JPH03294084A - Welding wire for high-hardness build-up welding - Google Patents

Abstract

PURPOSE:To allow good build-up welding having high wear resistance, excellent toughness and good corrosion resistance by specifying the compsn. of the welding wire for high hardness building up. CONSTITUTION:The welding wire for high hardness build-up welding is produced of an alloy having the compsn. which contains 0.40 to 0.55% C, 0.9 to 3.0% Si, <=0.6% Mn, and 7.5 to 9.5% Cr, contains <=0.03% P and <=0.03% S and consists of the balance substantially Fe. The build-up metal having high hardness of >=600 hardness Hv is obtd. in this way.

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a welding wire for gas-shielded arc welding that provides a highly hard overlay metal with a hardness of Hv 600 or more. 4. Prior Art Mechanical parts used under harsh conditions, such as the tip of a construction machine such as a power shovel, must have both high wear resistance and toughness. Conventionally, such parts have been manufactured by using strong steel for the main body and overlaying and welding high-hardness metal on the parts that come into contact with earth and sand to increase wear resistance. As an example of build-up welding material for this purpose, rDs45
0J (Daido Steel's solid wire for gas shielded arc welding) has a typical alloy composition of 0.
．． 24C-0,87Si-2.12Mn-2,23O
r-0,84Mo-0,36V-Fe, CO2
The hardness of weld metal built up by gas-shielded arc welding is limited to Hv450-550. Although there is an endless demand for improving the wear resistance of build-up weld metal, there is currently no welding wire for build-up that provides a weld metal with a hardness of MV 600jX or higher and exhibiting high wear resistance. [Problems to be Solved by the Invention] The purpose of the present invention is to improve the current state of the technology as described above, and to provide a metal overlay that has a hardness of HV 600 or more, has excellent wear resistance, and has good toughness. It is an object of the present invention to provide a high-hardness overlay welding wire that is high in temperature, generates little spatter during welding, and has a low risk of weld cracking.

[Means to solve the problem]

The high hardness overlay welding wire of the present invention basically has C:
0.40-0.55%, Si: 0.9-3.0%,
Mn: 0.6% or less and Cr near. Contains 5 to 9.5%, P: 0.03% or less, S20.
0.3% or less, and the remainder is made of an alloy having a composition consisting essentially of Fe. In addition to the above-mentioned basic composition, this alloy can contain one or more components belonging to the following additive element groups. b) B: 0.001 to 2.5%, and V: 0. O
One or two types of O1-2.5%) Mo: 0.1-8.5%, Ni: 0.1-2.
5% and W: 0.1 to 10.0%, one or more types [Function] In the present invention, the reason why the composition of the alloy used as the material of the welding wire is determined as above is as follows. It is. C: 0.40-0.55% In order to obtain high hardness and wear resistance, a certain amount of C is required.
Requires. On the other hand, a large amount of C causes cracks. It is within the narrow range mentioned above that the two can be reconciled. Si: 0.9 to 3.0% In order to stabilize welding and reduce the amount of spatter, the presence of 81 of at least 0.9% is required, and addition of 2% or more is preferable. However, if the amount is too high, pores tend to form on the surface of the weld metal, so addition of more than 3% must be avoided. Mn: 0.60% or less Mn is added as a deoxidizing agent, but since it lowers the cold workability when drawing the alloy material into welding wire, the addition is limited to 0.6% or less. Cr: 7.5-9.5% In order to increase hardness and improve wear resistance, Cr must be present along with an appropriate amount of C. However, like C, a large amount of Cr causes weld cracking and reduces toughness and ductility, so the above range was determined as an appropriate addition amount for Qr. Both P: 0.03% or less and S: 0.03% or less are undesirable impurities that cause weld cracking and reduce toughness and ductility, and the material must be refined to be within the above-mentioned allowable limits. B: 0.001 to 2.5% ■ = 0.001 to 2.5% These elements make the structure finer and increase toughness, and also contribute to improving hardness by forming carbides. These effects can be seen with a small amount of addition of about 0.001%, but even if added in a large amount, it becomes saturated and may even cause cracking or reduce toughness and ductility.
The upper limit was set at 5%. Mo: 0.1-2.5%, Ni: 0.1-2.5
%, w: o, "t ~ 10.0% These give corrosion resistance to overlay metal and improve wear resistance. Both are effective when added at 0.1% or more, but the effect becomes less effective when added in large amounts. Since it will saturate, it is best to choose an amount within each upper limit.

【Example】

An alloy having the composition shown in the table was melted, and the fracture energy value Ky f was obtained when a test piece with a U notch was subjected to a Charpy tester at 0°C.
m) was measured. Each alloy was processed into a solid wire with a diameter of 1.2J* or 1.6J by hot rolling followed by wire drawing. Using this, overlay welding was performed under the following conditions. Welding method: MAG Shielding gas: 20% CO2 + Ar The presence or absence of cracks in the welded metal part was inspected by penetrant testing, and the amount of spatter was also examined. Subsequently, an abrasive wear test was conducted to measure the amount of wear per 0.5 hours. The product of the hardness HV and toughness LJEO was calculated and determined as the "K value", which was used as a measure of the performance of the overlay alloy. The above results are also shown in the table.

【Effect of the invention】

By using the welding wire of the present invention, the hardness is Hv
600 or higher, and has high wear resistance, excellent toughness, and good corrosion resistance, overlay welding can be realized with a reduced amount of spatter and a low risk of weld cracking. Overlay welding using this wire reduces the burden of maintenance when applied to parts that require both wear resistance and toughness, such as parts of construction machinery mentioned in the beginning. The welding wire of the present invention can be used not only for MAG welding as shown in the embodiments, but also for TIG welding and submerged welding.

Claims (4)

[Claims] (1) C: 0.40-0.55%, Si: 0.9-3.
0%, Mn: 0.6% or less and Cr: 7.5 to 9.5
%, P: 0.03% or less, S: 0.03% or less, and the balance is substantially Fe. (2) In addition to the components described in item 1, B: 0.001 to
A welding wire for high hardness overlay manufactured from an alloy having a composition containing 2.5% and one or both of V: 0.001 to 2.5%. (3) In addition to the components described in item 1, Mo: 0.1 to 8
．． 5%, Ni: 0.1-2.5% and W: 0.1-1
A welding wire for high hardness overlay manufactured from an alloy with a composition containing 0.0% of one or more types. (4) In addition to the components described in item 1, B: 0.001 to
2.5% and one or two of V: 0.001-2.5%, Mo: 0.1-8.5%, Ni: 0.1-2.
5% and W: 0.1 to 10.0%.