XUAN Fu-zhen, TU Shan-dong, WANG Zheng-dong, GONG Jian-ming. Estimation of High-temperature Fracture Mechanics Parameter for Cracks in Mismatched Weldment[J]. Journal of Materials Engineering, 2003, 0(10): 3-6.
Creep crack growth (CCG) analysis and residual life prediction of the mismatched weldment is a high degree mechanical problem since it is affected by many factors such as material non-homogeneity of weld, base and heat affected zone and geometry of the weldment and its constituents and the location of pre-existing cracks. A concept of equivalent creep strain rate (ECSR) and the corresponding calculation approach, which could reflect the influence of all factors, were presented in this work. On the basis of the proposed ECSR and reference stress, an estimation approach for high temperature fracture mechanics parameter C* was then derived. Nonlinear finite element analysis of 48 compact tension specimens with low-mismatch and over-mismatch in creep behaviour has been performed. Overall good agreement between the proposed method and the FE results provide confidence in the use of the proposed method in practice.
GUO Ran, SHI Hui-ji, YAO Zhen-han. Simulation of the Thermal-mechenical Fatigue Behavior for Particle Reinforced Composites[J]. Journal of Materials Engineering, 2003, 0(10): 7-8,41.
A new thermal-creep-plastic element is introduced based on Voronoi Cell finite element model.With the element, the influence of the relative phases of mechanical fatigue and thermal fatigue loading on the thermo-mechanical fatigue hysteresis loop, and the influence of the topological micro-structure of inclusions on the thermo-mechanical fatigue behavior have been analyzed.
LUO Guo-qing, QIAO Sheng-ru. Influence of Loading Rates on 3D-C/SiC Tensile Properties at Different Temperature[J]. Journal of Materials Engineering, 2003, 0(10): 9-10,39.
The tensile performance of 3D-C/SiC preformed by CVI method was investigated in different temperatures and tensile crosshead displacement rates. The tensile experiment was carried out in vacuum condition. Testing temperature were room temperature, 1100℃,1500℃ and displacement rates are 0.008,0.06,5.82 mm/min respectively. Experimental results show that fracture stress increases as the crosshead displacement rate increased at room temperature, but it is in reverse at 1500℃. The fracture stress does not chang as the crosshead displacement rate varied at 1100℃. The fracture strain decreases and the initial modulus increases as the crosshead displacement rate increased.
XU Fu-min, ZHU Shi-jie, ZHAO Jie, WANG Fu-gang. Fatigue Crack Growth and Subcritical Propagation Behavior in a SiCp/Al Matrix Functionally Graded-composite[J]. Journal of Materials Engineering, 2003, 0(10): 11-13.
The SiCp/Al graded composite was fabricated by powder metallurgy processing and its fatigue crack growth behavior and subcritical crack propagation behavior were investigated. Fatigue crack growth was in direction of from 30% to 5%SiC layer under sinusoidal wave-form. The retardation of fatigue crack growth was found. Under monotonic loading, it was found that crack resistance increases with crack extension when crack growth was in direction of from 30% to 5%SiC layers.
LIU Shao-lun, HE Yu-huai, WUN Jing-long. Thermal-mechanical Fatigue Behavior of an Unidirectional Fiber-reinforced Metal-matrix Composite Laminates[J]. Journal of Materials Engineering, 2003, 0(10): 14-15,22.
In this paper, the experimental study and macro-micro analysis about the behavior of thermal-mechanical fatigue (TMF) were conducted in B/Al metal-matrix composite with thermal cycle of 250℃ to 350℃. The results showed that S-N curves of in-phase and out-phase intersect at the point of FPF, above which the life of in-phase TMF is less than that of out-of-phase TMF but the case is opposite below the point. Otherwise the life of TMF is always less than that of 250℃ isothermal and 350℃ isothermal. Furthermore,the fatigue crack come of the interface between fiber and matrix material because the interface reaction acts as the primary part of damage on TMF.
DING Hui, ZHANG Guo-qing. Simulation of the Influence of the Coating Process on the Brittleness of Ti-4Al-22V Alloy[J]. Journal of Materials Engineering, 2003, 0(10): 16-18.
