Large-thickness rolled steel plate instead of case one for large-sized ball mill and production method thereof

Abstract

The invention discloses a large-thickness rolled steel plate instead of a cast one for a large-sized ball mill and a production method thereof. The steel plate is formed by smelting the following components by weight percent: 0.160-0.190% of C, less than or equal to 0.45% of Si, 1.300-1.500% of Mn, less than or equal to 0.015% of P, less than or equal to 0.005% of S, 0.020-0.050% of Als, 0.015-0.025% of Nb and the balance Fe and inevitable impurities. The method comprises the following steps: smelting molten steel in an electric furnace; refining in an LF refining furnace; performing vacuum treatment in a vacuum degassing furnace; and casting, electroslag remelting, heating, rolling to finished product, cooling, performing hydrogen expanding treatment and normalizing and the like to prepare into the finished product thick steel plate. The invention has the following advantages: 1) the strength and toughness are matched favorably, the yield strength Re is more than or equal to 265 MPa, Rm is 430-600 MPa, the longitudinal impact power is more than or equal to 34J at the temperature of 0 DEG C, and A is more than or equal to 17%; 2) the lamellar tearing resistance is good, and Z is more than or equal to 35%; 3) the steel of the invention is purer, P is less than or equal to 0.015%, and S is less than or equal to 0.005%: 4) the internal quality is more compact, and can satisfy the requirement of the A578C class detection standard; and 5) the maximum thickness of the steel plate can achieve 288mm.

Description

technical field [0001] The invention belongs to the technical field of steel smelting, and in particular relates to a large-thickness rolling replacement cast steel plate for a large ball mill and a production method thereof. Background technique [0002] Large-thickness ball mills use rolling instead of cast steel plates with a thickness of 180~288mm. They are mainly used for the manufacture of fixed guide vanes of hydropower units and disc components under the brackets. The internal quality and thickness are required to be high, and such steel plates are also required to have Better lamellar tear resistance and wear resistance can meet the demand. At present, Q345C / Z35 is commonly used to replace cast steel plates by rolling. This kind of large-thickness steel plates for large ball mills mainly relies on casting production in China. The quality is poor and cannot meet the high-quality needs of large workpieces. Contents of the invention [0003] In view of the above pr...

AI Technical Summary

Problems solved by technology

At present, Q345C / Z35 is commonly used to replace cast steel plates by rolling. This kind of large-thickness steel plates for large-scale ball mills currently mainly relies on casting production in China, and the quality is poor, which cannot meet the high-quality needs of large workpieces.