KR100256368B1 - Hypereutectoid high chrome carbide type alloy for built-up welding - Google Patents

Abstract

PURPOSE: Provided is a hyper-eutectic Cr-rich alloy of carbide-based having superior scratch resistance for overlay welding for the application to anti-abrasive structural member such as a dredging machine and a crush roll. CONSTITUTION: The hyper-eutectic Cr-rich alloy of carbide-based is characterized by comprising C 3.5-5.5wt.%, Cr 20-35wt.%, Mn 0.1-2wt.%, Si 0.1-1wt.%, 15wt.% or less of at least one element selected from Nb, Mo, W, Ni, a balance of Fe, and other inevitable impurities. In the alloy composition, Cr/C ratio is between 4.8 and 7.0, carbides in the matrix metal is surrounded by austenitic phase.

Description

Low stress scratch-resistant gypsum chromium carbide alloy

1 is a graph showing the behavior of low stress scratch wear according to the carbide content of the invention and the comparative material.

The present invention relates to a chromium carbide type alloy for welding for use in fields requiring abrasion resistance, such as dredging equipment, crushing holes, and more specifically, to blast-based gypsum carbide type for growth welding for improving low stress scratch abrasion resistance Relates to an alloy.

High chromium iron alloys have high wear resistance by depositing very high chromium carbides ((Cr, Fe) 7C3) with hardness values of Hv1, 100-1, and 700, when carbon and chromium elements in the alloy are bonded to each other during solidification. This is a particularly excellent alloy. These high chromium iron alloys are used throughout the industrial machine in various product forms such as cast and raised welded parts. Particularly, wear and tear areas caused by friction with soil and minerals, such as dredging equipment, crushing rolls in cement plants, raw materials of steel mills and screens of sintered ore, hoppers, raw material loading parts of thermal power plants, and inside of ready-mixed concrete machines Used for extension.

High chromium iron-based alloys with chromium carbides are very important materials in applications requiring wear resistance. These high chromium iron-based alloys are manufactured by casting or wet welding, and above all, they are inexpensive and excellent in wear resistance compared to other materials.

High chromium iron alloys are classified according to the type of matrix or chromium carbide surrounding the chromium carbide. In other words, the reporter structure surrounding chromium carbide is classified into austenite, martensite, and perlite high chromium abrasion alloys according to austenite, martensite, and perlite phase, and regardless of the matrix structure. The presence of primary carbides in carbides surrounded by matrix structures is classified into hypereutectic high chromium abrasion alloys, and those containing only primary carbides without primary carbides are categorized as hypereutectic high chromium abrasion alloys.

Austenitic high chromium iron alloys have increased chromium by 5% to the present after the first 2928C + 8% Mn + 29.5% Cr + Fe (rest) alloys were published in US Patents 1,671 and 384 in 1928. Wear resistance has been improved by increasing the amount of carbide and slightly increasing the hardness value. Martensitic high chromium iron alloys were first developed in US Pat. No. 1, 245, 552 in 1917, 2.25-2.85% C + 0.5-1.25% Mn + 0.25-1.0% Si + 24-30% Cr + Fe (rest of HC250). It has been known that the material is excellent in scratch resistance under low stress by heat treating the alloy. Since then, up to 5% of carbon and 35% of chromium are known, and the matrix is austenite or martensite, and the matrix is also used in an alloy surrounding the primary chromium carbide.

These high chromium wear resistant alloys have been used in different alloy systems depending on the conditions of use and production method. That is, in the case of castings that have been studied for many years, only two-process high chromium wear alloys are manufactured and used. This is the result of research showing that the wear resistance of the super masonry high chromium-based carbides having the best scratch resistance and the higher carbide content when the amount of carbide is around 30% decreases as the amount of carbide increases (KH Zum Gahr and DV). Doane, Mettallurgical Transactions A Volume 11A, April 1980 P613-620) and over-vacuum high chromium-based alloys cause cracks during casting. In the case of two-step high chromium abrasion alloys made from castings, alloys with austenitic matrix structures are used where the impact is severe, and martensitic matrix structures with heat treatment are used where the impact is low and higher wear resistance is required. Eggplant alloy is used.

