期刊文献+
共找到101篇文章
< 1 2 6 >
每页显示 20 50 100
Micro-macro evolution of mechanical behaviors of thermally damaged rock:A state-of-the-art review 被引量:1
1
作者 Yunmin Wang Jun Peng +2 位作者 Linfei Wang Chuanhua Xu Bibo Dai 《Journal of Rock Mechanics and Geotechnical Engineering》 SCIE CSCD 2024年第7期2833-2853,共21页
The influence of thermal damage on macroscopic and microscopic characteristics of different rocks has received much attention in the field of rock engineering.When the rocks are subjected to thermal treatment,the chan... The influence of thermal damage on macroscopic and microscopic characteristics of different rocks has received much attention in the field of rock engineering.When the rocks are subjected to thermal treatment,the change of macroscopic characteristics and evolution of micro-structure would be induced,ultimately resulting in different degrees of thermal damage in rocks.To better understand the thermal damage mechanism of different rocks and its effect on the rock performance,this study reviews a large number of test results of rock specimens experiencing heating and cooling treatment in the laboratory.Firstly,the variations of macroscopic behaviors,including physical parameters,mechanical parameters,thermal conductivity and permeability,are examined.The variations of mechanical parameters with thermal treatment variables(i.e.temperature or the number of thermal cycles)are divided into four types.Secondly,several measuring methods for microstructure,such as polarizing microscopy,fluorescent method,scanning electron microscopy(SEM),X-ray computerized tomography(CT),acoustic emission(AE)and ultrasonic technique,are introduced.Furthermore,the effect of thermal damage on the mechanical parameters of rocks in response to different thermal treatments,involving temperature magnitude,cooling method and thermal cycle,are discussed.Finally,the limitations and prospects for the research of rock thermal damage are proposed. 展开更多
关键词 thermal damage Macroscopic characteristics Microstructure evolution Temperature magnitude Cooling method thermal cycle
下载PDF
Performance Evaluation of a Molten Carbonate Fuel Cell-Graphene Thermionic Converter-Thermally Regenerative Electrochemical Cycles Hybrid System
2
作者 HU Yaowen HUANG Yuewu 《Journal of Donghua University(English Edition)》 CAS 2021年第4期359-366,共8页
A combined system model is proposed including a molten carbonate fuel cell(MCFC),a graphene thermionic converter(GTIC)and thermally regenerative electrochemical cycles(TRECs).The expressions for power output,energy ef... A combined system model is proposed including a molten carbonate fuel cell(MCFC),a graphene thermionic converter(GTIC)and thermally regenerative electrochemical cycles(TRECs).The expressions for power output,energy efficiency of the subsystems and the couple system are formulated by considering several irreversible losses.Energy conservation equations between the subsystems are achieved leaned on the first law of thermodynamics.The optimum operating ranges for the combined system are determined compared with the MCFC system.Results reveal that the peak power output density(POD)and the corresponding energy efficiency are 28.22%and 10.76%higher than that of the single MCFC system,respectively.The effects of five designing parameters on the power density and energy efficiency of the MCFC/GTIC/TRECs model are also investigated and discussed. 展开更多
关键词 molten carbonate fuel cell(MCFC) graphene thermionic converter(GTIC) thermally regenerative electrochemical cycle(TREC) hybrid system parameter analysis
下载PDF
Assessment of gas tungsten arc welding thermal cycles on Inconel 718 alloy 被引量:8
3
作者 M.HERNANDEZ R.R.AMBRIZ +3 位作者 R.CORTES C.M.GOMORA G.PLASCENCIA D.JARAMILLO 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2019年第3期579-587,共9页
