JPS58151451A - Cast iron with superior weldability - Google Patents

Abstract

PURPOSE:To inhibit the hardening of the resulting cast iron during welding and to enhance the weldability by adding specified amounts of Al and Sb to known cast iron or by further adding a specified amount of Ti. CONSTITUTION:This cast iron with superior weldability has a composition consisting of >=2.0% C, 0.1-1.5% Mn, 2.1-4.5% Si, 0.1-3% Al, 0.1-1.0% Sb and the balance Fe with inevitable impurities or further contg. 0.01-1.0% Ti.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to cast iron with excellent weldability that suppresses hardening during welding. In general, cast iron has a strong tendency to become white in the welded parts, so there are many castings that are made in one piece, even those with complex shapes, and there are few examples of welding. Minor repairs after casting,
Welding is only used to repair damage that occurs during use.
. Therefore, if weldability is improved, it is expected that the applications for wear-resistant materials, anti-vibration materials, structural materials, etc. will be dramatically expanded. Conventionally, technologies to suppress hardening caused by white pig iron have focused on improving the composition of the welding rod, the composition of the sheathing material, the welding method, and the welding equipment. It is said that in the thin solid-liquid mixed phase that exists near the interface of the melted base metal, an undiffused and incompletely diffused layer of graphitizing elements occurs, and this part solidifies into white pig iron due to the cooling effect from the base metal. From these points, there was a need for a technology to improve the weldability of the casting itself. .

The present invention adds elements that suppress hardening during welding of castings,
The purpose is to provide cast iron with excellent weldability.

That is, the present invention has (1) C: 2.0% or more, Mn: 0.1-1
．． 5%, Si: 2.1-4.5%, At: 0.1-3
%, Sb: 0.1-1.0% Casting with excellent weldability, consisting of balance iron and unavoidable impurities.

(21C: 2.0% or more, Mn: 0.1-1.5
%, Si: 2.1-4.5%, h't: o, 1-3
%, 8b: 0.1-1.0%, Ti: o, o i
Casting with excellent weldability, consisting of ~1.0% balance iron and unavoidable impurities.

It is.

In the present invention, in order to improve weldability, it is necessary to prevent the deposited metal from becoming dull. That is, the cast iron of the present invention has lower At and 8bSTi than conventionally known cast iron.
These additive elements elute into the interface between the base metal and the weld metal and into the weld metal, and become the nucleus of graphite crystallization during solidification in this area, promoting its growth and causing white pig iron formation. It is thought to prevent i. front. These elements, Yu material 1, also promote graphitization and bring about the crystallization of primary graphite, which is effective in preventing whitening. That is, during welding, this undissolved portion of primary graphite moves and diffuses to the interface between the base metal and the weld metal and to the weld metal, and in the process of solidification, this portion becomes a nucleus for graphite crystallization, promoting its growth. It is thought that this prevents whitening.

The cast iron according to the present invention will be explained in more detail below with reference to the table. Table 1 shows the test piece material melting conditions, Table 2 shows the test piece shape, Table 3 shows the chemical composition of the welding rod, and Table 4 shows the TIG welding solubility conditions.

Table 1 Test piece material melting conditions Table 2 Test piece shape Table 3 Chemical composition of welding rod (%) Table 4 TIG welding conditions Table 5 shows C: 5.69-3.82%, Mll: o,
8t with 52-0.55% as base material: 2.09-4.7
Four levels of welding base metals were melted in the 5% (7) range, and using a hypereutectic welding rod, the T
Id welding was performed, and the characteristics of the welded part were examined to evaluate weldability.

Table 5 shows the chemical composition of the weld base metal containing 8i and the chemical composition of the weld base metal, the characteristics of the weld zone, and the overall evaluation. No whitening was observed at the interface, fracture occurred from the base metal in the tensile test, and the hardness was below Hv 300, which is easy to machine. However, the base material containing 4.85% Si, the cast iron in the present invention HRB = 10, which is the hardness allowed for
It's over 0.

Table 6 shows C: 3.64-6.78%, 8i: 2
．． 57-2.62%, Mn: 0.49-0.52%
Welded surface materials of four levels in the range of At: 0.9 to 4.2% were made using the base material under the same conditions as in Table 1, and welded under the same conditions as in Section 2.3.4. Table 6 shows the chemical composition of the At-containing weld base metal, the properties of the weld zone, and the overall evaluation. It is something that At1.0-4.0%
No whitening was observed at the interface between the base metal and the welded metal within the range of , and fracture occurred at the base metal in the tensile test. Quiche graphite crystallization, which inhibits melting workability, was 1.0 to 4.0%, which was so small as to pose no problem, and was not observed at less than 1.0%. The hardness was 180% or more, Hv = 300 or less, and machining was extremely easy. Therefore, an appropriate At content is 1.0 to 4.0%.