On the other hand, in the case of over-vacuum high chromium-based alloys having coarse primary carbides and containing 30% or more of carbides, they are manufactured and used only by the growth welding method.

However, the effects of matrix structure and the amount of carbide on the scratch resistance of the grown chromium-based high chromium alloy are not known.

Accordingly, the present inventors conducted research and experiments on the effects of the matrix structure and the amount of carbides on the scratch wear resistance of the high chromium-based alloys that were grown and welded, and proposed the present invention based on the results. By appropriately controlling the component system of the chromium-based alloy, it has a coarse primary carbide and contains 30% or more of carbide, and the entire matrix structure surrounding the carbide becomes an austenite phase, thereby improving scratch resistance after fusing welding. To provide a high chromium-based carbide alloy that can be, the purpose is.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated.

The present invention is composed of weight%, C: 3.5-5.5%, Cr: 20-35%, Mn: 0.1-2%, Si: 0.1-1%, remainder: Fe and other unavoidable impurities, and the Cr / C In the chromium carbide type alloy for weld welding to improve the wear resistance of low-stress scratches where the ratio of the content is in the range of 4.8-7.0 and the matrix structure surrounding the carbides is in the range of 4.8-7.0 in the austenitic phase. It is about.

In addition, the present invention is in weight%, C: 3.5-5.5%, Cr: 20-35%, Mn: 0.1-2%, Si: 0.1-1%, Nb, Mo, W and Ni: 15 alone or in combination. %, Remaining: Fe and other unavoidable impurities, the Cr / C content ratio is in the range of 4.8-7.0 and the matrix structure surrounding the carbide is austenitic low stress scratch wear resistance chromium carbide type for improved wear resistance Relates to an alloy.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

In order to achieve the above object, in the present invention, it is preferable that the growth identification chromium carbide type alloy is formed as described above, and the reason thereof is as follows.

C is an iron strengthening element that increases the hardness of the material. In the present invention, it combines with chromium to form a hard primary chromium carbide, and the rest is solid solution in the austenite structure. Therefore, the carbon content in the present invention should be at least 3.5% that can form primary chromium carbides which contributes to the wear resistance, and when added at more than 5.5%, the brittleness of the present invention becomes poor and rather wear-resistant. Since it will inhibit, the lower limit of addition amount is preferably 3.5% and the upper limit is 5.5%.

Cr is an essential element in the present invention. Coupling with carbon and iron forms hard carbides having low cost and excellent wear resistance, and improving oxidation resistance. In order to form primary chromium carbide, 20% or more must be added, and 35% or more is not obviously improved in abrasion resistance and economical. Therefore, the lower limit of the added amount is preferably limited to 20% and the upper limit to 35%.

Mn greatly affects the process reaction depending on the addition ratio with silicon. And since it plays a role of removing dissolved oxygen in the steel for solidification, its function is weak when it is added below 0.1%, and when it is added above 2%, it lowers the hardness of the austenite phase and eventually causes the disadvantage of inhibiting abrasion resistance. Is preferably at least 0.1% and limited to 2%.

Si has a function of deoxidizing oxygen in molten steel. When 0.1% or less is added, its function is weak, and when 1% or more is added, it causes a pearlite phase which impairs brittleness and abrasion resistance of the present invention. Therefore, the lower limit of the added amount is preferably limited to 0.1% and the upper limit to 1%. .

Nb, Mo, and W combine with carbon to form carbides, and nickel imparts toughness and heat resistance. However, since these elements are expensive, the effect of addition is not clear compared to the degree of price increase depending on the amount added. Therefore, it is not necessary to add it, and since it has the effect, it is preferable that the lower limit of the addition amount is 0%, and the upper limit is limited to 15% in which the additive effect becomes insignificant compared to the degree of price increase according to the addition amount.

