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Surface-controllable composite strengthening method for forged steel crankshaft material

A technology for crankshafts and forging steels is applied in the field of surface controllable composite strengthening of forged steel crankshaft materials, which can solve the problems of limited improvement in surface hardness and fatigue performance, and achieve the effects of low cost, production cost saving, and hardness reduction requirements.

Active Publication Date: 2016-03-09
INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the strengthening effect of the fillet rolling technology on the crankshaft made of alloy steel is far lower than that of the crankshaft made of cast iron, and the improvement of surface hardness and fatigue performance is limited.

Method used

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  • Surface-controllable composite strengthening method for forged steel crankshaft material
  • Surface-controllable composite strengthening method for forged steel crankshaft material
  • Surface-controllable composite strengthening method for forged steel crankshaft material

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0044] The chemical composition of 42CrMoA alloy steel for forged steel crankshaft is (wt.%): C0.41%, Si0.23%, Mn0.75%, S0.024%, P0.015%, Cr1.12%, Mo0.22 %, Cu0.02%, the balance of Fe. The supply state of 42CrMoA alloy steel is forged, and the diameter of the test rod is 20mm (the size used for surface mechanical rolling and nano-processing).

[0045] Using the surface controllable composite strengthening method of the present invention to treat the forged steel crankshaft with 42CrMoA alloy steel, the specific process is as follows: (1) heat treat the 42CrMoA alloy steel by adopting a heat treatment process (quenching and tempering treatment). Firstly, the 42CrMoA alloy steel is subjected to normalizing pretreatment, the normalizing temperature is 900°C, the holding time is 300min, and the cooling method is air cooling. Then the 42CrMoA alloy steel is quenched and quenched by a resistance heating furnace. The quenching temperature of the resistance heating furnace is 850°C,...

Embodiment 2

[0048] The chemical composition, supply state and size of the test rod of the 42CrMoA alloy steel for the forged steel crankshaft selected in this embodiment are all the same as those in Embodiment 1.

[0049] The forged steel crankshaft is treated with 42CrMoA by using the surface controllable composite strengthening method of the present invention, and the specific process is as follows: (1) The 42CrMoA alloy steel is heat treated by a heat treatment process (intermediate frequency quenching + low temperature tempering process). The intermediate frequency induction hardening is carried out in the intermediate frequency induction hardening furnace, the quenching temperature is 860°C; the low temperature tempering is carried out in the resistance heating furnace, the tempering temperature is 240°C, the holding time is 120min, and air cooling after heat preservation, the finally obtained 42CrMoA alloy steel surface layer In the larger depth range (≥3mm), there is acicular marten...

Embodiment 3

[0052] The chemical composition, supply state and size of the test rod of the 42CrMoA alloy steel for the forged steel crankshaft selected in this embodiment are all the same as those in Embodiment 1.

[0053] The forged steel crankshaft is treated with 42CrMoA by using the surface controllable composite strengthening method of the present invention, and the specific process is as follows: (1) The 42CrMoA alloy steel is heat treated by a heat treatment process (intermediate frequency quenching + low temperature tempering process). The medium frequency induction hardening is carried out in the medium frequency induction hardening furnace, the quenching temperature is 860°C; the low temperature tempering is carried out in the resistance heating furnace, the tempering temperature is 210°C, the holding time is 120min, and air cooling after heat preservation, the final 42CrMoA alloy steel surface layer is obtained In the larger depth range (≥3mm), there is acicular martensitic struc...

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Abstract

The invention discloses a surface-controllable composite strengthening method for a forged steel crankshaft material, and belongs to the technical field of metal material surface strengthening. According to the method, heat treatment and surface mechanical rolling nanocrystallization treatment are combined, and surface-controllable composite strengthening treatment is carried out on a rotary piece of the forged steel crankshaft material. By means of the adjustment on a heat treatment technology (quenching and tempering treatment or medium-frequency quenching and low-temperature tempering treatment), the rotary piece can obtain organization structures different in hardness and high in plasticity; and then surface mechanical rolling nanocrystallization treatment is carried out on the rotary piece subjected to heat treatment, so that the surface grain size of the material is lowered, the surface hardness of the material is improved, the hardness distribution state of the material on the surface layer in the depth direction is adjusted, and meanwhile the surface smoothness of the material is improved. After surface-controllable composite strengthening treatment, controllable preparing of the structures, the grain size, surface smoothness and hardness distribution of the rotary piece of the forged steel crankshaft material is achieved, and a crankshaft can meet different use requirements.

Description

technical field [0001] The invention relates to the technical field of metal material surface strengthening, in particular to a controllable composite strengthening method for the surface of a forged steel crankshaft material. Background technique [0002] As one of the core moving parts in the engine, the quality, performance and reliability of the crankshaft are directly related to the service performance, safety performance and service life of the engine and even the vehicle or ship. When the engine is working, the crank bearing is subject to large alternating bending stress and torsional stress, and the stress distribution is extremely uneven. Under the combined action of complex stress, fatigue cracks are prone to occur at the stress concentration part, resulting in fatigue fracture of the crankshaft, which seriously affects the safety of the engine. performance. Among them, the transition fillet between the main journal of the crankshaft and the crank and the transiti...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D9/30C21D6/00C21D7/04
CPCC21D6/002C21D7/04C21D9/30
Inventor 张伟华王镇波卢柯张凯
Owner INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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