JPH02179844A - Wear resistant alloy steel - Google Patents

Abstract

PURPOSE:To improve the hardness, toughness, and tempering softening resistance of the steel by increasing Si content in a steel, controlling Mn content, and specifying respective contents of Cr, B, and N. CONSTITUTION:A wear resistant alloy steel has a composition consisting of, by weight ratio, 0.30-0.40% C, 1.0-2.0% Si, 0.40-1.0% Mn, 0.80-2.00% Cr, 0.0005-0.0030% B, <=0.0100% N, and the balance Fe with impurity elements. Further, 0.03-0.30% Ti is incorporated to the above composition, if necessary. In this steel, the hardness and tempering softening resistance of matrix are improved by increasing Si content and also toughness and hardenability are improved by controlling Mn content and incorporating a proper quantity of B, and further, earth and sand wear resistance are particularly improved in this alloy. This steel can be used, e.g. for bucket tooth for power shovel.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to wear-resistant alloy steel, and more specifically, it has excellent hardness, impact resistance, and temper softening resistance, and is used for bucket teeth for power shovels, etc. It relates to wear-resistant alloy steels, especially earth and sand wear-resistant steels.

[Conventional technology]

Conventionally, as earth and sand abrasion resistant steel, C0.
31-0.36%, Sin, 15-0.35%, BO,
Steel containing 0.0005% to 0.0030% (referred to as conventional steel) is known.

[The problem that the invention aims to solve]

As a steel for earth and sand wear resistance, the surface hardness and core toughness are approximately 200 to 300℃ when used in the bucket teeth, etc.
temper softening resistance is required. The required characteristic values for the above applications include hardness H, 5
30 or more, an impact value of 6 gfm/cm" or more, and better earth and sand wear resistance than the above-mentioned conventional steels.

The conventional steel mentioned above is used for this purpose, but the impact value
It does not fully satisfy soil and sand abrasion resistance. Therefore, it is desired to develop a wear-resistant alloy steel with improved performance.

In view of the above-mentioned viewpoint, the inventor of the present invention has conducted intensive studies, and as a result, has found the optimum chemical composition of wear-resistant alloy steel (alloy component), and has completed the present invention. An object of the present invention is to provide a wear-resistant alloy steel with excellent hardness, toughness, and resistance to temper softening, particularly an earth and sand wear-resistant alloy steel.

[Means to solve the problem]

The first invention steel has a CD of 30 to 040% by weight.
, S i 1. (1-2.0%, Mn 0.40~
1.0%, Cr0.80-2.00%, B 0.000
It is characterized by containing 5 to 0.0030% and 0.0100% or less of N, with the remainder consisting of Fe'Ml and impurity elements. This increases the Si content, improves the hardness of the base material and improves the resistance to temper softening, and improves the Mn content compared to conventional steel.
By regulating the content and incorporating an appropriate amount of B to improve toughness and hardenability, wear resistance, particularly earth and sand wear resistance, is improved.

The second invention steel further contains 0.03 to 0.30% Ti in the chemical composition of the first invention steel to generate TIC and further improve the earth and sand wear resistance.

Next, the reason for limiting the chemical composition of the steel of the present invention will be explained below.

C is an element that secures the hardness necessary for bucket teeth etc. and improves wear resistance by forming carbides, and is contained in an amount of 0.30% or more to ensure quenching and tempering hardness H, 530 or more. It is necessary to do so. However, if the content increases, the core becomes too hard and the toughness decreases, so the upper limit was set at 0.40%.

Si is an element that increases the strength of the base material, improves resistance to temper softening, and improves earth and sand wear resistance, and must be contained in an amount of 1.0% or more to ensure this effect. However, as the content increases, the toughness decreases, so the upper limit was set at 2.0%.

Mn is an element necessary to ensure hardenability and hardness, and its effect is 5f! In order to maintain this, it is necessary to contain 0°40% or more. However, as the content increases, the toughness decreases, so the upper limit was set at 10%.

Cr is an element necessary to ensure hardenability and improve wear resistance by forming carbides, and must be contained in an amount of 0.80% or more to ensure this effect.

However, if the content exceeds 2.00%, the quenching temperature will rise, making the quenching work complicated, and the hardenability will be saturated, resulting in little improvement in the effect, so the upper limit was set at 2.00%.

