Steel for in-situ nano reinforced and toughened crankshaft

Abstract

The invention relates to steel for an in-situ nano reinforced and toughened crankshaft. The steel is characterized by comprising the following components in percentage by weight: 0.40 to 0.42 percent of carbon, 0.23 to 0.27 percent of silicon, 0.70 to 0.74 percent of manganese, 1.08 to 1.18 percent of chromium, 0.21 to 0.23 percent of molybdenum, 0.005 to 0.015 percent of titanium, 0.02 to 0.04 percent of vanadium, 0.010 to 0.040 percent of aluminum, 0.014 to 0.025 percent of sulfur and less than or equal to 0.015 percent of phosphorus. According to the steel, trace alloy elements vanadium and rare earth nanowires are added in the refining process, and a series of operations of refining steps are improved, so that a large number of in-situ nano-particles which are dispersively distributed are formed in the processes of steel melt, solidification and the like, the particle size is 2-30 nanometers, the distance between the nano-particles is 20-100 nanometers, 109-1012 nano-particles are contained in each crystal grain, a large number of in-situ nano-particles are dispersed and distributed, so that the generation of columnar crystals is inhibited, fine isometric crystals are formed, macrosegregation is improved, the formation and size of brittle phases are reduced, and the strength and plasticity of the crankshaft steel are improved; the in-situ nanoparticles and the matrix are in a coherent or semi-coherent relationship, dislocation is not easy to accumulate, stress concentration is reduced, so that the toughness is not reduced, and the contradictory problem of strengthening and toughening is solved.

Description

technical field

[0001] The invention belongs to the field of steel preparation for crankshafts, in particular to an in-situ nano-reinforced and toughened steel for crankshafts. Background technique

[0002] The crankshaft is the most important part of the engine, with complex geometry and very harsh working conditions. When working, it produces periodically changing bending and torsional stress, which bears the force transmitted from the connecting rod, converts it into torque and outputs it through the crankshaft and drives other accessories on the engine to work. During the actual operation of the engine, the crankshaft is subjected to constantly changing gas pressure, inertial force and moment, and bears the combined load of bending and torsion. Alternating stresses such as bending, torsion, shearing, tension and compression are generated in each part, resulting in higher temperature and wear. Due to the importance of the crankshaft and the complexity of its working con...

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