Heat treatment method for improving medium-carbon non-quenched and tempered steel connecting rod cracking performance

Abstract

The invention provides a heat treatment method for improving medium-carbon non-quenched and tempered steel connecting rod cracking performance, and belongs to the field of heat treatment of metals. The method is the heat treatment method of a medium-carbon non-quenched and tempered steel connecting rod of which the components are set, a medium-carbon non-quenched and tempered steel connecting rod blank of which the components are set is placed in a vacuum induction heating furnace, the vacuum degree of the heating furnace ranges from 0.1 Pa to 1.0 Pa, the heating temperature in the furnace ranges from 1150 DEG C to 1200 DEG C, the heat preservation time ranges from 20 min to 40 min, microalloy elements in the steel are fully dissolved in austenite, and it is guaranteed that a low oxidizing or non-oxidizing decarburizing reaction occurs on the surface of the connecting rod; the cooling speed of the medium-carbon non-quenched and tempered steel connecting rod blank come out of the furnace is controlled to be 8-12 DGE C / second through a wind-cooling device, after the medium-carbon non-quenched and tempered steel connecting rod blank is cooled to be at 300-400 DEG C, the medium-carbon non-quenched and tempered steel connecting rod blank is naturally cooled to be at the room temperature in a slow cooling device, the microalloy elements dissolved in the austenite are separated out in a dispersion mode, and meanwhile the ferrite grain size and the content of the pearlite are increased; therefore, tensile strength and cracking performance of the medium-carbon non-quenched and tempered steel connecting rod are improved, and standard requirements of an automobile engine cracking connecting rod are met.

Description

technical field [0001] The invention discloses a heat treatment method for improving the expansion breaking performance of a medium-carbon non-quenched and tempered steel connecting rod, which belongs to the field of metal heat treatment, and in particular relates to a heat treatment method for steel used for expansion breaking connecting rods of automobile engines. Background technique [0002] As a new technology superior to the traditional connecting rod processing technology, the engine connecting rod expansion process has been widely used in the manufacturing of connecting rods. The material of the connecting rod that adapts to the expanding process of the connecting rod not only affects the performance and machinability of the connecting rod product, but also determines the crackability and section quality, which plays a key role in the expanding process. Therefore, the material of the bursting connecting rod is generally required to have high strength, small plastic d...

AI Technical Summary

Problems solved by technology

Its advantage is that for the non-quenched and tempered steel with less microalloy content, it can not only improve the performance appropriately, but also reduce the production cost; but for the non-quenched and tempered steel connecting rod containing a large amount of microalloy elements such as V, Nb, Ti, etc. Rapid cooling at the final temperature cannot cause the maximum amount of solid-solution microalloy phases to precipitate in the steel, so the effective role of microalloy elements cannot be brought into play.

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