The effect of pre-corrosion on fatigue behavior of high strength steel 38CrMoAl was investigated with a fatigue test method using the accelerated pre-corrosion specimen in the neutral salt spray environment. The metho...The effect of pre-corrosion on fatigue behavior of high strength steel 38CrMoAl was investigated with a fatigue test method using the accelerated pre-corrosion specimen in the neutral salt spray environment. The methods of weight-loss and energy dispersive spectrum （EDS） were adopted. The corrosion weight-loss rate was fitted with the test time using power law, and the relationship between the corrosion weight-loss rate and the time was formulated. Moreover, the fatigue behaviors of the steel for different pre-corrosion time were investigated by the axis-direction tensile fatigue test. The fatigue life distribution characteristics of the pre-corrosion specimens were studied using the statistical probability methods, and the mathematical expectations and the standard tolerances of the material fatigue lives after different pre-corrosion time were obtained. It was found that the crack initiation of the high strength steel was accelerated by the preferential corrosion at the local plastic deform areas. The fatigue life obeys the lognormal distribution perfectly. Furthermore, within the common time range of the engineering, the standard tolerances of the logarithm of the fatigue life were independent of the pre-corrosion time.展开更多
The control of microstructure during hot rolling process of steel is of great importance and will affect the properties of the steel products.According to the production line,a three-dimensional multi-field coupled fi...The control of microstructure during hot rolling process of steel is of great importance and will affect the properties of the steel products.According to the production line,a three-dimensional multi-field coupled finite element model of 24-pass continuous hot rolling process of 38CrMoAl steel rod is established using the finite element software MSC.Marc.Based on the recrystallization kinetics model and the grain growth model,a subroutine written in Fortran is introduced to calculate the recrystallization behavior and microstructure evolution of 38CrMoAl steel during the entire rolling process.The distribution and evolution of variables such as strain,temperature and recrystallization fractions during the rolling process are analyzed.The temperature variations and grain sizes at both the center and surface of the tested steel are compared with the experimental results.And it is found that the simulation results are in good agreement with the experimental ones,confirming the reliability of the established model.展开更多
试验了38CrMoAl钢(%:0.35～0.42C、1.35～1.65Cr、0.15～0.25Mo、0.70～1.10Al)280 Pa 560℃.12 h常规渗氮和170 Pa 560℃3 h快冷至室温循环等离子渗氮对渗氮层组织、硬度、硬度梯度和耐磨性的影响。结果表明,循环等离子体渗氮工艺有利...试验了38CrMoAl钢(%:0.35～0.42C、1.35～1.65Cr、0.15～0.25Mo、0.70～1.10Al)280 Pa 560℃.12 h常规渗氮和170 Pa 560℃3 h快冷至室温循环等离子渗氮对渗氮层组织、硬度、硬度梯度和耐磨性的影响。结果表明,循环等离子体渗氮工艺有利于表层ε相分解,更有利于氮渗入钢中γ′相;在获得相同的渗层表面硬度和硬度梯度下,循环等离子渗氮速度明显高于常规渗氮速度,并改善渗氮后钢的耐磨性。展开更多
经离子渗氮处理的工件具有高的耐磨性和优良的抗疲劳性能,广泛应用于工业生产中。但其渗氮周期长是一大弱点。为了缩短离子渗氮周期,曾采用稀土催渗方法,进行了离子渗氮试验研究,取得了明显效果。本文用 X 射线衍射分析,电镜显微观察等...经离子渗氮处理的工件具有高的耐磨性和优良的抗疲劳性能,广泛应用于工业生产中。但其渗氮周期长是一大弱点。为了缩短离子渗氮周期,曾采用稀土催渗方法,进行了离子渗氮试验研究,取得了明显效果。本文用 X 射线衍射分析,电镜显微观察等方法,进一步研究稀土元素对离子渗氮层组织结构的影响。1 试验方法选用38CrMoAl 钢进行调质处理,得到回火索氏体组织。将其机加工成金相试样。展开更多
基金Funded by the National Natural Science Foundation of China(51001007)
文摘The effect of pre-corrosion on fatigue behavior of high strength steel 38CrMoAl was investigated with a fatigue test method using the accelerated pre-corrosion specimen in the neutral salt spray environment. The methods of weight-loss and energy dispersive spectrum （EDS） were adopted. The corrosion weight-loss rate was fitted with the test time using power law, and the relationship between the corrosion weight-loss rate and the time was formulated. Moreover, the fatigue behaviors of the steel for different pre-corrosion time were investigated by the axis-direction tensile fatigue test. The fatigue life distribution characteristics of the pre-corrosion specimens were studied using the statistical probability methods, and the mathematical expectations and the standard tolerances of the material fatigue lives after different pre-corrosion time were obtained. It was found that the crack initiation of the high strength steel was accelerated by the preferential corrosion at the local plastic deform areas. The fatigue life obeys the lognormal distribution perfectly. Furthermore, within the common time range of the engineering, the standard tolerances of the logarithm of the fatigue life were independent of the pre-corrosion time.
基金This research was funded by the National Key Research and Development Program of China(No.2019YFA0705300)the Joint Research Fund of Natural Science Foundation of Liaoning-the State Key Laboratory of Rolling and Automation,Northeastern University(2019KF0506)the Fundamental Research Funds for the Central Universities of China(DUT19JC26).
文摘The control of microstructure during hot rolling process of steel is of great importance and will affect the properties of the steel products.According to the production line,a three-dimensional multi-field coupled finite element model of 24-pass continuous hot rolling process of 38CrMoAl steel rod is established using the finite element software MSC.Marc.Based on the recrystallization kinetics model and the grain growth model,a subroutine written in Fortran is introduced to calculate the recrystallization behavior and microstructure evolution of 38CrMoAl steel during the entire rolling process.The distribution and evolution of variables such as strain,temperature and recrystallization fractions during the rolling process are analyzed.The temperature variations and grain sizes at both the center and surface of the tested steel are compared with the experimental results.And it is found that the simulation results are in good agreement with the experimental ones,confirming the reliability of the established model.
文摘试验了38CrMoAl钢(%:0.35～0.42C、1.35～1.65Cr、0.15～0.25Mo、0.70～1.10Al)280 Pa 560℃.12 h常规渗氮和170 Pa 560℃3 h快冷至室温循环等离子渗氮对渗氮层组织、硬度、硬度梯度和耐磨性的影响。结果表明,循环等离子体渗氮工艺有利于表层ε相分解,更有利于氮渗入钢中γ′相;在获得相同的渗层表面硬度和硬度梯度下,循环等离子渗氮速度明显高于常规渗氮速度,并改善渗氮后钢的耐磨性。
文摘经离子渗氮处理的工件具有高的耐磨性和优良的抗疲劳性能,广泛应用于工业生产中。但其渗氮周期长是一大弱点。为了缩短离子渗氮周期,曾采用稀土催渗方法,进行了离子渗氮试验研究,取得了明显效果。本文用 X 射线衍射分析,电镜显微观察等方法,进一步研究稀土元素对离子渗氮层组织结构的影响。1 试验方法选用38CrMoAl 钢进行调质处理,得到回火索氏体组织。将其机加工成金相试样。
