阅读说明：本技术 一种耐磨钢及其冶炼方法 (Wear-resistant steel and smelting method thereof ) 是由 杨名旗 于 2018-06-27 设计创作，主要内容包括：本发明涉及一种耐磨钢及其冶炼方法,该耐磨钢包括碳、硅、锰、铌、铬、磷、氧、硫及铁等元素,通过铁水预处理、转炉冶炼和炉外精炼及常规轧制步骤冶炼成该耐磨钢。在冶炼中通过微合金化和稀土处理等方式控制合金成分,使用该耐磨钢制造的汽车结构件的屈服强度、抗拉强度、疲劳寿命、耐磨性能等指标均远高于现有的钢板,并且还有进一步减薄的空间,可减轻机动车的质量,进而实现节能。(The invention relates to wear-resistant steel and a smelting method thereof, wherein the wear-resistant steel comprises elements such as carbon, silicon, manganese, niobium, chromium, phosphorus, oxygen, sulfur, iron and the like, and is smelted through the steps of molten iron pretreatment, converter smelting, external refining and conventional rolling. Alloy components are controlled in modes of micro-alloying, rare earth treatment and the like in smelting, indexes such as yield strength, tensile strength, fatigue life, wear resistance and the like of an automobile structural part manufactured by using the wear-resistant steel are far higher than those of an existing steel plate, and a space for further thinning is provided, so that the mass of a motor vehicle can be reduced, and energy conservation is realized.)

1. The wear-resistant steel is characterized by comprising the following materials in percentage by weight: 0.10 to 0.15 percent of carbon; 0.10 to 0.30 percent of silicon; 1.40 to 1.80 percent of manganese; 0.03 to 0.10 percent of niobium; phosphorus is less than or equal to 0.015 percent; oxygen is less than or equal to 0.004 percent, and sulfur is less than or equal to 0.005 percent; 0.40 to 0.70 percent of chromium, and the balance of iron and inevitable impurities.

2. Method for smelting a wear resistant steel according to claim 1, characterized by the steps of:

pretreating molten iron: adding a desulfurizing agent into the molten iron pretreatment device, and transferring the molten iron into a converter for smelting when the content of sulfur in the molten iron is less than or equal to 0.005 percent;

smelting in a converter: blowing oxygen to the desulfurized molten iron for smelting, and slagging by using lime and light burned dolomite, wherein the oxygen blowing time is 14-18 minutes, and the tapping temperature is kept between 1670-1690 ℃;

refining outside the furnace: the molten steel smelted by the converter is sent into an LF ladle refining furnace, niobium, manganese, silicon, chromium and the like are added into the steel according to requirements to adjust the alloy content in the steel, simultaneously, a deoxidizer is added, then, oxygen is blown into the ladle refining furnace from the top of the ladle refining furnace, argon or nitrogen is blown into the ladle refining furnace from the bottom of the ladle refining furnace, and the wear-resistant steel is obtained by conventional rolling after casting.

3. The method according to claim 2, wherein the desulfurizing agent is composed of magnesium powder and lime powder, and the weight ratio of the magnesium powder to the lime powder is 1: 2.5-3.5.

4. The method according to claim 2, wherein the tapping step of the converter includes a slag amount of 5 kg or less per ton of steel.

5. The method as set forth in claim 2, wherein the deoxidizing agent added in the external refining step is a deoxidizing agent composed of a silicon aluminum barium strontium calcium composite material, and the adding amount of the deoxidizing agent is 350-450 kg per furnace steel (150 tons steel).

6. The method of claim 2, wherein the furnace clearance height is maintained between 200mm and 300mm during the external refining step.

Technical Field

The invention relates to wear-resistant steel and a method for smelting the wear-resistant steel.

Background

The dead weight of the mine locomotive is in direct proportion to the oil consumption, namely the heavier the mine locomotive, the larger the oil consumption, and the lightening of the weight of the locomotive body is one of the most effective means for realizing wear resistance, weight reduction and energy conservation. The bottom plate and the side plates of the carriage are important bearing parts for bearing ore and transporting coal, and the carriage has the characteristic of light weight while ensuring sufficient bearing capacity so as to meet the requirement of low carbon. In the prior art, materials for manufacturing the floor and the side plates of the carriage comprise a manganese plate, a heat-treated steel plate and the like, the manganese plate is low in price, but the manganese plate is insufficient in strength, so that the fatigue life is low, the heat-treated steel plate is high in price, the production process is complex, and the popularization and the use are not facilitated, so that the materials for the floor and the side plates of the carriage are still to be further developed.

