KR100647970B1 - Steel for cutting tool - Google Patents

Abstract

A steel composition comprises (wt.%): 0.88-1.12 carbon; 3.4-4.5 chromium; 2.5-3.0 molybdenum; 0.7-1.0 vanadium; 0.04-0.1 aluminum; 0.02-0.12 nitrogen; and balance manganese, silicon, iron and residual impurities.

Description

Steel for Cutting Tools {STEEL FOR CUTTING TOOL}

The present invention relates to steel for cutting tools.

When the chip is removed from the workpiece, the cutting area of the tool is substantially subjected to high loads due to heat, friction, toughness and compression, in which case the stresses of the tool and the material act simultaneously. Individual alloy compositions are well known in the art that take into account the most important requirements present in the profile to achieve the maximum life of the tool when different load profiles are provided.

High wear resistance of the tool can generally be achieved by using high-speed steel, which contains a large amount of expensive molybdenum and / or tungsten with a concentration of up to 20% by weight as alloying element. This alloy element also includes vanadium, and in the case of conventional high speed steel or PM-high speed steel, vanadium is added in an amount of 1.2% by weight to 10.0% by weight.

As mentioned above, high speed steels can be selected to suit the stress profile of the tool in terms of their composition, but have the disadvantage of incurring expensive alloy and material costs. In consideration of cost, if the concentration of the main alloy element is lowered, the heat treatment characteristics, hardness and general use characteristics of the steel (steel) may be drastically deteriorated.

It is an object of the present invention to provide a steel which eliminates the disadvantages of the prior art, is very suitable for cutting tools by alloy processing and achieves high economic efficiency.

The purpose is

C = 0.88 to 1.12

Cr = 3.4 to 4.5

Mo = 2.5 to 3.0

V = 0.7 to 1.0

Al = 0.04 to 0.1

N = 0.02 to 0.12 and

Achieved by the steel for cutting tools containing Fe and the unavoidable element (% by weight) as the remainder.

The advantages achieved by the present invention are that of heat-treated steel by the combination of molybdenum and vanadium, which are provided in much lower concentrations on the one hand than high speed steel, and on the other hand, aluminum and nitrogen, which are provided in a relatively higher content than in the prior art. When the toughness and the compressive force have a sufficient size, desirable high temperature durability and especially high wear resistance can be achieved. Cutting tools made of alloys according to the present invention contain less expensive alloying elements and therefore can be manufactured at low cost, but also have high stability against very important requirements in load profiles.

It has been found that the cutting process is more appropriate in the cutting surface or in the area behind the cutting edge of a tool made of steel according to the present invention, with relatively small depressions. The reason for this cannot be explained scientifically, but may be assumed to be the synergy effect of aluminum, nitrogen, carbon and vanadium. The high affinity of elements such as vanadium for carbon and nitrogen not only provides high temperature durability, preferably with the formation of very fine and uniformly distributed carbides and carbonitrides upon heat treatment, It is possible to contain a sufficient amount of reactive aluminum in the matrix, which is oxidized when temperature loads appear in the cutting zone of the tool to form an alumina surface layer, such as a coating that facilitates the cutting process. Aluminum in the matrix has also been demonstrated to promote high temperature durability and tempering stability of the material according to the invention.

Vanadium in the alloy can be partially replaced with up to 0.45% by weight of niobium, but in this case the carbon content can be given below the concentration limit.

According to one preferred embodiment according to the invention

C = 0.93 to 1.07

Si = 0.15 to 0.42

Mn = 0.15 to 0.44

P = 0.03 max

S = 0.001 to 0.3

Al = 0.05 to 0.07

N = 0.03 to 0.1

Steels containing at least one of the elements (% by weight) of can be used for cutting tools.

By mixing alloying elements within a given concentration range, areas of particular importance in the property profile of the tool can be further increased.

When the ratio of aluminum to nitrogen is 0.5 to 1.9 (Al / N = 0.5 to 1.9), the material according to the invention has high high temperature durability and toughness in the heat treated state or after curing at 450 ° C to 500 ° C and at least one tempering. In this state the cutting wear of the tool has a minimum value.

Circular saws with high economy and high lifespan in heavy equipment and having a hardness of at least 63 HRC, preferably at least 64 HRC, can be produced by the steel according to the invention.

Looking in detail at an embodiment of the invention showing only the composition of the steel as compared to the commonly used material DIN No.1.3343:

A heat treated toothed circular saw blade with a diameter of 400 mm was fixed on the common axis, so that the tough metal bar was separated into pieces in the separator.

According to the invention Vers. Between saw blades made of an alloy designated as A1 type in Table 1, which proved to be suitable in relation to the life of the saw blade. Saw blades made of the alloy marked L.3 were inserted.

A comparative evaluation of the results until the saw blade axis is separated due to wear is presented in Table 2, where the value of the Al type is presented as 100%. These results show that the cutting performance of cutting tools, especially circular saw blades, can be high when using the material according to the invention.

material Chemical composition C Si Mn P S Cr Mo V W Al N A1 type 0.91 0.32 0.4 0.011 0.012 4.13 5.21 1.81 6.44 - - Vers.L.3 0.96 0.27 0.24 0.01 0.009 4.01 2.78 0.88 - 0.082 0.086

Table 1

material usage time(%) Hardness (HRC) Cutting wear (%) Cutout (%) Cutting breakage (%) A1 type 0 65 - - - Vers.L.3 0 64 - - - A1 type 30 - 100 100 100 Vers.L.3 30 - 103 95 100 A1 type 60 - 100 100 100 Vers.L.3 60 - 107 89 200 A1 type 90 - 100 100 100 Vers.L.3 90 - 106 86 100

TABLE 2

The present invention eliminates the shortcomings of the prior art and provides a steel which is very suitable for cutting tools by alloy processing and achieves high economic efficiency.

Claims (5)

C = 0.88 to 1.12 Cr = 3.4 to 4.5 Mo = 2.5 to 3.0 V = 0.7 to 1.0 Al = 0.04 to 0.1 N = 0.02 to 0.12 and Containing Fe and the unavoidable element (% by weight) as the remainder, Cutting tool steel. The method of claim 1, C = 0.93 to 1.07 Si = 0.15 to 0.42 Mn = 0.15 to 0.44 P = 0.03 max S = 0.001 to 0.3 Al = 0.05 to 0.07 N = 0.03 to 0.1 Containing at least one of the elements (% by weight) of Cutting tool steel. The method according to claim 1 or 2, The ratio of aluminum to nitrogen is 0.5 to 1.9 (Al / N = 0.5 to 1.9), Cutting tool steel. Made of the steel according to claim 1 or 2 and having a toothed edge region of hardness of at least 63 HRC, Circular saw blade. Made of the steel according to claim 3 and having a toothed edge region of hardness of at least 63 HRC, Circular saw blade.