High-strength toughness non-quenched and tempered steel wire rod and its preparation method

Abstract

The invention discloses a high-toughness non-tempering steel wire rod and a preparation method thereof. The preparation method comprises processes of heating, rolling and cooling. The steel wire rod comprises the following chemical components in percentages by weight: 0.22-0.31% of C, 1.20-1.55% of Mn, 0.25-0.70% of Si, less than or equal to 0.015% of P, less than or equal to 0.015% of S, 0.10-0.40% of Cr, 0.05-0.20% of V, 0.010-0.050% of Ti, 0.010-0.025% of N, 0.010-0.050% of Al, less than or equal to 0.25% of Cu, less than or equal to 0.20% of Ni, less than or equal to 0.10% of Mo, and the balance of Fe and inevitable impurity elements. The microstructure of the steel wire rod obtained by the method consists of ferrite and pearlite, the grain size is greater than level 7, the tensile strength is 750-850 MPa, reduction of area is greater than or equal to 40%, and impact toughness AkV is greater than or equal to 110J; strength and impact toughness are relatively high, and requirements of downstream customers on production of parts of automotive steering systems can be met; and meanwhile, quenching and tempering are omitted, and production and manufacturing costs are reduced.

Description

technical field [0001] The invention relates to a non-quenched and tempered steel, in particular to a high-strength toughness non-quenched and tempered steel wire rod and a preparation method thereof. Background technique [0002] Automobile steering system components (such as ball studs, etc.) are often subjected to certain collision and impact loads during service, so they are required to have high strength and impact toughness at the same time. At present, 45# steel or 40Cr quenched and tempered steel is mainly used. The production cost is high, and the quenching and tempering process is prone to deformation, cracking, decarburization and other defects. [0003] Non-quenched and tempered steel is a new type of energy-saving, green and environmentally friendly material that omits the quenching and tempering treatment process. The tensile strength of the wire rod is increased through microalloying to achieve the purpose of omitting the subsequent quenching and tempering hea...

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Problems solved by technology

[0004] Notification number CN1332054C announced "A kind of non-quenched and tempered carbon structural steel and its manufacturing method", which improves the strength of non-quenched and tempered steel by adding microalloying elements such as V and controlled rolling and controlled cooling process on the basis of 45# steel. Insufficient toughness, the rolled product is a bar, the tensile strength is 690-760MPa, the impact toughness value is 43-53J, and the impact toughness is still low

[0005] The publication number is CN104593671A, which discloses "A High-Strength and Toughness Non-Quenched and Tempered Steel Suitable for Composite Forging and Forming". The forging of this non-quenched and tempered steel has high strength and toughness, but its chemical composition is added with precious metals such as Nb and rare earth. Elements will increase the cost; and it is mainly processed into forgings through the composite forging forming process, and the process is relatively complicated

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