JPH0459943A - Shank material for high speed steel tool - Google Patents

Abstract

PURPOSE:To manufacture a shank material for a high speed tool excellent in weldability or the like by preparing a steel having a specified compsn. in which each content of Si, Mo and Cr is prescribed. CONSTITUTION:A steel contg., by weight, 0.40 to 0.80% C, 0.40 to 1.50% Si, 0.20 to 2.00% Mn, 0.50 to 3.00% Cr, 1.00 to 3.00% Mo and <=0.30% V, furthermore contg., at need, 0.02 to 0.30% Nb and the balance Fe with inevitable impurities is prepd. In this way, the shank material excellent in weldability with a high speed steel, high in strength in the weld zone and furthermore having sufficient hardness even if heat treatment is executed simultaneously with the high speed steel can be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a shank material for end mills, drills, etc. whose blade material is made of high-speed steel and whose shank is welded by various welding methods.

[Conventional technology]

In cutting tools such as end mills that are manufactured using high-speed steel, conventionally, in order to save on expensive high-speed steel, the shank is made from low-grade steel such as carbon steel, and then friction welded or flash butt welded. Joined by etc.
Costs are being reduced by manufacturing so-called composite tools.

However, when these materials are jointed with high-speed steel and subjected to simultaneous heat treatment, the grains become coarser.
Since toughness decreases, it is generally necessary to perform a two-stage heat treatment in which only the high-speed steel is first placed in a salt bath, and after a predetermined period of time, the shank portion is immersed.

In addition, in recent years, there has been remarkable development of high-speed steel for cutting difficult-to-cut materials.
It has come to be used in many cutting tools such as end mills, but conventional shank materials have low weld strength, and when heat treated simultaneously with high-speed steel to improve heat treatment workability, it is difficult to achieve sufficient hardness. This results in a lack of strength, which causes accidents such as buckling, making it unusable, and at the same time, the color of the shank material is different from that of the high-speed steel, making it inferior in commercial value.

[Problem to be solved by the invention]

The present invention is inexpensive, has excellent weldability, has high weld strength, and has high hardness of HRC50 or higher even when heat-treated simultaneously with high-speed steel.The color of the shank material is the same as that of high-speed steel, so it has commercial value. The purpose is to obtain a shank material for high-speed steel tools with high viscosity.

(Means for solving the problem) As a result of intensive research to solve the above problem, the inventors have discovered that
The present invention was completed by discovering that steel having the composition shown below is suitable.

That is, in the present invention, the weight ratio of C is 0.40 to 0°80%.
, Si; 0.40-1.50%, Mn; Q.

20-2.00%, Cr; 0.50-3.00%M
o: 1.00-3.00%, V: 0.30% or less, and further contains Nb, 0.02-0.30 as necessary.
This is a shank material for high-speed steel tools characterized by containing %.

The present invention is characterized in that a hardness of HRC50 or higher can be obtained even when heat-treated simultaneously with high-speed steel, by combining the effect of Si and Mo and increasing the softening resistance by incorporating Cr.

In addition, by suppressing the Cr content to 3.00% or less, weld cracking between high-speed steel and shank material can be prevented, and the difference in color between high-speed steel and shank material can be eliminated even when heat treatment is performed simultaneously. In addition, the transverse rupture strength of the welded part is 320
kgf/mm" or more.

Therefore, it has higher strength and weld strength than conventionally used shank materials, and has good heat treatment workability, and can greatly contribute to improving the performance of high-speed steel tools for cutting difficult-to-cut materials. be.

The reasons for limiting the ingredients of the present invention will be described below.

c; 0-0.80% C is an essential element that solidly dissolves in the matrix and strengthens the material, forming carbides with Cr, Mo, etc. to improve wear resistance.
Furthermore, in order to achieve a hardness of HRC50 or higher even when heat-treated simultaneously with high-speed steel, It is necessary to contain 40% or more, but if it is contained in excess of 0.80%, the toughness will drop significantly, so the range of the components was set to 0.40 to 0.80%.

Si: 0.40-1.50% Si is an element necessary for deoxidation and is effective for strengthening the base, and for that purpose it is necessary to contain 0.40% or more, but 1.50% If the content exceeds 0.00, the toughness will drop significantly and decarburization will be accelerated, so the range of the components should be reduced to 0.
The content was set at 40 to 1.50%.