Heat moving source models along with transient heat analysis by finite element method were used to determine weld thermal cycles and isothermal sections obtained from the application of a gas tungsten arc welding bead... Heat moving source models along with transient heat analysis by finite element method were used to determine weld thermal cycles and isothermal sections obtained from the application of a gas tungsten arc welding beads on Inconel 718 plates. Analytical (Rosenthal’s thick plate model) and finite element results show an acceptable approximation with the experimental weld thermal cycles. The isothermal sections determined by numerical simulation show a better approximation with the experimental welding profile for double-ellipse model heat distribution than Gauss model. To analyze the microstructural transformation produced by different cooling rates in the fusion and heat affected zones, Vickers microhardness measurements (profile and mapping representation) were conducted. A hardness decrement for the heat affected zone (~200 HV0.2) and fusion zone (~240 HV0.2) in comparison with base material (~350 HV0.2) was observed. This behavior has been attributed to the heterogeneous solubilization process of the γ″ phase (nickel matrix), which, according to the continuous-cooling-transformation curve, produced the Laves phase,δ and MC transition phases, generating a loss in hardness close to the fusion zone. 展开更多
关键词 Inconel 718 gas tungsten arc welding (GTAW) weld thermal cycle finite element method heat moving source
下载PDF
Valve Dynamic and Thermal Cycle Model in Stepless Capacity Regulation for Reciprocating Compressor 被引量:9
4
作者 JIN Jiangming HONG Weirong 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2012年第6期1151-1160,共10页
The existing researches of stepless capacity regulation system by depressing the suction valve for reciprocation compressor always adopt hypothesis that the compressor valves are open or close instantaneously, the val... The existing researches of stepless capacity regulation system by depressing the suction valve for reciprocation compressor always adopt hypothesis that the compressor valves are open or close instantaneously, the valve dynamic has not been taken account into thermal cycle computation, the influence of capacity regulation system on suction valves dynamic performance and cylinder thermal cycle operation has not been considered. This paper focuses on theoretical and experimental analysis of the valve dynamic and thermal cycle for reciprocating compressor in the situation of stepless capacity regulation. The valve dynamics equation, gas forces for normal and back flow, and the cylinder pressure varying with suction valve unloader moment during compression thermal cycle are discussed. A new valve dynamic model based on L-K real gas state equation for reciprocating compressor is first deduced to reduce the calculation errors induced by the ideal gas state equation. The variations of valve dynamic and cylinder pressure during part of compression stroke are calculated numerically. The calculation results reveal the non-normal thermal cycle and operation condition of compressor in stepless capacity regulation situation. The numerical simulation results of the valve dynamic and thermal cycle parameters are also verified by the stepless capacity regulation experiments in the type of 3L-10/8 reciprocating compressor. The experimental results agree with the numerical simulation results, which show that the theoretical models proposed are effective and high-precision. The proposed theoretical models build the theoretical foundation to design the real stepless capacity regulation system. 展开更多
关键词 reciprocating compressor valve dynamic thermal cycle model stepless capacity regulation
下载PDF
Thermal cycle and its influence on the microstructure of laser welded butt joint of 8 mm thick Ti-6Al-4V alloy 被引量:8
5
作者 Tian Deyong Yan Tingyan +2 位作者 Gao Qiyu Wang Feiyun Zhan Xiaohong 《China Welding》 EI CAS 2019年第3期61-66,共6页
Ti-6Al-4V alloy is extensively used in the manufacture of components in aviation.In the current study,the laser welding process is adopted to joint the Ti-6Al-4V alloy plate which has the thick of 8 mm.A three-dimensi... Ti-6Al-4V alloy is extensively used in the manufacture of components in aviation.In the current study,the laser welding process is adopted to joint the Ti-6Al-4V alloy plate which has the thick of 8 mm.A three-dimensional finite element model is established to simulate the temperature distribution of laser welding process.The thermal cycle curves are produced on the strength of the simulation results.Meanwhile,the microstructure characteristics of the welded joint are investigated combined with simulation results.The results show that weld zone,heat affected zone and based metal experience similar thermal cycles process and the cooling rate has an important influence on the formation of microstructure.Moreover,the simulation results are well matched with experiment results. 展开更多
