A kind of low-carbon bainitic weathering steel and its production method
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A low-carbon bainite and production method technology, applied in the field of low-alloy steel production, can solve problems such as accelerated corrosion of pearlite, and achieve the effects of good seawater corrosion resistance, good surface quality, good low-temperature toughness and weldability
Active Publication Date: 2020-06-12
HUNAN VALIN XIANGTAN IRON & STEEL CO LTD
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There are also weathering steels used in the normalized or annealed state, but the microstructure is often composed of ferrite + pearlite, and there is a micro-galvanic interaction between cementite and ferrite in pearlite, along with the anode ferrite The dissolution of cementite in the cathode gradually accumulates on the surface of cementite, which gradually increases the cathode area, resulting in continuous accelerated corrosion of pearlite.
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Embodiment 1
[0033] The weight percentage of chemical composition of steel is C=0.05, Si=0.62, Mn=1.25, P=0.012, S=0.0013, Al=0.033, Ti=0.014, Nb=0.012, Cu=0.66, Ni=0.80, Ca=0.0027 , the balance being Fe and unavoidable impurity elements.
[0034] The production process steps of steel include: use converter, LF furnace and RH furnace to smelt molten steel according to the above composition and continuously cast it into a slab, cool it to room temperature and then grind the surface, then reheat the slab for rolling and finishing, After the surface shot blasting, the heat treatment process of normalizing + accelerated cooling + isothermal aging is carried out, and finally the performance is tested by sampling.
[0035] The production process steps of steel include key process parameters: 250m of Ca wire is fed after the LF furnace, and the soft argon blowing time is 15min; 350m of the Ca wire is fed after the RH furnace, and the soft argon blowing time is 18min; ~14°C, steel flow rate 3.2t / ...
Embodiment 2
[0044] The weight percentage of chemical composition of steel is C=0.04, Si=0.65, Mn=1.23, P=0.013, S=0.0015, Al=0.030, Ti=0.016, Nb=0.015, Cu=0.64, Ni=0.82, Ca=0.0026 , Mo=0.11, Cr=0.17, the balance is Fe and unavoidable impurity elements.
[0045] The production process of steel includes the use of converter, LF furnace and RH furnace to smelt molten steel according to the above composition and continuously cast it into slabs. After the stack is cooled to room temperature, the surface is ground. After the surface shot blasting, the heat treatment process of normalizing + accelerated cooling + isothermal aging is carried out, and finally the performance is tested by sampling.
[0046] The key process parameters in this production method are: 250m of Ca wire is fed after the LF furnace, and the soft argon blowing time is 12min; 350m of the Ca wire is fed after the RH furnace, and the soft argon blowing time is 20min; 15°C, steel flow rate 3.2t / min, crystallizer vibration freq...
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Abstract
The invention discloses low-carbon bainite weathering resistant steel and a production method thereof. The steel is prepared from the following chemical components by weight percent: C equals to 0.03-0.08, Si equals to 0.50-0.80, Mn equals to 1.00-1.80, P is less than or equal to 0.015, S is less than or equal to 0.005, Al equals to 0.02-0.05, Ti equals to 0.008-0.020, Nb is less than or equal to0.020, Cu equals to 0.50-0.80, Ni equals to 0.50-1.00, Ca is less than or equal to 0.006 and Ca / S is greater than or equal to 1.5, the balance of Fe and inevitable impurity elements; and Mo and Cr canbe selectively added, and Mo is less than or equal to 0.30%, and Cr is less than or equal to 0.30%. A microscopic structure of the steel is formed by 95% or above of carbon-free bainite, a little austenite on the crystal boundary and a Cu-Ni ageing precipitated phase, wherein the yield strength thereof is greater than or equal to 485 MPa, the tensile strength is greater than or equal to 585 MPa,the percentage elongation after fracture is greater than or equal to 25%, and the Charpy impact energy in -40 DEG C is greater than or equal to 120 J. The low-carbon bainite weathering resistant steelis clean in steel, uniform in texture, low in internal stress, and good in surface quality, and has the good weather resistance.
Description
technical field [0001] The invention belongs to the technical field of low-alloy steel production, and in particular relates to a low-carbon bainite weathering steel and a production method thereof. Background technique [0002] Weather-resistant steel, also known as atmospheric corrosion-resistant steel, often adds a small amount of alloying elements such as Cu, P, Cr, Ni, and Mo. Compared with ordinary carbon steel, weathering steel has better atmospheric corrosion resistance; and compared with stainless steel, weathering steel not only reduces the cost significantly, but also its mechanical properties and welding performance are easier to meet various engineering needs. Therefore, weathering steel is widely used in bridges, marine engineering, containers, railway carriages and other fields. [0003] The early research on weathering steel mainly focused on the improvement of the ability of the addition of alloying elements to resist atmospheric corrosion. For example, re...
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