CN108300949B

CN108300949B - Method for orientationally distributing bundled bainite in steel

Info

Publication number: CN108300949B
Application number: CN201810143882.5A
Authority: CN
Inventors: 张欣; 赵旭; 刘庆锁
Original assignee: Tianjin University of Technology
Current assignee: Tianjin University of Technology
Priority date: 2018-02-12
Filing date: 2018-02-12
Publication date: 2020-01-17
Anticipated expiration: 2038-02-12
Also published as: CN108300949A

Abstract

A method for orientationally distributing bundled bainitic elements in steel. The steel billet smelted by the medium-frequency vacuum induction furnace is cast into a steel ingot, and then the steel ingot is forged into a plate at high temperature. Heating the steel to 1000-: c is 0.84 wt.% to 0.90 wt.%; si 1.34-1.45 wt.%; mn from 0.35 wt.% to 0.40 wt.%; cr is 0.95 wt.% to 1.10 wt.%; p <0.02 wt.%; s <0.02 wt.%; the balance being Fe. The invention has the characteristics of low cost, short period, simple process, high production efficiency and the like. The tensile strength of the prepared bundle bainite steel reaches 1700-2100MPa, and the bundle bainite steel can be applied to the fields of engineering machinery, roads, bridges and the like.

Description

Method for orientationally distributing bundled bainite in steel

Technical Field

The invention belongs to the technical field of metal materials, and particularly relates to bainite steel and a preparation method thereof.

Background

Bain and davenport obtained a bainitic structure through medium temperature isothermal transformation in the last 30 th century. Since then, bainite structures of various morphologies have been discovered by various researchers. Greatly promotes the practical application of the bainite steel in engineering. In 2002, Bhadeshia et al changed the chemical composition of steel to obtain bundled bainite, so that the steel material obtained excellent combination of strength, toughness and ductility, and further raised the enthusiasm of low-temperature bainite research. However, the medium temperature isothermal time is too long and the production efficiency is too low, so that the beam bainite steel is difficult to be industrially applied on a large scale.

Disclosure of Invention

The present invention aims to overcome the above-mentioned disadvantages of the prior art and to produce a beam bainite steel having an orientation distribution characteristic by using a temperature gradient field. The method has the advantages of simple production process, short period and low production cost, and the prepared bundled bainite steel has excellent mechanical properties.

Technical scheme of the invention

A bundled bainite steel with orientation distribution is obtained through a temperature gradient field, and the bundled bainite steel comprises the following chemical components in percentage by mass: c is 0.84 wt.% to 0.90 wt.%; si 1.34-1.45 wt.%; mn from 0.35 wt.% to 0.40 wt.%; cr is 0.95 wt.% to 1.10 wt.%; p <0.02 wt.%; s <0.02 wt.%; the balance of Fe and inevitable impurities.

The invention provides a method for orientationally distributing beam bainite in steel, which comprises the following steps:

(1) casting the steel billet containing the components smelted by the medium-frequency vacuum induction furnace into a steel ingot, and then forging the steel ingot into a plate at the high temperature of 1050-; the plate was cut into steel having a thickness of 5-10mm and a length and width of 50 mm.

(2) Heating the steel to 1000-1050 ℃, preserving heat for 20-30min, cooling the oil to 240-260 ℃, preserving heat for 20-30min, then cooling the oil to room temperature, and preparing the steel with the beam bainite with orientation distribution characteristics through a temperature gradient field formed in the steel during cooling.

According to the invention, a large temperature gradient is formed in the thickness direction of the sample through a thin sample, so that a large comparative driving force is provided in the thickness direction, the nucleation rate of the bundled bainite can be increased, the number of bundled bainite can be increased, and the bundled bainite has the characteristic of orientation distribution. This greatly increases the mechanical properties of the strand bainite steel.

The invention has the advantages and beneficial effects that:

1. with a thinner thickness, a larger temperature gradient is formed in the thickness direction when the steel material undergoes medium temperature isothermal. Under the action of a larger temperature gradient field, a large phase transformation driving force can be obtained when the beam bainite structure undergoes thermal transformation, so that the beam bainite structure has a large nucleation rate and has the characteristic of orientation distribution. Greatly improves the mechanical property of the beam bainite steel and improves the production rate of the beam bainite steel.

