A kind of high-strength quality steel plate q550ez35 with a thickness of 300mm and its production method

Abstract

The invention particularly relates to extra-thick high-strength quenched and tempered steel Q550EZ35 with thickness being 300 mm for a hydropower station, and a production method of the extra-thick high-strength quenched and tempered steel Q550EZ35. Basic elements such as C, Mn, Si, P, S and AlS and alloying elements such as Cr, Mo, V, Ni, Nb, Ti, B and Cu are combined and matched, and under the premise of ensuring the steel plate strength, the low-temperature impact toughness and welding performance of a steel plate are improved. By adopting water-cooled ingot casting, the solidification speed of molten steel is increased, the defects of loosening, segregation and the like are overcome advantageously, and meanwhile, the deviation of compositions at the head and the tail of the steel plateis reduced. Through rolling at the low speed and large pressure and high-temperature tempering after rolling, internal stress release of the steel plate is facilitated, meanwhile, the hydrogen content is decreased, the flaw detection quality of the steel plate is improved, and NB / T 47013.3-2015 I-level requirements are met. The structure is homogenized through pre-normalizing, then quenching andtempering are conducted, thus the uniformity of the whole steel plate performance is improved advantageously, through cooling speed controlling and low-temperature long-term tempering after quenchingand tempering, the low-temperature impact toughness and strength matching of the steel plate are ensured advantageously, the performance is stable, and mass production is easy to realize.

Description

technical field [0001] The invention belongs to the technical field of production of extra-thick quenched and tempered steel plates, and in particular relates to a 300mm thick extra-thick high-strength and tempered steel Q550EZ35 and a production method thereof. Background technique [0002] The fixed guide vane is one of the most important castings and forgings in the water guide mechanism of the hydro-generator set, and its manufacture has always been a major problem in the manufacture of large-scale hydro-turbine sets. It is generally processed and manufactured by sand casting, electroslag casting and forging. Sand casting is used for production, and the internal quality of castings is unstable, and common casting defects such as shrinkage porosity, shrinkage cavities, pores, inclusions, and cracks are prone to occur. Compared with conventional sand casting and forging guide vanes, the comprehensive quality of electroslag casting guide vanes has been greatly improved, bu...

AI Technical Summary

Problems solved by technology

Compared with conventional sand casting and forging guide vanes, the comprehensive quality of electroslag casting guide vanes has been greatly improved, but the production cost is high

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