Latest ArticlesIn the paper, it is introduced the production process general situation of using 320 mm × 415 mm section to produce 75 kg/m heavy rail in Baotou Steel, and the changes in carbon segregation, grain size and inclusion control of rails produced by 280 mm × 380 mm section are also compared and analyzed.
Heat treatment of U76CrRE rail is simulated by using MMS-200 thermal simulated test machine. The influence of pearlite transformation temperature on its microstructure and hardness is obtained by microstructure observation and hardness testing analysis. And the results show that the lower transformation temperature, the shorter interlamellar spacing in pearlitic microstructure of U76CrRE rail is and the hardness is increasing. At 560 ℃, there is a small amount of martensitic structure in microstructure.
In the paper, it is mainly discussed the low carbon microalloying is used to produce anti-seismic Q235KZ hot rolling H beam, through the reasonable chemical composition design and production process control and other means, the anti-seismic H beam with high strength yield ratio, good toughness and weldability is produced, which changes the comprehensive performance of Q235B hot rolling H beam.
By comparing and analyzing the strength and toughness of X65M product produced through three component system and two hot rolling processes, it is concluded that using low carbon Mn-Nb-Ti component system design to produce hot rolled steel strip with thinner gauge (t≤12.65mm) is more economical and reasonable. At the same time, the TMCP measures combined with large rolling pressure, rapid cooling and low coiling temperature are more beneficial to improve the strength and toughness of material.
In the production of 15Mn seamless steel tube with hot rolling process, the pipe body has obvious banded structure. Through the chemical composition and metallographic examination of pipe body and the analysis of solidification process and rolling process for continuous casting billet, it is concluded that the dendritic segregation in continuous casting billet is the main reason for pipe body to produce banded structure, and the corresponding improvement measures are put forward.
The edge cracks on SPHC coil produced in 2 250mm hot rolling line of Baotou Steel is analyzed. It is concluded that the lower w [Mn]/w [S]of coil can cause micro cracks in the edge and corner of slab, forming defects along with the metal flow to the edge of the strip during rolling process. In practice, when w [Mn]/w [S]≥12, SPHC edge crack can be effectively avoided.
Morphology and composition of red scale defects on hot rolled DP600 surface produced in 2 250 mm hot rolling production line are tested and analyzed. High contents of Si makes it difficult to remove FeO and residual FeO is pressed into matrix, which is the main reason for red scale defects. The industrial test results show that adding phosphorus microelement, reducing heating time of billet and shortly staying at temperature before phosphorus removal machine can significantly reduce red scale and improve surface quality.
The cold drawing of ER70S-6 welding wire steel is from Φ5.5 mm to Φ1.2 mm, and the brittle fracture occurs when drawing to Φ1.3 mm, and all fractures are pencil-tip shaped. Through the test and analysis of metallographic, chemical composition, mechanical properties and scanning electron microscope, the main cause of brittle fracture is the hard massive martensite produced by the composition segregation and the excessive cooling rate during the rolling process. In the process of drawing, hard massive martensitic structure does not change with the deformation of the matrix and produces a large number of cracks around it, and brittle fracture occurs when the deformation is large.
In the paper, it is analyzed the influence of hot rolling mill stiffness on the rolling stability and is introduced the method of evaluating the hot rolling mill stiffness; finally, through the PDA data of CSP mill in Baotou Steel, the mill stiffness analysis is carried out by the data method.
In the paper, the problems occurred in the operation of flying shear control system in 2 250 mm hot rolling production line of Rare Earth Steel Plate Plant are analyzed in detail. Through tracking the actual production situation in the field, various factors that affect the shearing accuracy of flying shear are summarized, and the solution and improvement plan is put forward, so as to improve the hit rate and shearing accuracy of flying shear and optimize the cut loss index.
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