A kind of steel plate for construction machinery with low yield strength ratio q690f and its manufacturing method

Abstract

The invention belongs to the field of structural steel, and discloses a low-yield ratio Q690F steel plate for engineering machinery and a manufacturing method thereof. The manufacturing method has the following steps: Step 1: Smelt molten steel according to the set composition and cast it into a slab, the composition of which is C 0.05-0.07%, Si 0.10-0.15%, Mn 1.7-1.8%, P≤ 0.012%, S≤0.005%, Cr 0.6~0.8%, B 0.005~0.009%, Ti 0.01~0.03%, Zr 0.01~0.03%, the balance is Fe; Step 2: Heating the slab to 1220~1250℃, Carry out hot rolling, the starting temperature of hot rolling is 1100-1150°C, and the final rolling temperature is 900°C-950°C; step 3: the steel plate is air-cooled after exiting the water. Since the hot-rolled steel plate of the present invention cancels the quenching and tempering heat treatment process and the offline tempering process after the TMCP process, the reduction of the process is realized and the production cost is reduced. At the same time, the hot-rolled steel plate of the present invention adopts high temperature The process route of final rolling + continuous cooling is simple and controllable, and can be implemented smoothly on site, which is conducive to the popularization and application of this process technology.

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 been used for large-scale operations in deep sea and polar regions, and the performance requirements for construction machinery steel are getting higher and higher, high strength, high toughness and low yield ratio has become the future direction of development. 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, can effectively reduce the brittle fracture of machinery and equipment under different service conditions. For reducing the yield ratio, it can maximize the design safety factor of the equipment, increase ...

AI Technical Summary

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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