2. The beam bainite steel formed under the action of large temperature gradient field has good mechanical performance and tensile strength up to 1700-2100 MPa.

3. The medium-temperature isothermal time of the bundle bainite is short under the action of the temperature gradient field, the production efficiency can be improved, and the cost can be reduced.

4. Simple production process and wide application prospect. Can be widely applied to the fields of highway, bridge, marine facility shipbuilding and the like.

Drawings

FIG. 1 is a metallographic photograph of a sample obtained in example 1 of the present invention, and the orientation arrangement of bundled bainite can be observed.

FIG. 2 is a metallographic photograph of a sample obtained in example 2 of the present invention, and it is observed that the orientation arrangement of bundled bainite is characteristic.

Detailed Description

Example 1:

smelting the high-carbon silicon-containing steel by using a vacuum induction furnace, wherein the high-carbon silicon-containing steel comprises the following chemical components in percentage by mass: c is 0.88 wt.%; si 1.36 wt.%; mn 0.38 wt.%; cr 1.01 wt.%; p <0.02 wt.%; s <0.02 wt.%; the balance being Fe.

The melted steel ingot having the above-described contents of components is forged into a plate at a high temperature of 1050 ℃. The plate was processed by wire cutting into steel having a thickness of 5mm and a length and width of 50 mm. The steel is heated to 1000 ℃, kept warm for 20min, cooled to 240 ℃, kept warm for 20min and then cooled to room temperature by water. The tensile strength of the prepared steel is 2100 MPa. FIG. 1 is a metallographic structure photograph of orientation-aligned bundle bainite obtained by subjecting the high carbon silicon steel of the present invention to the above experimental conditions.

Example 2:

smelting the high-carbon silicon-containing steel by using a vacuum induction furnace, wherein the high-carbon silicon-containing steel comprises the following chemical components in percentage by mass: c is 0.89 wt.%; si 1.39 wt.%; mn 0.36 wt.%; cr is 0.96 wt.%; p <0.02 wt.%; s <0.02 wt.%; the balance being Fe.

And forging the smelted steel ingot with the component content at a high temperature of 1080 ℃ to form a plate. The plate was processed by wire cutting into steel having a thickness of 7mm and a length and width of 50 mm. The steel is heated to 1020 ℃, the temperature is kept for 30min, the oil is cooled to 260 ℃, the temperature is kept for 30min, and then the water is cooled to the room temperature. The tensile strength of the prepared steel was 1950 MPa. FIG. 2 is a metallographic structure photograph of orientation-aligned bundle bainite obtained by subjecting the high carbon silicon steel of the present invention to the above experimental conditions.

Claims

1. A bundled bainite steel with orientation distribution is obtained through a temperature gradient field, and is characterized in that the bundled bainite steel comprises the following chemical components in percentage by mass: c is 0.84 wt.% to 0.88 wt.%; si 1.34-1.45 wt.%; mn from 0.35 wt.% to 0.40 wt.%; cr is 0.95 wt.% to 1.10 wt.%; p <0.02 wt.%; s <0.02 wt.%; the balance of Fe and inevitable impurities;

the method for obtaining the beam bainite steel with orientation distribution through the temperature gradient field comprises the following steps:

(1) casting molten steel of the chemical components smelted by the medium-frequency vacuum induction furnace into a steel ingot, and then forging the steel ingot at 1050 & lt 1100 & gt to form a plate; cutting the plate into steel samples with the thickness of 5-10mm and the length and width of 50mm by using a wire;

(2) heating the steel sample to 1000-1050 ℃, preserving heat for 20-30min, cooling the oil to 240-260 ℃, preserving heat for 20-30min, then cooling the oil to room temperature, and preparing the steel with the beam bainite structure with orientation distribution characteristics through a temperature gradient field formed in the steel sample during cooling.

2. A method for orientationally distributing bundled bainite in steel is characterized by comprising the following steps:

(1) casting molten steel containing the components of claim 1 smelted by a medium-frequency vacuum induction furnace into a steel ingot, and then forging the steel ingot into a plate at the high temperature of 1050-; cutting the plate into steel samples with the thickness of 5-10mm and the length and width of 50mm by using a wire;