JPH08141782A - Welding material for hard facing onto cast iron base metal - Google Patents

Abstract

PURPOSE: To reduce the cladding by welding work by reducing the carbon content eluted from the base metal into the clad part in the case of cladding the welding material onto the cast iron base metal made from the welding material thereby enabling the single layer welding. CONSTITUTION: When the welding material is cladded by welding onto the case iron base metal and hardened by the super cooling, the carbon in the cladded part is eluted from the cast iron base metal, and the carbon content in the cladded part is increased by 0.4-0.9%. Thus, the carbon content in the composition (Point X) of the cladded part of the welding material is preliminarily reduced by 0.4--0.9%, and the welding material in the range Y is deposited. Even when the carbon is eluted into the cladded part by the cladding by welding, the carbon content in the cladded part becomes the preset value, multi-layer welding is unnecessary, and the single layer welding is sufficient, and the process for necessitating the work is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a welding material used for hardfacing on a cast iron base material, and more specifically,
It is used in fields where the shape of cold press dies such as press dies for pressing metal thin plate materials such as aluminum and steel plates is complicated and machinability and hardness after welding are required. Related to welding materials.

[0002]

2. Description of the Related Art For example, a trimming die for cutting a blank material of a certain length from a metal thin plate roll material such as aluminum or a steel sheet, or a blank die after drawing the blank material with a draw die, there is no need for a peripheral portion. When manufacturing a trimming die for cutting off a part, the welding material as a blade material is welded to the die material cast in a predetermined shape, the blade is cut out from this welded portion, and then the blade is cut. The hardness of is increasing.

Since such a welding material for overlay welding is machined into a predetermined shape, it is preferable that the hardness after overlaying is low, and the hardness becomes relatively high after forming by machining. Desirably, for example, JP-A-6-154
According to Japanese Patent No. 81, the hardness of the weld metal after the martensite transformation start temperature (hereinafter referred to as Ms temperature) is set to 150 ° C. or less and the weld overlay is HRC 45 or less,
Further, there is known a welding material in which the hardness is HRC45 or more by performing a supercooling treatment at 0 ° C. or less after welding.

[0004]

The above-mentioned conventional welding material contains 0.50 to 1.50% of carbon, and when it is plastically processed into a wire shape, it is work hardened and easily broken. Therefore, the above-mentioned conventional welding material can only be formed into a rod shape, but it is necessary to form it into a wire shape in order to automate the build-up process by a robot or the like.

Further, when the base material for the weld overlay is made of cast iron, carbon is leached from the cast iron base material side into the weld metal, and the hardness becomes high, which causes a problem that machining becomes difficult. In order to prevent such an adverse effect, as shown in FIG. 3, a welding material is multi-layered on the base metal 1, for example, two layers of three beads are built up, and the beads 2a and 2b of the inner layer are formed in the cast iron base metal. Although it is necessary to make the specific composition of the weld metal in the bead 2c of the outer layer part that is built up with the same welding material even if the above-mentioned carbon is involved, if the multi-layered work is performed in this way, it is often used for the work of building up. It takes man-hours.

Therefore, an object of the present invention is to provide a welding material which does not break even if it is formed into a wire shape and requires a small number of man-hours for overlaying work.

[0007]

In order to achieve the above-mentioned object, the present invention is a welding material which is welded to a cast iron base material and then hardened by supercooling treatment. It is characterized in that the carbon content is reduced by 0.4 to 0.9% with respect to the carbon content in the composition of the deposited metal determined from the hardness after the treatment.

[0008]

[Function] When the weld overlay is formed on the cast iron base material, carbon is eluted from the cast iron base material into the overlay portion and the amount of carbon in the overlay portion is 0.4 to
0.9% increase. Therefore, if the amount of carbon in the component composition of the welding material is previously reduced by 0.4 to 0.9% as in the above-described present invention, the amount of carbon in the buildup portion due to the elution of carbon by the weld buildup. The ratio has been set, and it is not necessary to lay it in multiple layers, and a single layer suffices.

When the carbon content of the welding material is reduced in this way, even if the welding material is plastically processed into a wire shape, it does not work harden and does not break.

