A V microalloyed high-strength toughness bainite non-quenched and tempered steel and its controlled forging and controlled cooling process and production process

Abstract

The invention discloses a V microalloyed high-strength toughness bainitic non-quenched and tempered steel and its controlled forging and controlled cooling process and production process. The V microalloyed high-strength and toughness bainitic non-quenched and tempered steel includes the following weight percentages Chemical composition: C 0.20‑0.30%, Si 0.20‑0.40%, Mn 1.90‑2.10%, P≤0.010%, S 0.030‑0.050%, Cr 0.40‑0.60%, V 0.10‑0.20%, Ti 0.015‑0.025%, Ni≤0.20%, Mo≤0.20%, Al 0.020‑0.045%, N 60‑120ppm, the rest are Fe and unavoidable impurity elements, and Ti×N≤0.00016; compared with 42CrMo quenched and tempered steel, this steel type has an Under the premise that the cost of raw materials is equivalent, the fatigue performance is equivalent, which can omit the heat treatment and tempering process for forging enterprises, reduce the manufacturing cost of parts and reduce energy consumption, and can be used to replace 42CrMo quenched and tempered steel to manufacture parts that require high strength and toughness. part.

Description

technical field [0001] The invention belongs to the technical field of alloy structural steel, and in particular relates to a V microalloyed high-strength toughness bainite non-quenched and tempered steel and its controlled forging and controlled cooling process and production process. Background technique [0002] Traditional non-quenched and tempered steels generally add trace elements such as V, Nb, Ti to medium carbon (0.2-0.5% C) steel, and carry out controlled rolling (forging) and controlled cooling, so that V, Nb, Ti and other elements Precipitation of carbides and nitrides realizes the strengthening effect and obtains mechanical properties similar to quenching and tempering treatment, thereby eliminating the need for quenching and tempering treatment. In the cooling process after deformation, the precipitation strengthening effect of the carbonitride of V element is the strongest, and its strengthening effect is at a high level in a wide temperature range and does n...

AI Technical Summary

Problems solved by technology

Due to the low phase transformation temperature, the diffusion of alloying elements is inhibited during the phase transformation process, which makes it difficult to precipitate carbides of pinning dislocations, resulting in a high density of mobile dislocations in bainitic non-quenched and tempered steels, resulting in bainitic non-quenched and tempered steels. The yield strength of quenched and tempered steel is relatively low (≤0.70) under the general controlled forging and controlled cooling process conditions, which reduces the fatigue performance of bainite non-quenched and tempered steel

[0005] In order to improve the yield strength ratio of bainitic non-quenched and tempered steels, many bainitic non-quenched and tempered steels are tempered above 400°C. low steel strength

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