关键词 Ti-6Al-4V alloy laser welding temperature distribution thermal cycle MICROSTRUCTURE
下载PDF
Effect of Thermal Cycle on Microstructure and Fracture Morphology in HAZ of HQ130 Steel 被引量:4
6
作者 Li Yajiang Zou Zengda +2 位作者 Cheng Zhunian Wei Xing Jiang Quanchang 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 1996年第2期38-43,共6页
The effect of different peak temperature(Tp) and cooling time (t8/5) on microstructure, hardness, impact toughness and fracture morphology in the heat-affected zone (HAZ) of HQ130 steel was studied by using weld therm... The effect of different peak temperature(Tp) and cooling time (t8/5) on microstructure, hardness, impact toughness and fracture morphology in the heat-affected zone (HAZ) of HQ130 steel was studied by using weld thermo-simulation test. Experimental results indicate that the impact toughness and hardness decrease with the decrease of Tpor increase of t8/5 under the condition of a single thermal cycle. There is a brittle zone in the vicinity of Tp= 800℃, where the impact toughness is considerably low. There is a softened zone in the vicinity of Tp=700℃, where the hardness decreases but the toughness increases. In the practical application of multi-layer and multipass welding, the welding heat input should be strictly limited (t8/5≤20s) so as to reduce the softness and brittleness in the HAZ of-HQ130 steel. 展开更多
关键词 high strength steel welding thermal cycle heat-affected zone MICROSTRUCTURE impact toughness
下载PDF
Effects of Composition and Thermal Cycle on Transformation Behaviors,Thermal Stability and Mechanical Properties of CuAlAg Alloy 被引量:3
7
作者 Yunqing MA, Chengbao JIANG, Lifen DENG and Huibin XUDepartment of Materials Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100083, China 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2003年第5期431-434,共4页
The phase transformation behavior, mechanical properties, and the thermal stability of CuAlAg alloy were studied and minor rare earth (0.1 wt pct La+Ce) was added to improve the mechanical property of the studied allo... The phase transformation behavior, mechanical properties, and the thermal stability of CuAlAg alloy were studied and minor rare earth (0.1 wt pct La+Ce) was added to improve the mechanical property of the studied alloy. It was found that Ag addition in the CuAl binary alloy can improve the stability of martensitic transformation and high Al content leads to the disappearing of martensitic transformation. The tensile strength and strain of the Cu-10.6AI-5.8Ag (wt pct) alloy were measured to be 383.5 MPa and 0.86%, respectively. With rare earth addition, the tensile strain increased from 0.86% to 1.47%. The CuAlAg alloy did not exhibit martensitic transformation on the second heating process. Its poor thermal stability still needs to be improved. 展开更多
关键词 High temperature shape memory alloys CuAlAg Transformation behavior thermal cycle thermal stability Rare earth Mechanical property
下载PDF
The effect of thermal cycle on joint of Ti/stainless steel phase transformation diffusion bonding 被引量:4
8
作者 周荣林 张九海 田锡唐 《China Welding》 EI CAS 2001年第1期14-18,共5页
The effects of thermal cycle parameters on the tensile strength and fracture characteristics of phase transformation diffusion bonding(PTDB) joint of titanium and stainless steel (Ti/SS) were studied in this paper. Wi... The effects of thermal cycle parameters on the tensile strength and fracture characteristics of phase transformation diffusion bonding(PTDB) joint of titanium and stainless steel (Ti/SS) were studied in this paper. With the maximum cyclic temperature of 1 173~1 223 K , the minimum cyclic temperature of 1 073~1 093 K , the heating velocity of 30~50 K/s , the cooling velocity of 15~20 K/s , the cycle numbers of 15~20 and bonding pressure is 13 MPa , the tensile strength of joint is more than 380 MPa , exceeding 80% of that of Ti. 展开更多
关键词 thermal cycle phases transformation diffusion bonding TITANIUM stainless steel
下载PDF
Dimensional instability of LF21 aluminum alloy weldments at room temperature and after thermal cycles 被引量:3
