Thermal treatment method for reducing hydrogen-induced delayed cracking sensitivity of 1300MPa-level thermoformed steel

Abstract

The invention discloses a thermal treatment method for reducing the hydrogen-induced delayed cracking sensitivity of 1300MPa-level thermoformed steel. The thermal treatment method comprises the following steps of: firstly heating a steel plate inside a heating furnace containing nitrogen protective atmosphere to the temperature of 900-950 DEG C; maintaining the temperature for 180-300 seconds andcarrying out austenization; subsequently quickly putting the steel plate into a mold provided with a temperature control device and carrying out stamping formation; making the quenching and cooling speed be 20-40 DEG C / s; controlling the temperature of the mold to make sure that the quenching temperature of the steel plate is 320-360 DEG C; maintaining the temperature at 320-360 DEG C for 60-600 seconds; afterwards carrying out water quenching until the temperature is equal to room temperature to obtain a lath martensite structure and residual austenite structures; measuring by using an XRD diffraction instrument to obtain that the content of the residual austenite structures is 4% to 6% so as to obtain the thermoformed steel which is resistant to hydrogen-induced delayed cracking. The thermal treatment method disclosed by the invention is suitable for adopting common cold-rolled steel as a raw material, is also suitable for adopting the thermoformed steel produced in a CSP productionline as the raw material, and is better in application prospects and economic benefits in comparison with the method adopting common thermoformed steel.

Description

technical field [0001] The invention relates to the field of high-strength steel production in the metallurgical industry, in particular to a heat treatment method for reducing the hydrogen-induced hysteresis cracking sensitivity of 1300MPa hot-formed steel. Background technique [0002] With the rapid development of the automobile industry, lightweight and safety have become the main direction of the development of the automobile industry. The use of hot-formed steel is currently the most effective measure to improve the safety of automobile crashes, and it is also an important way to reduce weight. At present, low-carbon Mn-B steel plate is the most widely used. After quenching, its structure becomes uniform martensite, and its strength reaches 1300MPa. It is used in A-pillar, B-pillar, front and rear bumpers, hinge reinforcement plates, and door anti-collision beams. , middle channel and other parts. [0003] However, as the strength increases, the problem of delayed cr...

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Problems solved by technology

[0003] However, as the strength increases, the problem of delayed cracking of steel also appears, which has become a major problem restricting the application and development of ultra-high-strength steel.

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