The Chinese patent No. 101033521A discloses a new steel for manufacturing a steel plate of an automobile brake pad and a production method thereof. The chemical components of the steel are C: 0.24-0.30%; si 0.17-0.35%; 0.50 to 0.95 percent of Mn; p is less than or equal to 0.025 percent; s is less than or equal to 0.018; 0.010-0.030% of Als and the balance of iron. The smelting method of the steel is to prepare the finished product steel through the steps of blast furnace ironmaking, converter steelmaking, LF furnace refining, sheet billet continuous casting, progressive heating furnace heating, rough rolling, hot curling, fine rolling and the like. The carbon content in the steel has great influence on the quality of the steel, and the wear resistance of the steel is increased along with the increase of the carbon content of the steel, but the plasticity of the steel plate is reduced; in addition, it is further investigated whether the contents of other elements, such as silicon, manganese, nitrogen, and sulfur, meet the requirements of wear-resistant steels. With the basic and secondary effects of the microalloying elements in the steel, the concept of austenite adjustment is provided, and the microalloying elements niobium and chromium are intentionally and controllably added to develop new steel types with better performance. For example, niobium can refine grains, so that NbC strain-induced refraction during hot rolling of steel can hinder recovery and recrystallization of deformed austenite, so as to improve the toughness of the steel, chromium can improve hardenability, and Cr has affinity with carbon greater than that of iron and manganese, and can replace part of iron to form composite cementite (Fe, Cr) 3C. The complex carbide (Cr, Fe) 7C3 of chromium and (Cr, Fe) 23C6 have obvious influence on the performance of steel, especially can improve the wear resistance of the steel, and 0.01-0.04% of rare earth is added into the steel, so that the strength and the impact toughness of the steel are improved to different degrees. However, up to now, no technical suggestion of containing niobium and chromium at the same time has been found in the aspect of wear-resistant steel.

Disclosure of Invention

The invention aims to provide the wear-resistant steel which utilizes niobium and chromium microalloying and omits a heat treatment mode to ensure that the wear-resistant steel meets the requirements of mechanical properties and service performance.

Another object of the present invention is to provide a method for smelting wear-resistant steel by using rare earth treatment and effective control of alloy composition.

The wear-resistant steel provided by the invention comprises the following materials in percentage by weight: 0.10 to 0.15 percent of carbon; 0.10 to 0.30 percent of silicon; 1.40 to 1.80 percent of manganese; 0.03 to 0.10 percent of niobium; phosphorus is less than or equal to 0.015 percent; oxygen is less than or equal to 0.004 percent, and sulfur is less than or equal to 0.005 percent; 0.40 to 0.70 percent of Cr0.40 percent, and the balance of iron and inevitable impurities. Wherein, niobium can refine crystal grains and promote the formation of acicular ferrite, if the content of niobium is less than 0.005 percent, the formation of acicular ferrite is not favorable, and if the content is more than 0.10 percent, the welding performance of the wear-resistant steel can be directly influenced; manganese has the functions of improving the strength and the toughness, reducing the ductile-brittle transition temperature and improving the wear resistance in the wear-resistant steel; cr has a higher affinity for carbon than iron and manganese, and can replace a portion of iron to form complex cementite (Fe, Cr) 3C. The complex carbide (Cr, Fe) 7C3 of chromium and (Cr, Fe) 23C6 have obvious influence on the performance of steel, particularly the wear resistance of the steel can be improved, the carbon content in the steel determines the performance of the steel, the carbon content in the invention is only between 0.10 and 0.15 percent, so that the steel has good ductility, the yield strength and the tensile strength of the steel can be improved by adding niobium and chromium into the steel, and the wear resistance of the steel can be improved by increasing the carbon content.

