Abrasion resistant steel having excellent hardness and impact toughness and manufacturing method therefor

Abstract

One embodiment of the present disclosure provides an abrasion resistant steel having excellent hardness and impact toughness, and a manufacturing method therefor, the steel comprising, by wt %, 0.33-0.42% of C, 0.1-0.7% of Si, 0.6-1.6% of Mn, 0.05% or less of P, 0.02% or less of S, 0.07% or less of Al, 0.55-5.0% of Ni, 0.01-1.5% of Cu, 0.01-0.8% of Cr, 0.01-0.8% of Mo, 50 ppm or less of B, and 0.02% or less of Co, further comprising one or more selected from the group consisting of 0.02% or less of Ti, 0.05% or less of Nb, 0.05% or less of V and 2-100 ppm of Ca, and comprising the balance of Fe and other inevitable impurities, wherein C and Ni satisfy the following relation 1, and the microstructure comprises 95 area % or more of martensite and 5% or less of bainite (including 0%). [Relation 1] [C]×[Ni]≥0.231

Description

TECHNICAL FIELD[0001]The present disclosure relates to a high hardness abrasion resistant steel and a manufacturing method therefor, and more particularly, to a high hardness abrasion resistant steel which may be used for construction machinery, and the like, and a manufacturing method therefor.BACKGROUND ART[0002]As for construction machinery and industrial machinery used in many industrial fields such as construction, civil engineering, mining, and cement industries, since abrasion may occur severely due to friction in operation, it may be necessary to apply a material exhibiting abrasion resistance properties.[0003]Generally, as abrasion resistance and hardness of a thick steel sheet may be correlated with each other, it may be necessary to increase hardness in the thick steel sheet concerned, to be worn down. To secure stable abrasion resistance, it may be necessary to have uniform hardness from the surface of the thick steel sheet to the inside (around t / 2, t=thickness) of the ...

AI Technical Summary

Benefits of technology

[0011]According to an aspect of the present disclosure, an effect of providing an abrasion resistant steel having a thickness of 60 mm or less and having high hardness and excellent low-temperature toughness may be obtained.

[0012]In the description below, the present disclosure will be described in detail. The alloy composition of the present disclosure will be described first. The content of the alloy composition described below may be represented by weight %.

[0014]Carbon (C) may be effective in increasing strength and hardness in a steel having a martensite structure and may be effective for improving hardenability. To sufficiently secure the above-described effect, it may be preferable to add C by 0.33% or more. However, when the content thereof exceeds 0.42%, weldability and toughness may degrade, such that an additional heat treatment such as tempering may be inevitable. Therefore, in the present disclosure, it may be preferable to control the content of C to be 0.33-0.42%. A lower limit of the content of C may more preferably be 0.34%, even more preferably 0.35%, and most preferably 0.36%. An upper limit of the content of C may more preferably be 0.40%, even more preferably 0.39%, and most preferably 0.38%.

[0016]Silicon (Si) may be effective in improving strength according to deoxidation and solid solution strengthening. To obtain the above effect, it may be preferable to add Si by 0.1% or more. However, when the content thereof exceeds 0.7%, weldability may deteriorate, which may not be preferable. Therefore, in the present disclosure, it may be preferable to control the content of Si to be 0.1-0.7%. A lower limit of the content of Si may more preferably be 0.12%, even more preferably 0.15%, and most preferably 0.2%. An upper limit of the Si content may more preferably be 0.5%, even more preferably 0.45%, and most preferably 0.4%.

[0018]Manganese (Mn) may suppress ferrite formation and may effectively improve hardenability by decreasing Ar3 temperature, thereby improving strength and toughness of steel. In the present disclosure, to secure hardness of the thick steel material, it may be preferable to include Mn in an amount of 0.6% or more. When the content exceeds 1.6%, weldability may degrade. Therefore, in the present disclosure, it may be preferable to control the content of Mn to be 0.6-1.6%. A lower limit of the content of Mn may more preferably be 0.65%, even more preferably 0.70%, and most preferably 0.75%. An upper limit of the content of Mn may more preferably be 1.55%, even more preferably 1.50%, and most preferably 1.45%.

[0022]Sulfur (S) may deteriorate toughness of steel by forming an MnS inclusion in steel. Therefore, it may be preferable to control the content of S to be 0.02% or less by lowering the content as much as possible, but 0% may be excluded in consideration of the inevitably included amount. The content of S may more preferably be 0.01% or less, even more preferably 0.005% or less, and most preferably 0.003% or less.

Problems solved by technology

As for construction machinery and industrial machinery used in many industrial fields such as construction, civil engineering, mining, and cement industries, since abrasion may occur severely due to friction in operation, it may be necessary to apply a material exhibiting abrasion resistance properties.

However, to manufacture an extremely thick steel sheet, it may be necessary to add a greater amount of hardenability elements to secure hardenability in the center of the steel sheet, and as C and hardenability alloys are added in large amounts, manufacturing costs may increase, and weldability and low-temperature toughness may degrade, which may be problematic.