Table 7 shows C: 5.64-3.74%, Si: 2.60
~2, <53%, Mn: 0.48 to 0.52 Using X as a base material, four levels of welding materials in the range of sb: 0.04 to 1.15% were melted under the same conditions as in Table 1. Welding was performed under the same conditions as in Table 2.3.4, the characteristics of the welded part were investigated, and the weldability was evaluated.

Table 7: Chemical composition, weld zone properties, and comprehensive evaluation of sb gold-containing weld base metal Table 7 shows the chemical composition, weld zone characteristics, and comprehensive evaluation of sb gold-containing bath base metal. 8b: At 0.05% or more, whitening does not occur at the interface between the base metal and the weld metal. At 1.01%, crystallization of irregular graphite was observed. In the tensile test, samples containing Sb in the range of 0.05 to 1.01% broke at the base material. In the same range, the roughness was less than Hv = 500, and machining was possible but rare.

Therefore, sb gold-containing lri of 0.05 to 1.00% is appropriate.

As shown in the actual examples above, the elements Si, At, and Sb were added to suppress the hardening of the welded shaft of cast iron, and their suppressive effects were investigated and found to be effective.

The content of these elements is 8i: 2.1-4.5%, At
: 0.1-5.0%, Sb: 0.1-1.0%, 5
If the i(7) content is less than 2.1%, whitening at the interface between the base metal and the weld metal cannot be prevented. 4.5
%, the solid solution of 8i in the ferrite crystals increases, causing hardening and ductility inhibition. When At is contained, whitening cannot be prevented if the amount is less than 0.1X.

4% more than 3%, due to excessive crystallization of primary graphite in the base material,
This results in a decrease in strength, and during welding, quiche graphite crystallizes, impeding welding workability and worsening the appearance of the welded part. sb
If gold is contained, if it is less than 0.1%, white: stain cannot be prevented. If it is more than 1.0%, the graphite shape will change and the strength and ductility of the base metal and welded part will be impaired. In this way, the present invention provides Si in ordinary cast iron.
By coexisting At, At, and Sb, cast iron with extremely high weldability can be obtained. °5 By the way, pearlite precipitates in the base of the weld base metal containing sb, which may impede the ductility of the base metal. HTi is added to prevent this. .

Table 8 C: 5.56-6.61%, Si: 2.5
7-2.65%, Mn: 0.49-0.54%, 8
b: 0.95-1.03% Ti: 0.00 as base material
8-1. Four levels of welding materials in the range of [l 2 [1%] were melted under the conditions shown in Table 1, and the state of precipitation of pearlite and the state of crystallization of Ti inclusions were investigated.

Table 8 Chemical composition of weld base metal containing 8b + Ti Precipitation status of pearlite, crystallization status of Ti inclusions As shown in Table 8,
Above 10% TiO, pearlite disappears and Ti
Crystallization of Ti inclusions was observed at 1.020% or more. Therefore, in the weld base metal containing Sb O,05~i,o,o%, l"I Ti O,010~i,o o
In addition to Ti, Ni, Co, and C can be used as elements to prevent pearlite precipitation, which is suitable for containing 0% gold.
There are elements such as u and B, and it is also possible to utilize these elements.

Example 1 Cast iron consisting of the elements with the chemical components shown in Table 9, the balance iron, and unavoidable impurities was melted under the conditions shown in Table 1, and elmed into the shapes shown in Table 2. TIG welding was performed under the conditions shown in Table 4 using a welding rod having the same composition, and various characteristics of the welded parts were investigated. As a result, no crystallization of white pig iron was observed, and in the tensile test, the hardness at which the base metal broke was less than 600 Vickers hardness, and it could be easily machined. Further, crystallization of quiche graphite was not observed. As mentioned above, this base material has excellent weldability. Incidentally, some pearlite precipitation was observed at the base of the metallographic structure of the base material.

Example 2 A cast iron welding base material consisting of the elements having the chemical composition shown in Table 10, the balance iron, and unavoidable impurities was melted under the conditions shown in Table 1 &), and processed into the shape shown in Table 2. Using a welding rod having the chemical composition shown in Table 3, TIG welding was performed under the conditions shown in Table 4, and as in Example 1, various characteristics of the welded part were investigated.

As a result, pearlite and Ti are added to the base metallographic structure of the base metal.
No crystallization of inclusions was observed. In addition, no crystallization of white pig iron or black lead graphite occurred in the welded part, and the hardness was less than 300 Vickers hardness. As mentioned above, this welding base material has excellent weldability at the welded part and the properties of the base material itself.

Claims (1)

[Claims] (11C: 2.0% or more, Mn: 0.1 to 1.5%
, Si: 2.1-4.5%, At: 0.1-6%, S
b: Cast iron with excellent weldability characterized by being comprised of 0.1 to 1.0%, the balance being iron and unavoidable impurities. (2) C: 2.0% or more, Mn: 0.1~
1.5%, Si: 2.1~4.5%, At: 0.1~
3%, Sb: 0.1-1.0%, Ti: 0.0
A cast iron with excellent weldability characterized by comprising 1 to 1.0%, the balance being iron and unavoidable impurities.