Simulation of heat-treatment for coating process of Ti-4Al-22V alloy was performed using the vacuum coater and the heat-treating. The hardness was measured by using the vickers and the microstructure was observed with the electron microscope, the analysis of electron-scanning and the element energy spectrum were preformed by using the JXA-8800R electron probe microanalyser. The results showed that the elevated temperatures caused the brittleness of Ti-4Al-22V alloy and there exists a ductile-brittle transformation temperature about 300℃, the elimination of the brittleness of Ti-4Al-22V alloy can be reached by performing the annealing treatment on the range of 450～550℃ and it can result in the recrystallization and the improvement of ductility. The annealing treatment can be performed before or after the coating process.
GONG Jian-ming, JIANG Yong, TU Shan-dong. Effect of Carbon Migration on Creep Rupture Time of Cr5Mo Dissimilar Welded Joints using Ni-based and Austenitic Weld Metal[J]. Journal of Materials Engineering, 2003, 0(10): 19-22.
Based on the consideration of economy and being easy to construct on site, dissimilar welded joints are usually used in engineering application. Cr5Mo dissimilar welded joints are widely used at elevated temperature in the oil refining and petrochemical installation. In this paper,the effect of carbon migration on creep rupture strength and time of Cr5Mo dissimilar welded joints with Ni-based and austenitic weld metal is studied by thermal aging treatment and long term creep testing. The results show that creep rupture time of Cr5Mo dissimilar welded joints with austenitic weld metal decrease due to carbon migration and is about 50% of that with Ni-based weld metal.
JIANG Yun-peng, YUE Zhu-feng. FEM Analysis of Stress and Strain on Double Shear Specimens of Metal Matrix Composites at High Temperature[J]. Journal of Materials Engineering, 2003, 0(10): 23-25.
The stress and strain distributions of double shear creep specimens were analyzed by the method of FEM. The results show that this kind of specimens can provide of metal matrix composite a relative uniform shear stress in the shear zone center. The stress and strain distribution characteristics are dependent on the angle θ between the fiber-plane and loading direction. With the decreasing of θ, the homogeneous degree of stress distribution is improving. At θ=45°, the creep strain rate of double shear creep specimens is maximum. Double shear creep specimens can provide a uniform shear stress distribution and can be used to study the creep behavior of metal matrix composites.
DONG Jian-xin, ZHANG Mai-cang, ZENG Yan-ping, XIE Xi-shan. Simulation of Stress Distribution and Precipitate Influence at the Crack Tip of CT Sample in Superalloy[J]. Journal of Materials Engineering, 2003, 0(10): 26-28.
The stress distribution and precipitation phase around creep crack during the initial stage of creep crack propagation of IN718 alloy were investigated, and the stress intensity factor was calculated at different stress levels by using FEM calculation method. The agreement of the calculated data with the tested data shows that the FEM model and the calculation method are suitable for studying the effect of creep crack propagation in superalloys. Furthermore, the influence of precipitation phase and the plastic zone around the precipitation phase on stress distribution was studied.Calculation results show that the precipitation of α-Cr phase within plastic zone does not promote the creep crack propagation.
CHENG SHI-chang, LIN ZHAO-jie, LIU Zheng-dong, YANG Gang. The Effect of Carbon and Nitrogen Contents on the Strength of 2Cr21Ni12N Valve Steel[J]. Journal of Materials Engineering, 2003, 0(10): 29-31.
The effect of (C+N) content on the strength of 2Cr21Ni12N valve steel was experimentally investigated, including hardness test and tensile test at room temperature and high temperature after solid solution treatment and ageing treatment respectively. The creep rupture strength and bending fatigue test at high temperature were also conducted. It has showed that the hardness and strength of the steel increase with the increase of (C+N) content.
ZHOU Bin-sheng, TANG Xiao-ying, WANG Zheng-dong, WU Dong-di. Application of Parameter Q*(t) for Correlation of Creep Crack Growth Rate[J]. Journal of Materials Engineering, 2003, 0(10): 32-33,45.
