Chengjiang, China
Chengjiang, China

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Ouyang J.,Shanghai University | Min Y.,Shanghai University | Shao G.,Shanghai University | Xu M.,Shanghai University | And 5 more authors.
Jinshu Rechuli/Heat Treatment of Metals | Year: 2014

Effects of the hot deformation, deformation direction, final deformation temperature, cooling rate after deformation on banded structure of SAE8620H gear steel continuous casting (CC) billet with size of 300 mm×340 mm were comparatively studied. The results show that the sampling position of the CC billet have a great effect on banded structure, the banded structure of the test sample from the billet core displays more serious, at the same time the width of band is more broad. The cooling rate after hot deformation plays a pivotal role on banded structure, proper quick cooling can inhibit the segregation of carbon, as well as banding structure. When increasing the final deformation temperature, the grain size of ferrite-pearlite increases and the banded structure has a increasing tendency. When the deformation is less than 27%, deformation microstructure does not form alternating elements segregation band, also not form banded structure even if slow cooling during full annealing. The formation of banding structure has nothing to do with casting direction of billet, no matter along or vertical the casting direction, banding structure are formed along the deformation direction.

Cheng H.-J.,University of Science and Technology Beijing | Wang F.-M.,University of Science and Technology Beijing | Li C.-R.,University of Science and Technology Beijing | Li G.-Z.,Xingcheng Special Steel Co Ltd
Cailiao Rechuli Xuebao/Transactions of Materials and Heat Treatment | Year: 2010

Phase diagram and sulphide precipitation of a free-cutting microalloyed steel 38MnVS were calculated using Thermo-Calc thermodynamic software, and the effects of lariation of C, Mn, Si, S and V content on precipitation behavior of MnS was studied. The morphology of MnS was observed by using SEM. The simulation of solidification process of steel 38MnVS was done using Scheil-Gulliver model. Based on the observation of the three-dimensional morphology of sulfides in concasting billet of steel 38MnVS, it is indicated that the morphology of sulphide gradually changes from being elongated at the billet edges to laminar in the half from billet edge to centre, and elongated and laminar sulphide is observed in the center of billet. The elongated sulfide and the laminar sulfide formed due to eutectic reaction. Higher alloy elements content in the steel results in the morphology of sulfide changing from the elongated to the laminar.

Ding Q.,Xingcheng Special Steel Co. | Ding Q.,Yanshan University | Li J.,Xingcheng Special Steel Co. | Wang T.,Yanshan University | Wang Q.,Yanshan University
Energy Materials 2014, Conference Proceedings | Year: 2014

The processes of steel-making, rolling and heat treatment have being constantly improving in Xingcheng Special Steel Co., Ltd, and the complete sets of advance production technology and experiences have been formed. A new -50°C high-strength steel plate for large sphere tank has been successfully developed. This steel was micro-alloyed with right amount of Nb, and it has excellent metallurgical quality, lower residual elements and higher performance stability. The relationships between the heat treatment process and the microstructure and mechanical property have been investigated. The results showed that the steel has good strength and toughness, especially, the central portion of the steel has excellent low-temperature toughness, and it can fully meet the technical requirements, namely the yield strength ReL≥500 MPa, the tensile strength 610MPa≤Rm≤730MPa, the elongation A≥17%, the -50°C impact energy KV2≥80J (in the center of plate thickness).

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