Like Cr, B is an element necessary to ensure hardenability, and in order to ensure this effect, it is necessary to contain it in an amount of 0°0005% or more. Moreover, this element is economical because it exhibits its effect even when added in a trace amount. But 0.0Q3
Even if the content exceeds 0%, the hardenability will be saturated and the effect will not be improved much, so the upper limit was set at 0.0030%.

Since N combines with B and impairs the hardening effect of B, its content must be regulated, and the upper limit was set at 0°0100%.

T1 contained in the second invention steel is an element useful for improving earth and sand wear resistance, and in order to ensure the effect, T1 is
．． It is necessary to contain 0.3% or more. But 0.30%
If the content exceeds 0.3%, the effect will be saturated and there will be little improvement in the effect, so the upper limit was set at 0.30%.

〔Example〕

Hereinafter, the steel of the present invention will be specifically explained in comparison with conventional steel and comparative steel.

First invention steel (A-D), second invention steel (E, F), comparison 8
The chemical compositions of (G to K) and conventional steel (L) are shown in Table 1.

Performance evaluations of hardness, impact value, and earth and sand abrasion resistance were conducted for the above eight steels, and the results are shown in Table 2. In addition, each evaluation method is as follows. The test materials in Table 1 were heated to 920°C.
× Quenching (WQ) after heating for 30 minutes, then 250℃×
After tempering for 2 hours, hardness etc. were measured.

The impact value was measured by preparing a JIS No. 3 U-notch type Charvy test piece. Earth and sand wear resistance was evaluated using an index with conventional steel set at 100.

Compare! f! As is clear from Table 2, IG has a hardness of HV517 and an earth and sand abrasion resistance of 106, making it inferior as a wear-resistant alloy. Comparative steel H has a hardness of Hv526, which is almost satisfactory, but its earth and sand abrasion resistance is as low as 102 in Tables 1 and 2, making it inferior as a wear-resistant alloy. Comparative steel (3) has excellent hardness and earth and sand abrasion resistance, but has a low impact value of 4.3 gfm/cm' and has a problem in toughness. Comparative steel J does not have sufficient hardenability (hardness is low at Hv522 and is inferior as a wear-resistant alloy.
Hardenability is insufficient, hardness is low at Hv513, and earth and sand wear resistance is low at +05, making it inferior as a wear-resistant alloy.

Conventional nL has an impact value of 4 or 5 Kgfm/am”
It is extremely small, and its earth and sand abrasion resistance is as low as 100, making it inferior as a wear-resistant alloy.

On the other hand, the steels A-F of the present invention have a hardness of H, 5, 34 to 55.
7. Opposition! l1IJti is 6, 4-7, 5 Kg
fm/cm' Earth and sand wear resistance is excellent at 118 to 141, and all alloys satisfy the required characteristics as wear-resistant alloy steels.

〔Effect of the invention〕

The 11th and 2nd invention steels all have a higher Sl content, a lower Mn content, and a C
Since it is characterized by containing r, compared to conventional steel, it maintains hardness while improving temper softening resistance and toughness, significantly improving impact resistance, and especially improving earth and sand abrasion resistance. , is very well balanced. Therefore, the steel of the present invention is useful as it has the characteristics required by the industry for bucket teeth for power shovels and the like.

Furthermore, the second invention steel further includes T in the chemical composition of the first invention steel.
1, the earth and sand abrasion resistance is further improved.

Patent applicant: Aichi Steel Co., Ltd. Representative Patent Attorney Kiyomichi Kojima

Claims (2)

[Claims] (1) Weight ratio: C0.30-0.40%, Si1
．． 0-2.0%, Mn0.40-1.0%, Cr0.8
A wear-resistant alloy steel characterized by containing 0 to 2.00% of B, 0.0005 to 0.0030% of B, and 0.0100% or less of N, with the remainder consisting of Fe and impurity elements. (2) C0.30-0.40% by weight, Si1
．． 0-2.0%, Mn0.40-1.0%, Cr0.8
0 to 2.00%, B 0.0005 to 0.0030%, and N 0.0100% or less, and further contains Ti 0.03 to 0.0100%.
A wear-resistant alloy steel characterized by containing 0.30%, with the remainder consisting of Fe and impurity elements.