A new parameter, Q*(t) is modified from Q* in this paper for correlation with creep crack growth rate (CCGR) instead of C* integral. Taking into account of effective factors, including temperature, stress field and activation energy, the new parameter Q*(t) shows a good correlation of creep crack growth rate under various stress levels and temperatures. Q*(t) not only reveals the physical mechanism of creep fracture and creep crack growth, but also correlates with the whole stages of creep crack growth.
KANG Guo-zheng, GAO Qing, CAI Li-xun, YANG Xian-jie. Experimental Study on the Temperature-dependent Cyclic Deformation of SS304 Stainless Steel[J]. Journal of Materials Engineering, 2003, 0(10): 34-36.
The uniaxial/multiaxial strain cyclic deformation and ratcheting of SS304 stainless steel at ambient and elevated temperatures were studied through systematical experiments.The temperature-dependence of strain cyclic deformation and ratcheting was discussed in detail. Simultaneously, the effects of different loading conditions at certain temperature on the strain cyclic deformation and ratcheting were analyzed. It is shown by experiments that the cyclic deformation behaviors of the material have a great dependence on the ambient temperatures,and different features resulted from different temperatures, especially to a specific temperature range of 400~600℃, i.e.,the material presents a markedly dynamic stain aging.
XIE Guo-sheng, YIN Zhi-min, DING Hui, YANG Bing. Design and Deposition of Erosion Resistance Nanosuperlattice Coatings Used in Last Blades of Steam Turbine[J]. Journal of Materials Engineering, 2003, 0(10): 37-39.
This investigation aimed at the failure mechanism of liquid impact erosion occured on the last blades of steam turbine and the complicated operation status in the last blades of steam turbine, the multi-layer nanosuperlattice composite coatings with high hardness, fine tenacity and favorable strength combined with substratum had been designed. Finally, the CNx/TiN multi-layer composite coatings were deposited onto 2Cr13 stainless steel substratum usually used the last blades of steam turbine by combination of DC reaction magnetron sputtering deposition with multi-arc plating.
ZHU Yue-mei, TAO Zhi-gao. Technical Innovation of Material High Temperature Testing[J]. Journal of Materials Engineering, 2003, 0(10): 40-41.
Test quality, automation and data reliability are main factors of creep test. Technical innovation of temperature control, automatic level adjusting and data processing system was realized. The technique provides basis of remote control for creep test.
ZHOU Can-dong, FAN Jun-fei, LIN Yi-jian, SUN De-sheng, LE Hai-rong, ZHANG Jing-guo. Mechanical Properties and Microstructure of Spray Formed Roll Material[J]. Journal of Materials Engineering, 2003, 0(10): 42-45.
The mechanical properties and microstructure of a high speed steel (HSS) for roll have been studied.In Comparison with the as-cast HSS, the as-sprayed HSS had fine grain and segregation-free microstructures and its carbides distributed uniformly. The morphology and types of the carbides in as-sprayed HSS were different from those in as-cast HSS. Because there was more retained austenite in as-sprayed specimen than that in as-cast specimen, the as-sprayed HSS had lower Vickers hardness. The results of the high temperature tensile experiment show that the elongation of the as-sprayed HSS specimens is very large when deformation in the temperature range of 780~810℃. So the as-sprayed HSS can be strongly deformed in this temperature range.
SHEN Fu-zhong, DING Yi, DONG Tai-bin, A Bu-du. Two Mechanisms for Fracture of Furnace Tube at Elevated Temperature[J]. Journal of Materials Engineering, 2003, 0(10): 46-48.
It is showed that two mechanisms existed in fracture of furnace tubes operated at high temperature by investigation in an event of the thermal shock. Overheat induced early creep rupture with the obvious deformation in general and the thermal shock led rapidly to brittle fracture. In analysis of causes of failure, Manson-Haferd Parameter extrapolation was discussed. It is discussed for distribution of the thermal stress along the tube thickness and its peak. A safe curve for the thermal shock was showed.