9
作者 刘雪松 田锡唐 徐文立 《China Welding》 EI CAS 2002年第1期89-94,共6页
The unstable dimensional distortion of LF21 aluminum alloy weldments at room temperature and after thermal cycles was studied by use of light interference and CMM. At the same time, distortion mechanism was analyzed f... The unstable dimensional distortion of LF21 aluminum alloy weldments at room temperature and after thermal cycles was studied by use of light interference and CMM. At the same time, distortion mechanism was analyzed from the viewpoint of mechanics and microstructure. Experimental results show that there exists obvious difference of unstable dimensional distortion between LF21 welded specimens under two conditions mentioned above. Under room temperature, dimensional variation of welded specimens will decrease gradually and finally tends to be stable during 130 h after welding. The relative elongation of welded specimen is 4.2×10 -5 . After thermal cycles, distortion of welded specimen is much larger than that at room temperature. After 11 thermal cycles, the dimension will tend to be stable. Dimensional unstable distortion of weldments mainly results from temperature condition, microstructure variation and relaxation of welding residual stress. 展开更多
关键词 LF21 aluminum alloy light interference thermal cycles dimensional instability
下载PDF
Thermal simulation of single thermal cycle for high strength steel pipe 被引量:3
10
作者 Xia Peipei Yang Liuqing +3 位作者 Wu Linen Gu Yunlong Xu Xiaolin You Zongbin 《China Welding》 CAS 2022年第4期59-66,共8页
Single thermal cycle simulation tests were carried out for X80 high strength steel pipes from three steel mills by a Gleeble 3500HS thermal simulation test machine,and coincidence degree of the thermal simulation curv... Single thermal cycle simulation tests were carried out for X80 high strength steel pipes from three steel mills by a Gleeble 3500HS thermal simulation test machine,and coincidence degree of the thermal simulation curve with the set curve under heat inputs of 6–30 kJ/cm was observed;The relationship between different heat inputs and microstructure,impact toughness and hardness of steel pipe CGHAZ(coarse grain heat affected zone)was studied by metallographic examination,impact test and hardness test.The results show that with the increase of heat input,original austenite grain size increases gradually,the lath bainite ratio decreases and the granular bainite ratio increases.The impact toughness of C steel pipe is lower than those of A and B steel pipe,and the impact toughness of CGHAZ from the three steel pipes show different trends:for A steel pipe CGHAZ,impact toughness increases first and then decreases,with the highest value of 270–320 J under 20–25 kJ/cm;for B steel pipe CGHAZ,impact toughness decreases slightly;for C steel pipe CGHAZ,impact toughness increases,with the highest value of 260–300 J under 25 kJ/cm.As the heat input increases,the hardness of three X80 steel pipes CGHAZ shows a decreasing trhighend,and C steel pipe has the largest decreasing range. 展开更多
关键词 X80 pipe single thermal cycle coarse grain heat affected zone heat input
下载PDF
SIMULATION OF WELD THERMAL CYCLE USING THE MODEL OF CARBONITRIDE PARTICLES PRECIPITATION 被引量:2
11
作者 C. B. Cui S. H. Yang Z. Xiong and J. B. Hong (University Navy Engineering, Wuhan, China) 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2000年第1期145-150,共6页
Based on the chasteal nucleation theory, the kinetic precipitation model of carbon - nitride particles in weld HAZ is proposed. Using the model,welding simulation technology and the quantitative metallo- graphic anal... Based on the chasteal nucleation theory, the kinetic precipitation model of carbon - nitride particles in weld HAZ is proposed. Using the model,welding simulation technology and the quantitative metallo- graphic analysis,the precipitation transformation temperatue (PTT) curve is obtained.The data from the simulated welds are in good apreement with the value that the PTT curves predicated. 展开更多
关键词 carbon-nitride simulated weld thermal cycle PTT curve
下载PDF
A study of local brittle zone (LBZ) of 10Ni5CrMoV steel after double thermal cycles 被引量:2
12
作者 张宝伟 魏金山 张田宏 《China Welding》 EI CAS 2005年第2期149-152,共4页