Mn; 0.20-2.00% Mn is an element necessary for deoxidation like Si, and
It is effective in improving hardenability, and for that purpose it must be contained at 0.20% or more, but if it is contained in excess of 2.00%, annealing hardness will increase and workability will decrease, so the component The range was 0°20 to 2°00%.

Cr: 0.5 (1 to 3.00% Cr improves temper softening resistance and forms carbides to increase wear resistance. It is also an effective element for improving hardenability, and therefore requires a content of 0.50% or more,
If the content exceeds 3.00%, weldability deteriorates, so the range of the content was set to 0.50 to 3.00%.

Mo; 1. OO~3. OO%Mo is an element that increases resistance to temper softening, and for that purpose 1.00%
However, if the content exceeds 3.00%, the toughness will decrease, so the content range should be adjusted to 1.00 to 3.
．． It was set as 00%.

V: 0.30% or less V is an element that contributes to improving strength and temper softening resistance, but it is expensive, so it was set to 0.30% or less.

Nb; 0.02 to 0.30% Nb has the effect of preventing coarsening of crystal grains and increasing toughness, and for this purpose it is necessary to contain 0.02% or more, but if the content exceeds 0.30% Even if it is contained, the effect is saturated, so the component range is set to 0.02 to 0.30%.

〔Example〕

Next, the features of the present invention will be explained using examples.

The chemical components of the present invention are shown in Table 1.

In Table 1, A-K steel is the steel of the present invention, and A-C steel is the first steel.
The invention steel, DSE steel, is the second invention steel.

JIS F-J steel is comparative steel and K steel is conventional steel.

It is 555C.

The hardness, weldability, color of the weld shank material, and weld transverse rupture strength of these steels after heat treatment were investigated.

Hardness is 1190 in vacuum, same as heat treatment of high speed steel.
After being kept at 15 minutes at
After holding at 0″C for 2 hours and repeating air cooling tempering three times,
The hardness was measured using a Rockwell hardness needle.

Weldability was determined by friction welding a material with a diameter of 16 mm with high-speed steel of the same diameter, and after processing it into an end mill, we observed whether there were any defects such as cracks in the welded part.

Next, the end mill whose weldability was investigated was heat treated under the same conditions as for hardness measurement, and after visually observing the color of the high-speed steel and shank material, it was subjected to a 4-point bending bending test to measure the transverse rupture strength of the weld. did.

These results are shown in Table 2.

(Margin below) Table 2 In Table 2, regarding color, there is no difference in color between high-speed steel and shank material at all, marked with ○, and with a slight difference in color, marked with Δ. Those that are clearly recognized are marked with an X.

Comparative Steel F has low hardness and transverse rupture strength due to its low C content, while Comparative Steel G with high Cr content and Comparative Steel H with high C content have defects in welds, poor color, and poor transverse rupture strength. Power is also low. Comparison 8j, which has a high MoC content, has poor color and transverse rupture strength, and conventional wAK has low hardness and transverse rupture strength. On the other hand, it is clear that the steel of the present invention is superior in terms of hardness, weldability, color, and transverse rupture strength of the weld zone compared to comparative steels and conventional steels.

〔Effect of the invention〕

As explained above, the present invention has discovered a material suitable as a shank material for high-speed steel tools, and its characteristics include excellent weldability with high-speed steel, high weld strength, It is a material that has many advantages, such as being sufficiently hard and having a good color even when heat-treated simultaneously with high-speed steel, and being relatively inexpensive despite its low commercial value. This will greatly contribute to improving the performance of high-speed tools.

Claims (2)

[Claims] (1) Weight ratio: C: 0.40-0.80%, Si
;0.40-1.50%, Mn;0.20-2.00%
, Cr: 0.50-3.00%, Mo; 1.00-3.
A shank material for a high-speed steel tool, characterized in that it contains 0.00%, V: 0.30% or less, and the remainder consists of Fe and inevitable impurities. (2) C: 0.40-0.80%, Si by weight ratio
:0.40~1.50%, Mn:0.20~2.00%
, Cr: 0.50-3.00%, Mo: 1.00-3.
00%, V; 0.30% or less, Nb; 0.02 to 0.3
A shank material for a high-speed steel tool, characterized in that it contains 0% Fe and the remainder consists of Fe and unavoidable impurities.