Steel for cold forging of universal joint fork of passenger car and manufacturing method of steel

Abstract

The invention relates to steel for cold forging of a universal joint fork of a passenger car and a manufacturing method of the steel. The steel comprises the following chemical components in percentage by mass: 0.04 to 0.10 percent of C, 0.01 to 0.12 percent of Si, 0.40 to 0.60 percent of Mn, less than or equal to 0.015 percent of P, 0.020 to 0.035 percent of S, less than or equal to 0.10 percent of Cr, less than or equal to 0.10 percent of Ni, less than or equal to 0.10 percent of Cu, less than or equal to 0.02 percent of Mo, 0.020 to 0.050 percent of Al, 0.007 to 0.009 percent of N and the balance of Fe and inevitable impurity elements. The texture of the steel is ferrite and pearlite, and the spheroidization rate of the pearlite is larger than or equal to 85%. The production process route comprises the steps of molten iron pretreatment, primary smelting in a converter, refining, continuous casting, continuous casting billet cooling, continuous casting billet heating, rolling, cooling, spheroidizing annealing and lathing. Taking a bar with the diameter phi of 20-40 mm as an example, the surface hardness is smaller than or equal to 110 HV30; Rp0.2 is smaller than or equal to 280 MPa, Rm is smaller than or equal to 360 MPa, the ductility A5 is larger than or equal to 40%, the percentage reduction of area Z is larger than or equal to 75%, and a product has excellent plasticity and low deformation resistance and is steel for cold forging with ideal performance.

Description

technical field [0001] The invention belongs to the technical field of iron-based alloys, and in particular relates to a steel suitable for cold forging and a manufacturing method thereof. Background technique [0002] The universal joint fork is a key component used in the steering system of passenger cars. At present, there are three main production methods: ①casting; ②hot forging; ③cold forging. Castings are prone to trachoma, easy to break and unsafe, have great quality defects, and are not easy to be detected. The disadvantage of hot forging is mainly that the dimensional accuracy of the formed part is low, and subsequent processing is required, which destroys the fibers inside the metal. Cold forging refers to the direct production of products close to the final shape of the part at room temperature, even to provide qualified finished parts. [0003] Features of cold forging parts: ①Improve the structure and performance, the grain structure becomes thinner, the densi...

AI Technical Summary

Problems solved by technology

Castings are prone to sand holes, easy to break and unsafe, have great quality defects, and are not easy to be detected

The disadvantage of hot forging is mainly that the dimensional accuracy of the formed part is low, and subsequent processing is required, which destroys the fibers inside the metal.

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