The 10Ni5CrMoV steel examined was a 16 mm thick plate. Specimens measuring 12 mm×12 mm×120 mm were thermally cycled using DM-100A weld simulator with various parameters. The main results are summarized as fo... The 10Ni5CrMoV steel examined was a 16 mm thick plate. Specimens measuring 12 mm×12 mm×120 mm were thermally cycled using DM-100A weld simulator with various parameters. The main results are summarized as follaws. In the coarse-grained austenitized region( Tm = 1 300℃ + 1300℃ ) ,the microstructure is in good toughness. At the condition of Tm = 1 300℃ + 850℃ and t8/5=43 s, the toughness decreases heavily because M-A constituent and twin martensite appear at the prior aastenite grain boundaries. When Tm= 1300℃ + 850℃ or 1300℃ + 730℃ and t8/5 = 85 s, local brittle zone is formed because of relatively coarse granular bainite. 展开更多
关键词 10Ni5SCrMoV steel local brittle zone WELD thermal cycle microstructure inheritance
下载PDF
EFFECTS OF THERMAL CYCLE ON MECHANICAL PROPERTIES AND FRACTOGRAPHY IN HAZ OF HQ130 STEEL 被引量:1
13
作者 B. Liu J.X.Qu W.J.Sun 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2004年第3期274-278,共5页
The effect of different peak temperature T_P) and cooling time (t_(8/5)) on hardness,impact toughness and fracture morphology in the heat--affected zone (HAZ) of HQ130steel was studied by using welding thermo--simulat... The effect of different peak temperature T_P) and cooling time (t_(8/5)) on hardness,impact toughness and fracture morphology in the heat--affected zone (HAZ) of HQ130steel was studied by using welding thermo--simulation test. Experimental results showthat the impact toughness and hardness decrease with the decrease of T_P or increase oft_(8/5) under the condition of a single thermal cycle. There is a brittle zone in the vicinityof T_P=800℃, where the impact toughness is considerebly low. There is softened zonein vicinity of T_P=700℃, Where the harkness decreases but the toughness increases. Inthe practical application of multi--layer and multi--pass welding, the welding heat inputshould be strictly limited (t_(8/5)≤20s) so as to reduce the softness and brittleness in theHAZ of HQ130 steel. 展开更多
关键词 high strength steel welding thermal cycle heat-affected zone impact toughness
下载PDF
Parameter fitting of constitutive model and FEM analysis of solder joint thermal cycle reliability for lead-free solder Sn-3.5Ag 被引量:1
14
作者 周萍 胡炳亭 +1 位作者 周孑民 杨莺 《Journal of Central South University》 SCIE EI CAS 2009年第3期339-343,共5页
The experimental tests of tensile for lead-flee solder Sn-3.5Ag were performed for the general work temperatures range from 11 to 90 ℃ and strain rate range from 5 × 10^-5 to 2 × 10^-2s^-1, and its stress--... The experimental tests of tensile for lead-flee solder Sn-3.5Ag were performed for the general work temperatures range from 11 to 90 ℃ and strain rate range from 5 × 10^-5 to 2 × 10^-2s^-1, and its stress--strain curves were compared to those of solder Sn-37Pb. The parameters in Anand model for solder Sn-3.5Ag were fitted based on experimental data and nonlinear fitting method, and its validity was checked by means of experimental data. Furthermore, the Anand model was used in the FEM analysis to evaluate solder joint thermal cycle reliability. The results show that solder Sn-3.5Ag has a better creep resistance than solder Sn-37Pb. The maximum stress is located at the upper right comer of the outmost solder joint from the symmetric center, and thermal fatigue life is predicted to be 3.796 × 10^4 cycles under the calculated conditions. 展开更多
关键词 lead free solder Sn-3.5Ag alloy Sn-37Pb alloy constitutive model TENSILE FEM analysis thermal cycle reliability
下载PDF
Serrated magnetic properties in metallic glass by thermal cycle 被引量:1
15
作者 李明哲 Sajad Sohrabi +3 位作者 丁大伟 董帮少 周少雄 汪卫华 《Chinese Physics B》 SCIE EI CAS CSCD 2017年第6期271-274,共4页
