Low-yield-ratio Q690F steel plate for engineering machinery and manufacturing method thereof

Abstract

The invention belongs to the field of constructional steel and discloses a low-yield-ratio Q690F steel plate for engineering machinery and a manufacturing method thereof. The manufacturing method of the low-yield-ratio Q690F steel plate for engineering machinery comprises the following steps of, firstly, casting molten steel of set components into casting blanks, wherein the set components are composed of, by weight percentage, 0.05-0.07% of C, 0.10-0.15% of Si, 1.7-1.8% of Mn, less than or equal to 0.012% of P, less than or equal to 0.005% of S, 0.6-0.8% of Cr, 0.005-0.009% of B, 0.01-0.03% of Ti, 0.01-0.03% of Zr and Fe as balance; secondly, heating the casting blanks to 1220-1250 DEG C to perform hot rolling at a starting temperature of 1100-1150 DEG C and a finishing temperature of 900-950 DEG C; thirdly, air-cooling discharged steel plates. By cancelling quenched-tempered heat treatment and saving post-TMCP (thermal mechanical control processing) off-line quenching processes, themanufacturing method of the low-yield-ratio Q690F steel plate for engineering machinery can achieve technical reduction and reduce production costs; meanwhile, hot-rolling the steel plates is performed through technical processes of high-temperature finishing rolling and continuous cooling, which are simple and controllable and can be smoothly implemented on site, thereby facilitating popularization and application of the manufacturing method of the low-yield-ratio Q690F steel plate for engineering machinery.

Description

Technical field [0001] The invention belongs to the field of structural steel, and in particular relates to a low yield ratio Q690F steel plate for engineering machinery and a manufacturing method thereof. Background technique [0002] At present, with the in-depth development and utilization of energy, large-scale machinery industry equipment has carried out large-scale operations in areas such as deep sea and polar regions. The performance requirements of steel for construction machinery are getting higher and higher, with high strength, high toughness and low yield ratio. Has become the future development direction. In terms of strength and toughness, it can effectively reduce the structural weight and manufacturing cost of construction machinery and equipment, and at the same time, it can effectively reduce the brittle fracture of machinery and equipment under different service conditions. For reducing the yield ratio, the design safety factor of the equipment can be maximiz...

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Problems solved by technology

[0004] Chinese patent documents CN106636889A and CN103556076A all adopt off-line quenching and tempering process (quenching + tempering) after rolling to prepare Q690F high-strength and high-toughness steel plate, the production process is complicated, and the production efficiency is low

However, through the above-mentioned composition and process, the yield ratio of the steel plate is relatively high, which cannot comprehensively satisfy the relationship between strength and toughness and low yield ratio.

[0005] To sum up, the existing Q690MPa high-strength construction machinery steel has problems such as high yield ratio, large amount of alloy addition and complicated process.

In order to reduce the yield ratio, the method of adding a large amount of alloying elements cannot coordinate the cost and process well

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