The method for smelting the wear-resistant steel comprises the following steps:

pretreating molten iron: adding a desulfurizing agent into the molten iron pretreatment device, and transferring the molten iron into a converter for smelting when the content of sulfur in the molten iron is less than or equal to 0.005 percent;

smelting in a converter: blowing oxygen to the desulfurized molten iron for smelting, and slagging by using lime and light burned dolomite, wherein the oxygen blowing time is 14-18 minutes, and the tapping temperature is kept between 1670-1690 ℃;

refining outside the furnace: the molten steel smelted by the converter is sent into a ladle refining furnace, namely an LF furnace, niobium, manganese, silicon and chromium are added into the ladle refining furnace according to the estimated alloy content in the molten steel to adjust the alloy content in the steel, a deoxidizer is added at the same time, then oxygen is blown into the ladle refining furnace from the top of the ladle refining furnace, argon or nitrogen is blown into the ladle refining furnace from the bottom, and the molten steel is cast and matched with rare earth for treatment and then is rolled regularly to obtain the wear-resistant steel.

The desulfurizer consists of magnesium powder and lime powder, and the weight ratio of the magnesium powder to the lime powder is 1: 2.5-3.5.

In the step of smelting and tapping by the converter, the slag discharging amount is less than or equal to 5 kg of steel slag per ton of steel.

The deoxidizer added in the external refining step is a deoxidizer made of a silicon-aluminum-barium-strontium-calcium composite material, and the addition amount of the deoxidizer is 450 kilograms in addition to 350-450 kilograms in each furnace steel (150 tons of steel).

In the step of refining outside the furnace, molten steel top slag in the furnace is kept between 200mm and 300 mm.

The detection shows that the carriage bottom plate and the side plate which are 8.0mm and 10.0mm thick and are made of the wear-resistant steel have the yield strength of 560MPa, the tensile strength of 670MPa and Brinell hardness values of more than or equal to 200, the wear resistance test is carried out on an ML-100 abrasive wear testing machine, for comparison, SS400 is taken as a reference sample, and the test result shows that: the wear rate of the wear-resistant steel is lower than SS400, and the wear resistance is good.

The wear-resistant steel is mainly applied to heavy trucks with carrying capacity of more than 30 tons. The steel plate made of the wear-resistant steel has strong bearing capacity and high wear resistance, and the bottom and two sides of the carriage have very good deformation resistance, so that the original deformation-preventing support hanging part can be detached, and the quality of a motor vehicle is further reduced.

Drawings

FIG. 1 is a wear-resistant steel and a wear-resistant rate chart of a smelting method of the wear-resistant steel under the load conditions of 120-mesh sand paper and 21N.

Detailed Description

Referring to fig. 1, a graph of wear rate under load of 120-mesh sand paper and 21N is shown, the vertical axis of the graph represents wear rate/mg/M, the data show that the performance of the wear-resistant steel far exceeds that of the existing material, and further space is reduced, and energy can be saved by using the wear-resistant steel for a motor vehicle. Example 1:

firstly, carrying out desulfurization treatment on molten iron in a molten iron pretreatment device, namely adding a desulfurizing agent consisting of magnesium powder and lime powder into the molten iron, wherein the weight ratio of the magnesium powder to the lime powder is 1: 3, performing conventional detection, finishing the pretreatment process when the sulfur content in the molten iron is less than or equal to 0.005%, and pouring the molten iron into a converter for smelting; in the working procedure of converter smelting, lime and light burned dolomite are added into a converter for slagging, then oxygen is blown into the converter for 14 minutes, steel is tapped after the oxygen blowing working procedure is finished, the tapping temperature is kept at 1670 ℃, and the slag amount is less than or equal to 5 kilograms of steel slag per ton of steel; and then sending the molten steel into a ladle refining furnace, namely an LF furnace, adding niobium, manganese, silicon, chromium and the like into the ladle refining furnace according to the estimated alloy content in the molten steel to adjust the alloy content in the steel, simultaneously adding a deoxidizer, keeping the top slag of the molten steel in the furnace at 200-300mm, blowing oxygen into the ladle refining furnace from the top of the ladle refining furnace, blowing argon or nitrogen into the ladle refining furnace from the bottom, and casting and rare earth processing the molten steel to obtain the wear-resistant steel by conventional rolling. The wear-resistant steel comprises the following materials in percentage by weight: 0.13% of carbon; 0.18% of silicon; 1.57 percent of manganese; 0.04% of niobium; 0.50 percent of chromium; phosphorus is less than or equal to 0.012 percent; oxygen is less than or equal to 0.005 percent, and sulfur is less than or equal to 0.012 percent; the balance being iron and unavoidable impurities.