Fe-based metallic glasses(MGs) with excellent soft magnetic properties are applicable in a wide range of electronic industry. We show that the cryogenic thermal cycle has a sensitive effect on soft magnetic properti... Fe-based metallic glasses(MGs) with excellent soft magnetic properties are applicable in a wide range of electronic industry. We show that the cryogenic thermal cycle has a sensitive effect on soft magnetic properties of Fe78Si9B13 glassy ribbon. The values of magnetic induction(or magnetic flux density) B and Hc coercivity c show fluctuation with increasing number of thermal cycles. This phenomenon is explained as thermal-cycle-induced stochastically structural aging or rejuvenation which randomly fluctuates magnetic anisotropy and, consequently, the magnetic induction and coercivity. Overall,increasing the number of thermal cycles improves the soft magnetic properties of the ribbon. The results could help understand the relationship between relaxation and magnetic property, and the thermal cycle could provide an effective approach to improving performances of metallic glasses in industry. 展开更多
关键词 amorphous soft magnetic materials REJUVENATION AGING cryogenic thermal cycling
下载PDF
EFFECTS OF THERMAL CYCLE ON MECHANICAL PROPERTIES OF SiC PARTICLES REINFORCED MoSi_2 COMPOSITE
16
作者 ZHENG Lingyi JIN Yanping LI Pengxing(The State Key Laboratory of Metal Matrix Composites Materials,Shanghai Jiao Tong University,Shanghai 200030,China) 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 1996年第2期129-134,共6页
MoSi_2 and 30 vol.% SiC_p/MoSi_2 composite have been fabricated by hot pressing (HP).A simulated thermal cycle experiment has been carried out at 1100℃ for 32 h to investigate the stability of the composite system.Co... MoSi_2 and 30 vol.% SiC_p/MoSi_2 composite have been fabricated by hot pressing (HP).A simulated thermal cycle experiment has been carried out at 1100℃ for 32 h to investigate the stability of the composite system.Comparative,mechanical tests,including measurement of flexural strength and fracture toughness at room temperature,have been conducted between materials before and after thermal cycle.It is shown that both the strength and fracture toughness are enhanced by the addition of SiC particles. After thermal cycle,the strength of both materials increases and the toughness decreases by about 20%.The result that the composite system is not corroded intensely by thermal cycle shows that SiC particles are feasible reinforcement for MoSi2. 展开更多
关键词 thermal cycle MoSi_2 SIC mechanical property interface
下载PDF
DIMENSIONAL INSTABILITY OF LD31 Al ALLOY WELDMENTS AT ROOM TEMPERATURE AND AFTER THERMAL CYCLES
17
作者 X.S.Liu H.Y.Fang +2 位作者 W.L.Xu X.T.Tian X.D.Sun 《Acta Metallurgica Sinica(English Letters)》 SCIE EI CAS CSCD 2004年第1期64-70,共7页
The unstable dimensional distortion of LD31 aluminum alloy weldments at room temperature and after thermal cycles was studied by use of light interference and CMM(three-coordinate measuring machines). At the same time... The unstable dimensional distortion of LD31 aluminum alloy weldments at room temperature and after thermal cycles was studied by use of light interference and CMM(three-coordinate measuring machines). At the same time, distortion mechanism was analyzed from the viewpoint of mechanics and micro structure. Experimental results show that there exists obvious difference of unstable dimensional distortion between LD31 welded specimens under two conditions mentioned above. Under room temperature, dimensional variation of welded specimens will decrease gradually and finally tends to be stable during 200h after welding. The relative elongation of welded specimen is 3.0×10-5; After thermal cycles, distortion of welded specimen is much larger than that at room temperature. After 11 thermal cycles, the dimension will tend to be stable. Dimensional unstable distortion of weldments mainly results from temperature condition, microstructure variation and relaxation of welding residual stress. 展开更多
关键词 LD31 aluminum alloy light interference room temperature and thermal cycles dimensional instability
下载PDF
Tailoring microstructure evolution and mechanical properties of a high-performance alloy steel through controlled thermal cycles of a direct laser depositing process
18
作者 Shi-yun Dong Xuan Zhao +5 位作者 Shi-xing Yan Yao-hui Lü Xiao-ting Liu Yu-xin Liu Peng He Bin-shi Xu 《China Foundry》 SCIE CAS 2021年第5期463-473,共11页
