This work consists of evaluating the quality of the mechanical parameters of large-diameter steels, i.e. 20, 25, 28 and 32, through a process of recycling scrap metal that fills garages, rubbish dumps, gutters and oth...This work consists of evaluating the quality of the mechanical parameters of large-diameter steels, i.e. 20, 25, 28 and 32, through a process of recycling scrap metal that fills garages, rubbish dumps, gutters and other abandoned sites, as well as imported concrete reinforcing steel sold in the Republic of Guinea. To carry out this important work, a number of mechanical tensile and bending tests and a microscopic analysis combining two devices, an electron microscope and a photographic camera, were carried out. The samples were taken from sampling areas in the major communes of Conakry, namely: Casse Sonfonia, Matoto and Kagbélen. The tensile strength values of the large dimensions 20, 25, 28 and 32 are given in the tables.展开更多
In order to reveal the mechanism and condition of void closure in large diameter steel rod during horizontal- vertical （H-V） groove rolling process, a three-dimensional thermomechanicaily coupled finite element mode...In order to reveal the mechanism and condition of void closure in large diameter steel rod during horizontal- vertical （H-V） groove rolling process, a three-dimensional thermomechanicaily coupled finite element model was es- tablished for 9-stand H-V groove rolling process aiming at a 4150 mm steel rod production line. A spherical hole with diameter from 2 to 10 mm was preset into the center of continuous casting billet with a rectangle cross section of 300 mmX 360 mm in this model to simulate the void defect, and then finite element analyses were carried out to observe and quantify the void shape evolution in each pass on the three orthogonal coordinate plane sections. The re- suits showed that the void was formed roughly in the reduction and extension directions, and crushed gradually from spherical shape to an approximate ellipsoid, micro-crack and finally to be closed. A quantitative analysis was carried out by using elliptic radii and closure ratio to describe this evolution process; it indicated that the longest axis of the ellipsoid coincided with the rolling line, and the second and third axes were alternatively ihorizontal and vertical on the exit cross section according to change of the reduction direction in H-V groove. The void closure behavior during H- V rolling was more complicated than that of common horizontal rolling, and the influence of groove type and the ex- tension coefficient on the void closure ratio was presented. Finally, a pilot rolling experiment was performed on a 5- stand H-V experimental mill to verify the numerical simulation results, and the experimental results are in good agree- ment with the numerical simulation results.展开更多
采用热穿轧工艺试制大口径TC4钛合金无缝管,测试分析了试制的160 mm×8 mm TC4钛合金无缝管的加工精度、表面质量、显微组织与力学性能。结果表明:热穿轧TC4钛合金无缝管的表面质量、尺寸精度和力学性能均合格;管材的加工态组织...采用热穿轧工艺试制大口径TC4钛合金无缝管,测试分析了试制的160 mm×8 mm TC4钛合金无缝管的加工精度、表面质量、显微组织与力学性能。结果表明:热穿轧TC4钛合金无缝管的表面质量、尺寸精度和力学性能均合格;管材的加工态组织主要由变形魏氏组织和少量网篮状组织构成,其冲击韧性好,延伸率达到16%以上,无需热处理就可进行冷轧加工,以获得更高精度和表面质量的钛合金无缝管;热穿轧工艺可用来制备大口径TC4钛合金无缝管,具有金属利用率高、流程短、能耗低等优点,能够满足工业生产要求。展开更多
文摘This work consists of evaluating the quality of the mechanical parameters of large-diameter steels, i.e. 20, 25, 28 and 32, through a process of recycling scrap metal that fills garages, rubbish dumps, gutters and other abandoned sites, as well as imported concrete reinforcing steel sold in the Republic of Guinea. To carry out this important work, a number of mechanical tensile and bending tests and a microscopic analysis combining two devices, an electron microscope and a photographic camera, were carried out. The samples were taken from sampling areas in the major communes of Conakry, namely: Casse Sonfonia, Matoto and Kagbélen. The tensile strength values of the large dimensions 20, 25, 28 and 32 are given in the tables.
基金Sponsored by National Natural Science Foundation of China(51005197,51101136)
文摘In order to reveal the mechanism and condition of void closure in large diameter steel rod during horizontal- vertical （H-V） groove rolling process, a three-dimensional thermomechanicaily coupled finite element model was es- tablished for 9-stand H-V groove rolling process aiming at a 4150 mm steel rod production line. A spherical hole with diameter from 2 to 10 mm was preset into the center of continuous casting billet with a rectangle cross section of 300 mmX 360 mm in this model to simulate the void defect, and then finite element analyses were carried out to observe and quantify the void shape evolution in each pass on the three orthogonal coordinate plane sections. The re- suits showed that the void was formed roughly in the reduction and extension directions, and crushed gradually from spherical shape to an approximate ellipsoid, micro-crack and finally to be closed. A quantitative analysis was carried out by using elliptic radii and closure ratio to describe this evolution process; it indicated that the longest axis of the ellipsoid coincided with the rolling line, and the second and third axes were alternatively ihorizontal and vertical on the exit cross section according to change of the reduction direction in H-V groove. The void closure behavior during H- V rolling was more complicated than that of common horizontal rolling, and the influence of groove type and the ex- tension coefficient on the void closure ratio was presented. Finally, a pilot rolling experiment was performed on a 5- stand H-V experimental mill to verify the numerical simulation results, and the experimental results are in good agree- ment with the numerical simulation results.
文摘采用热穿轧工艺试制大口径TC4钛合金无缝管,测试分析了试制的160 mm×8 mm TC4钛合金无缝管的加工精度、表面质量、显微组织与力学性能。结果表明:热穿轧TC4钛合金无缝管的表面质量、尺寸精度和力学性能均合格;管材的加工态组织主要由变形魏氏组织和少量网篮状组织构成,其冲击韧性好,延伸率达到16%以上,无需热处理就可进行冷轧加工,以获得更高精度和表面质量的钛合金无缝管;热穿轧工艺可用来制备大口径TC4钛合金无缝管,具有金属利用率高、流程短、能耗低等优点,能够满足工业生产要求。