[0010]

EXAMPLE According to the above-mentioned JP-A-6-15481,
The hardness after weld overlay is lower than HRC45, and the hardness after supercooling treatment is higher than HRC45.
The difference from 45 is large, and the Ms temperature is 50 to 60.
It is about ℃.

Here, the Ms temperature is calculated by the following equation, and M
The ratio of each component was determined so that the s temperature was 50 to 60 ° C. An example of the component composition is shown below.

Ms (° C.) = 538 −317 × C−33 × Mn−17
XNi-28xCr-11xMo-11Si-11xW Component composition (% by weight) C Mn Ni Cr Mo Si W 1.1 1.0 0.5 0.5 3.0 0 1.0 0 The structure of the welding material according to the composition is verified using FIG. FIG. 1 is a Schaeffler's organization chart, showing the organization with the Ni equivalent shown on the vertical axis and the Cr equivalent shown on the horizontal axis. Substituting the above component compositions into the following equations for obtaining the Ni equivalent and the Cr equivalent respectively Find the value of.

Ni equivalent = 30 × C + 0.5 × Mn + Ni = 34 Cr equivalent = Cr + Mo + 1.5 Si = 4.5 This calculation result corresponds to point X in FIG. 1, residual austenite exists, and supercooling occurs. It is expected that the treatment can transform into martensite and increase hardness. However, since retained austenite transforms into martensite due to external stress as well, when the welding material having this component composition is plastically processed into a wire shape, the retained austenite transforms and the welding material is easily broken.

From this component composition, carbon is 0.4 to 0.9%.
When the amount is decreased, the Ni equivalent is decreased by 12 to 27,
become. When this is represented in the Schaeffler organization chart of FIG. 1, Y
It is understood that the range is as shown in, and almost no austenite remains. Therefore, even if the welding material having a reduced carbon content is processed into a wire shape, it is not work-hardened and there is no fear of breaking the wire-shaped welding material.

With reference to FIG. 2, reference numeral 1 denotes a trimming type base material formed of cast iron, which has a chamfered edge portion which serves as a blade portion of the trimming type, and the chamfered portion has the above-mentioned wire-shaped welding material. Is welded to a single layer by MIG welding. In this case, carbon is eluted from the base material 1 into the built-up portion 2, and the composition of the built-up portion 2 approaches point X in FIG. Therefore, a large amount of austenite remains in the structure of the build-up portion 2, the hardness after the weld build-up is low and it is easy to machine, and after that, it is possible to transform the austenite into martensite by the supercooling treatment to increase the hardness. it can. When the welding material is multi-layered unlike conventional welding materials, the amount of carbon is insufficient and the hardness cannot be increased. On the other hand, when the single-layer welding is applied, the hardness originally intended can be obtained. Therefore, since it is not necessary to stack multiple layers, the man-hours required for the weld overlaying work are smaller than those of the conventional one.

Although the welding material according to the present invention can be processed into a wire shape, it may be processed into a rod shape to perform weld overlaying, or may be powdered into an overlay by plasma spraying or the like.

[0017]

As is clear from the above results, when the welding material according to the present invention is used to perform weld overlaying on a cast iron base material, it is necessary to perform multi-layer deposition as in conventional welding materials. Instead, a single-layer build-up is sufficient, and the number of man-hours required for welding build-up work is reduced. Further, since the welding material of the present invention does not break even if it is processed into a wire shape, it is possible to easily automate the welding build-up work.

[Brief description of drawings]

[Fig.1] Organization chart of Schaeffler

FIG. 2 is a cross-sectional view of a buildup portion using the welding material according to the present invention.

FIG. 3 is a cross-sectional view of a built-up portion with multiple layers.

Claims (2)

[Claims] 1. A welding material, which is welded to a cast iron base material and then hardened by supercooling treatment, wherein the amount of carbon in the component composition of the weld metal is determined from the hardness after welding and the hardness after supercooling treatment. A welding material for hardfacing to a cast iron base material, characterized in that the carbon content is reduced by 0.4 to 0.9%. 2. The welding material for hardfacing to a cast iron base material according to claim 1, which is formed into a wire shape.