Among the components contained under the above conditions, the Cr / C content ratio should be maintained in the range of 4.8-7.0. The reason is that if the Cr / C is less than 4.8, the matrix structure has poor abrasion resistance. In case of more than 7.0, the Cr content is relatively high, and the effect of improving the wear resistance is insignificant compared to the price increase, but the hardness of the austenite phase, which is a matrix structure, is lowered, which adversely affects the wear resistance. Because.

After forming the growth welding chromium carbide alloy to satisfy the above conditions, it is preferable to grow and weld it on the outer surface of the base material in a conventional manner so that the matrix structure becomes an austenite phase, for the following reason. .

In the case where the matrix structure surrounding the carbide after the welding is in the form of a pearlite rather than austenite, the impact toughness is poor and high stress scratch wear resistance is degraded. And when the heat treatment after welding welding because there is a problem that less heat treatment effect.

Hereinafter, the present invention will be described in more detail with reference to Examples.

EXAMPLE

A chromium carbide alloy for growth welding was prepared to have a composition as shown in Table 1 below. This is a 9mm-thick mild steel (SS41 type) on a base metal with a working voltage of 30 volts and a current of 400 amperes, which has a bead width of 50mm and a growth layer thickness of 5mm. The type of matrix, the amount of carbide, and the amount of wear of the welded joint were measured and the results are shown in Table 2 below.

At this time, the base tissue was observed with an optical microscope, and the amount of carbide was analyzed using an image analyzer. In addition, wear measurement was performed under the same conditions of load: 20kg, wear distance: 4300m, rotational speed: 200RPM, working sand diameter: 0.15-30mm in low stress dry scratch abrasion tester (D bridge Sand Rubber Wheel Abrasive Test: ASTM Standard G65-85). It shows the amount of wear when tested at.

TABLE 1

TABLE 2

As can be seen in Table 2, in the case of the invention material (1-3) satisfying the scope of the present invention, compared to the case of the comparative material (4-7) outside the scope of the present invention, the matrix structure, the amount of carbide and It can be seen that the characteristics of equivalent to or more in the amount of wear.

In addition, the results shown in Table 2 are shown in FIG.

As can be seen from FIG. 1, in the case of (1-3) of the present invention having a chromium / carbon ratio of 4.8-7.0 based on the amount of the same carbide, the wear amount is less than or greater than 4.8-7.0. The amount of wear of the comparative material (chromium / carbon = 3-4.7 or 8-9) (4-7) was less. This means that the wear resistance of the present invention having a chromium / carbon ratio of 4.8-7.0 is superior to that of the comparative material. And in the case of the high chromium-based alloy having a chromium / carbon ratio similar to each other, the higher the amount of carbide, the lower the stress scratch resistance is improved.

As mentioned above, the alloy of the present invention is an alloy having a chromium / carbon content in the range of 4.8-7.0 and having a chromium / carbon ratio in order to produce a high-vacuum high chromium based alloy having lower stress scratch resistance than the same carbide amount. In the case of a high-vacuum high chromium-based alloy having a ratio of 4.8 / 7.0, the higher the amount of carbide, the lower the stress scratch resistance is improved. Therefore, the present invention is limited by the addition ratio of the chromium saliva carbon, which is the most important element in the eutectic high chromium-based alloy, there is an effect that can be produced a weldable welding product excellent in wear resistance.

Claims (2)

C: 3.5-5.5% by weight, Cr: 20-35%, Mn: 0.1-2%, Si: 0.1-1%, remainder: Fe and other unavoidable impurities, and the content ratio of Cr / C is 4.8 The superstructure gypsum-based carbide type alloy for growth welding for low stress scratch abrasion resistance, characterized in that the base structure surrounding the carbide in the range of -7.0 is in the austenite phase. By weight%, C: 3.5-5.5%, Cr: 20-35%, Mn: 0.1-2%, Si: 0.1-1%, single or combined Nb, Mo, W, and Ni: 15% or less, remainder: It is composed of Fe and other unavoidable impurities, the content ratio of Cr / C is in the range of 4.8-7.0, and the matrix structure surrounding the carbide is austenite phase. Carbide type alloy.