High strength level non-quenched-tempered steel bar for manufacturing of engine rocker and manufacture method thereof

Abstract

The invention relates to a high strength level non-quenched-tempered steel bar for manufacturing of an engine rocker. The high strength level non-quenched-tempered steel bar for the manufacturing of the engine rocker consists of chemical components of 0.42-0.49% of C, 0.40-0.80% of Si, 0.80-1.50% of Mn, P<=0.040%, 0.035-0.075% of S, 0.10-0.30% of Cr, 0.01-0.25% of Ni, Mo<=0.08%, Al<=0.015%, Ti<0.010%, 0.13-0.20% of V, 0.012-0.022% of N, and the balance being Fe and unavoidable impurity elements. The product is of hot rolling round steel bar form. After the steel bar is forged into the rocker and cooled in air, a rocker forging can achieve following mechanical properties: yield strength>=800MPa, tensile strength>=1000MPa, ductility>=12%, area reduction rate>=38% and harness>=290HB. The metallographic structure of the rocker forging is tiny ferrite and pearlite structure. MnS inclusions and composite inclusions thereof are distributed in the metallographic structure. The high strength level non-quenched-tempered steel bar is a non-quenched-tempered medium carbon round steel high in hardness, easy to cut, and high in surface quality, and completely meets forging requirements of the engine rocker.

Description

technical field [0001] The invention belongs to the field of metallurgy, in particular to a high-strength non-quenched and tempered round steel. Background technique [0002] Most of the raw materials traditionally used to make engine rocker arms are 45 steel, 40Cr, 42CrMo and other alloy structural steels. After forging such alloy structural steel bars into engine rocker arm rough forgings, they must be quenched and tempered. In order to make the mechanical properties of the parts meet the requirements of use. When high-strength rocker arms are to be manufactured, the traditional alloy structural steels such as 40Cr and 42CrMo may sometimes have unqualified performance after quenching and tempering heat treatment. [0003] The main process flow of using alloy structural steel to manufacture engine rocker arm is: [0004] Raw material cutting-heating-forging-cooling-machining-quenching and tempering heat treatment-subsequent processing. [0005] In this manufacturing proc...

AI Technical Summary

Problems solved by technology

[0005] In this manufacturing process, due to the quenching and tempering treatment (quenching and tempering) of the parts, there are two problems that cannot be avoided; one is the quality problems (such as deformation, cracking, performance, etc.) of the parts during the heat treatment process. Unqualified); second, energy consumption, oxidation and burning of raw materials, consumption of heat treatment materials, pollution to the environment, and impact on personal safety will occur during the heat treatment process.

The end result of these two problems is to increase the manufacturing cost of the parts and have adverse effects on nature and society

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