Direct laser deposition(DLD),as a popular metal additive manufacturing process,shows advantages of technical flexibility and high efficiency to gain a high-performance alloy steel component.However,during the processi... Direct laser deposition(DLD),as a popular metal additive manufacturing process,shows advantages of technical flexibility and high efficiency to gain a high-performance alloy steel component.However,during the processing of DLD,the deposited steel layer is affected by the subsequent layer depositing.The DLD block shows different microstructure and mechanical properties at the bottom,middle and top of the deposited parts.To date,there are few research works about the effects of inter-layer interval time and laser power on the microstructure evolution and mechanical properties of the deposited layers.In this study,the idle time and laser power layer by layer during DLD of 12CrNi2 steel were controlled to cause the deposited layers to maintain a high cooling rate,while the bottom deposited layer was subjected to a weak tempering effect.Results show that a high proportion of martensite is produced,which improves the strength of the deposited layer.Under the laser scanning strategy of laser power 2,500 W,scanning velocity 5 mm·s^(-1),powder feeding rate 11 g·min^(-1),overlap rate 50%,and a laser power difference of 50 W and a 2 min interval,the tensile strength of the deposited layer of 12CrNi2 steel is in the range of 873-1,022 MPa,and the elongation is in the range of 16.2%-18.9%.This study provides a method to reduce the tempering effect of the subsequent deposition layers on the bottom layers,which can increase the proportion of martensite in the low-alloy high-strength steel,so as to improve the yield strength of the alloy steel. 展开更多
关键词 alloy steel direct laser deposition thermal cycles microstructure evolution mechanical properties
下载PDF
Influence of pipe parameters and heat input on thermal cycle of in-service welding onto active gas pipeline
19
作者 王勇 陈玉华 韩彬 《China Welding》 EI CAS 2007年第4期32-36,共5页
The software of SYSWELD was used to build model and simulate thermal cycle of in-service welding onto active gas pipeline. Influence of pipe diameter, wall thickness and heat input on thermal cycle was studied. The re... The software of SYSWELD was used to build model and simulate thermal cycle of in-service welding onto active gas pipeline. Influence of pipe diameter, wall thickness and heat input on thermal cycle was studied. The results show that t8/5 , t8/3 and peak temperature of inner surface decrease when wall thickness increases from 5 mm to 12 mm. But t8/1 will increases with the increase of wall thickness and will decrease after the wall thickness is larger than 7 mm. Pipe diameter has little influence on thermal cycle and that influence can be ignored when pipe diameter is greater than 273 mm. t8/5 , t8/3 , t8/1 and peak temperature of inner surface will increase with the increase of heat input. 展开更多
关键词 active gas pipeline in-service welding weld thermal cycle numerical simulation
下载PDF
Influence of the secondary welding thermal cycle on the microstructure and property of coarse grain heat-affected zone in an X100 pipeline steel
20
作者 张骁勇 高惠临 +1 位作者 吉玲康 庄传晶 《China Welding》 EI CAS 2010年第3期25-30,共6页
The influence of the secondary thermal cycle on the microstructure of coarse grain heat-affected zone in an XIO0 pipeline steel was investigated by means of a thermal simulation technique and microscopic analysis meth... The influence of the secondary thermal cycle on the microstructure of coarse grain heat-affected zone in an XIO0 pipeline steel was investigated by means of a thermal simulation technique and microscopic analysis method. The property of coarse grain heat-affected zone was characterized by Charpy V-Notch impact properties testing. The results indicated that the experimental steel exhibited local brittleness of intercritically reheated coarse-grained heat-affected zone when the peak tempera- ture of secondary thermal cycle was in the range of two phases region ( ~ and 3/). There were two main reasons for the local brittleness. The first was that the microstructures of intercritically reheated coarse-grained heat-affected zone were not fined although partial grain recrystallization occurred. The second was that M-A islands, which had the higher content, larger size and higher hardness, existed in intercritically reheated coarse-grained heat-affected zone. 展开更多
关键词 X100 pipeline steel secondary thermal cycle MICROSTRUCTURE coarse grain heat-affected zone
下载PDF
上一页 1 2 6 下一页 到第
使用帮助 返回顶部