigue performance. The standard EN13458 EU cryogenic pressure vessel Appendix C 7 strain hardening technology, recommended several materials can also use other stable austenite and metastable austenitic material, provided that they meet the technical requirements. Material maximum thickness of 30mm, the maximum temperature of 50 C, elongation greater than 35%. The annealed material strain hardening, the yield strength k than 0 2 increased up to about 200MPa. Design as a new material, and then the conventional method. Strain hardening required hydrostatic test pressure of 1.5 times the design pressure to ensure that in the course of container in the elastic state. The strengthening of the annealed container, the amount of deformation; materials to strengthen the container the (inadvertently reinforce or plate rolling intends to strengthen) refers to the process, the water pressure smaller deformation. Annealed container the maximum allowable 10% strain in a long time to keep the load in the case of allowable increase of 1% to 2% strain, in fact, generally cylindrical to 3% 5% strain. This strain hardening of the material after to maintain a higher elongation and impact toughness. Rana M D 8 of ISO/TC220 2000 on the low-temperature austenitic stainless steel containers, also accept strain hardening method, consistent with EN13458.3 austenitic stainless steel pressure vessel at low temperature strain strengthen-Arde form modeIn 1961, Arde-Portland annealed 301 austenitic stainless steel container? 196 C (liquid nitrogen) insulation, strain hardening hydraulic test, resulting in about 10% (maximum 13%) plastic deformation 301 steel yield and tensile strength, some then after 427 C, and 20h aging treatment, to further improve the yield and tensile strength of 301 steel 9, usually known as the method for Arde form mode (Cryogenic Stretch Forming). The austenitic stainless steel pressure vessels used in the aerospace field, the use of media for liquid nitrogen, liquid oxygen and liquid hydrogen. Of Arde-Portland company Alper RH 10 for a more detailed experimental study of Arde-form mode performance. Ball of the same size (301 steel),? 196 C after strain hardening, without aging treatment at room temperature for more than 2h? 196 C blasting, the yield stress ratio strain enhanced stress a small amount of the increase, indicating that at room temperature under certain aging effect; After 427 C, 20h aging treatment, yield stress ratio strain enhanced stress were significantly increased, and with a different strain hardening stress; stress closer to both blast. Annealed spherical? 196 C Blow, yield stress equivalent to the yield stress of the material at this temperature, which is generated starting strain hardening stress; blasting lower stress, but considering the material is thinned, according to the true stress calculation, blasting stress and strain hardening ball stress more consistent. The blasting experiments conducted at ambient temperature, not after the aging treatment the ball vary depending on the yield stress ball original strain hardening stress; higher yield stress after the aging treatment of the ball, and also higher rupture stress. At the same time, the use of smooth specimens subjected to a tensile test (uniaxial stress),? 196 C, with the strain to enhance stress increases, the room temperature tensile yield strength and tensile strength are increased; samples after aging treatment than without aging The treated samples have a higher yield strength and tensile strength. In order to study the biaxial stress, with notched specimens for tensile test at? 196 C, with the strain strengthen the stress increases, little change in the yield stress of aging sample; without aging treatment increased the yield stress of the specimen; Not after aging the yield stress of the treated samples than the original strengthen stress increases, further strengthening effect at room temperature. ? 196 C to a tensile test, notched specimen, and the tensile strength ratio smooth, without aging the sample, with the original strengthen the stress increases; However, after aging the sample, with the original strengthen when the stress increases. That is, the stress increases with the original strengthen the notch sensitivity increase. Test summary, the following conclusions: a low temperature can be used to strengthen to improve the strength, the manufacture of pressure vessels; b without limitation of strain hardening stainless steel? 196 C have a higher notch toughness; c strengthen the limitation of strain stainless steel,? 196 C and has high strength at room temperature; d in? 196 C generating strain hardening, requires a certain amount of stress. Arde-Portland Henderson SW 11: strain hardening and then after aging can improve strength; improve the material strain hardening creep resistance and notched strength; without the limitation of strain hardening stainless steel, high temperature performance is also good. Below the yield stress, in a strongly oxidizing environment, corrosion resistance and annealed pressure vessel. Summary of strain hardening main advantages: high strength; high creep strength; high notch toughness; distorted low temperature aging at 427 ; improve reliability, the the cylinder deformation of 12% to 14%, the ball deformation of 7% to 8%, testable ray undiscovered defects; reduce stress concentration; for the benefit of the weld, the weld and base metal; improve corrosion resistance.ArdePortland Arthur C 12 pointed out that, Arde form mode manufacturing pressure vessels mainly due to the non-proliferation of type face-centered cubic lattice into a body-centered cubic lattice, austenite into martensite, and after the aging , to further enhance its strength at room temperature. Its successful application in that three important factors: a chemical composition, the material has the best combination of strength and toughness, ease of welding; b welding will produce a contraction of 1%, strain hardening, and the strength of the base metal, It is essential that the welds smooth transition, these can not be achieved by the traditional method; deformation (c design, pressure vessel deformation amount of theoretical calculations mentioned earlier, this is completely unnecessary, pressure vessel deformation simply to or greater than the amount of deformation of the theoretical calculation of the pressure vessel can be). Also, strain hardening, the container to the most natural geometry changes, such as head shape to spherical.4 two austenitic stainless steel pressure vessel strain hardening modeTable 2 Comparison of two austenitic stainless steel strain hardening mode. Relatively, Arde form mode strain greater degree of enhancement, the adverse impact on the material properties are also relatively large, its high cost, the process is more complex, mainly for the aerospace field 13, few reports. Avesta method has been accepted in many European countries, EN13458 Appendix C has been adopted, with more experience.Table 2 austenitic stainless steel pressure vessel strain hardening Comparison5 types of pressure vessel standard austenitic stainless steel allowable stress value comparisonAustenitic stainless steel pressure vessel strain hardening upon the conventional approach to design, manufacturing process and select the material allowable stress values. Austenitic stainless steel pressure vessel unique strain hardening is to increase the allowable stress value and improve the sharpest increase the pressure vessel material yield strength. And the other to improve the austenitic stainless steel material allowable stress value is the yield strength to select and adjust the yield factor of safety, the material is not plastically deformed. United States ASME -1 and ASME VIII -2 required for the austenitic stainless steel materials, allowable stress values to allow a small amount of pressure vessel deformation occasions, the highest desirable design temperature 0 90 2 to it than 0 2/ns. Germany for austenitic stainless steel, the yield strength has value by 1. 0,. Usually, 1 than 0 2 high-40MPa, such as 304, the material will increase the yield strength value of 20%. 50 to 60 years in the last century the United Kingdom, Norway, Sweden, Australia and many other countries. EU EN13445 Pressure Vessel Code also used this approach. Of Pressure Vessel Code for austenitic stainless steel, conventional design standards GB150 and stress analysis and design standard JB4732 at temperatures greater than 100 C, Xu with stress value value with the U.S. ASME -1 and ASME -2 basically the same; lower than 100 C, austenitic stainless steel material allowable stress value varies with carbon steel allowable stress value value the same way. Due to the lower yield strength of austenitic stainless steel materials, the allowable stress values by the yield streng