Method for improving banded structure of 42CrMoA crankshaft
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A banded structure and crankshaft technology, applied in furnaces, heat treatment equipment, manufacturing tools, etc., can solve problems such as unqualified banded structures, and achieve the effect of reducing the level of banded structures and reducing banded structures
Pending Publication Date: 2022-06-24
HENAN ZHONGYUAN SPECIAL STEEL EQUIP MFG CO LTD
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[0004] The object of the present invention is to overcome the deficiencies in the prior art and provide a method for improving the banded structure of 42CrMoA crankshafts by solving the unqualified problem of the banded structure according to the cause of the banded structure. The method combines the forging process and adopts an intermediate The method of billet diffusion and isothermal normalizing after forging finally produces a qualified product with a banded structure that meets the customer's design requirements
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Embodiment 1
[0017] Embodiment 1: A method for improving the belt-like structure of a 42CrMoA crankshaft, the specification of the crankshaft is φ290mm×5025mm, and the chemical composition mass percentages of the steel for the crankshaft are: C: 0.42%, Si: 0.25%, Mn: 0.75%, Ni : 0.33%, Cr: 1.13%, Mo: 0.22%, V: 0.08%, the balance is Fe and other inevitable impurities, and the ingot is cast in a vacuum refining mold.
[0018] The specific steps of this method are as follows:
[0019] Step 1), the hot ingot is opened and forged into an intermediate billet through a hydraulic press, and then the intermediate billet is returned to the furnace to heat 1250±10°C and kept for 15h. Drop to 950±10℃, return to the furnace for 2 hours, leave the furnace and let the material cool to 750-800℃, and send it to the precision forging machine for forging;
[0020] Step 2) After forging, air-cool the forgings to 350-400°C, heat up to 600-650°C with full power, keep for 3 hours, heat up to 860±10°C with full ...
Embodiment 2
[0023] Embodiment 2: A method for improving the banded structure of a 42CrMoA crankshaft, the specification of the crankshaft is φ345mm×5495mm, and the chemical composition mass percentages of the steel for the crankshaft are: C: 0.40%, Si: 0.26%, Mn: 0.71%, Ni : 0.35%, Cr: 1.13%, Mo: 0.22%, V: 0.09%, the balance is Fe and other inevitable impurities, and the ingot is cast in a vacuum refining mold.
[0024] The specific steps of this method are as follows:
[0025] Step 1), the hot ingot is opened and forged into an intermediate billet by a hydraulic press, and then the intermediate billet is returned to the furnace and heated at 1250±10°C for 15 hours. To 950±10℃, return to the furnace for 2 hours, leave the furnace and let the material cool to 750-800℃, and send it to the precision forging machine for forging;
[0026] Step 2) After forging, air-cool the forgings to 350-400°C, heat up to 600-650°C with full power, keep for 3.5h, heat up to 860±10°C with full power, and kee...
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Abstract
The invention relates to a method for improving the banded structure of a 42CrMoA crankshaft, which comprises the following steps of: cogging and forging a hot-fed steel ingot into an intermediate billet through an oil press, returning to a furnace, heating to 1230-1270 DEG C, preserving heat for 10-20 hours, pulling out a trolley, airing the material to 600-650 DEG C, reducing the furnace temperature to 930-970 DEG C, returning to the furnace, preserving heat for 2 hours, discharging, airing the material to 750-800 DEG C, forging and forming by a precision forging machine, quickly cooling the forged piece to 350-400 DEG C after forging, heating to 600-650 DEG C at full power, preserving heat for 1 hour / 100mm, and cooling to the room temperature to obtain the 42CrMoA crankshaft banded structure. The temperature is increased to 840-880 DEG C with full power, heat preservation is conducted for 1-2 h / 100 mm, the temperature is rapidly cooled to 400-450 DEG C after heat preservation is finished, the temperature is increased to 630-670 DEG C with full power, heat preservation is conducted for 4 h / 100 mm, furnace cooling is conducted to the temperature smaller than or equal to 450 DEG C at the speed smaller than or equal to 30 DEG C / h after heat preservation is finished, and the 42CrMoA crankshaft is taken out of a furnace and subjected to air cooling. The problem of the banded structure of a forged 42CrMoA crankshaft is well solved, and the banded structure requirement of the 42CrMoA crankshaft material is met.
Description
technical field [0001] The invention belongs to the technical field of crankshaft manufacturing technology, and in particular relates to a method for improving the belt-like structure of a 42CrMoA crankshaft. Background technique [0002] When the steel ingot is processed by hot pressure, two kinds of structures may appear alternately distributed in layers along the rolling direction. This kind of structure seen under the microscope is called the band structure. After low and medium carbon steels and low alloy structural steels are processed by pressure, a banded structure with alternating layers of ferrite and pearlite often appears; in high carbon alloy steel, a banded structure of carbides appears. The banded structure is the main reason for the anisotropy of the steel, which significantly reduces the transverse plasticity and toughness of the steel. When the banded structure is serious, it will affect the machinability of the steel, the surface finish after processing i...
Claims
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Application Information
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