The additive that crystallizes graphite into a ball in cast iron is called "spheroidizing agent".The main components of         "spheroidizing agent" are spheroidizing elements, such as Mg, Ce, Ca, etc.The spheroidal graphite in nodular cast iron is formed by spheroidization of iron solution of cast iron, which makes its strength much higher than that of gray cast iron, its toughness better than that of malleable cast iron, and it can maintain a series of advantages of gray cast iron.However, the "spheroidizing agent" used in the melting of nodular cast iron can increase the tendency of producing "white mouth" and hardening tissues in the weld, and cause cracks in the weld and the heat-affected area (especially the fusion area).So the weldability of nodular cast iron is worse than that of gray cast iron.

        It includes magnesium silicon series alloy, rare earth magnesium silicon series alloy, calcium series alloy (more used in Japan), nickel magnesium series alloy, pure magnesium alloy, rare earth alloy.Among them, rare earth magnesium ferrosilicon alloy is the most widely used. Calcium-magnesium spheroidizing agent is mainly produced and applied in Japan. For example, the magnesium content of calcium-magnesium alloy NC5, NCl0, NCl5, NC20 and NC25 produced by SHIN -- ETSU of Japan varies from 4% to 28% (mass fraction), but the calcium content varies little, ranging from 20% to 31% (mass fraction).This kind of alloy has a small tendency of white mouth, but requires high treatment temperature and large amount of slag after treatment.Nickel-magnesium alloy has been used in America and Europe. The advantages of these alloys are relatively high density, stable reaction, nickel can play an alloying role, and the price is high. This kind of alloy is seldom used in China.The pure magnesium alloy should be treated with special pressure and magnesium package. The magnesium absorption rate is high, but the treatment safety measures are very strict.

Rare earth is the spheroidizing agent used in the invention of nodular cast iron.

It includes magnesium silicon series alloy, rare earth magnesium silicon series alloy, calcium series alloy (more used in Japan), nickel magnesium series alloy, pure magnesium alloy, rare earth alloy.Among them, rare earth magnesium ferrosilicon alloy is the most widely used. Calcium-magnesium spheroidizing agent is mainly produced and applied in Japan. For example, the magnesium content of calcium-magnesium alloy NC5, NCl0, NCl5, NC20 and NC25 produced by SHIN -- ETSU of Japan varies from 4% to 28% (mass fraction), but the calcium content varies little, ranging from 20% to 31% (mass fraction).This kind of alloy has a small tendency of white mouth, but requires high treatment temperature and large amount of slag after treatment.Nickel-magnesium alloy has been used in America and Europe. The advantages of these alloys are relatively high density, stable reaction, nickel can play an alloying role, and the price is high. This kind of alloy is seldom used in China.The pure magnesium alloy should be treated with special pressure and magnesium package. The magnesium absorption rate is high, but the treatment safety measures are very strict.

Rare earth is the spheroidizing agent used in the invention of nodular cast iron.The pri

Cast iron casting field:

      Magnesium content of 4%, 5%, 5.5% belong to the low magnesium spheroidizing agent, RE between 1% and 2%, mostly used in medium frequency furnace smelting, low sulfur iron solution spheroidizing treatment.It has the advantages of slow spherification and easy absorption of spherification elements.Magnesium content of 6%, 7% belong to the magnesium series spheroidizing agent, mostly used in cupola, electric furnace, or intermediate frequency furnace melting pearlescent shape cast nodular cast iron castings.According to the thickness of casting wall and sulfur content of raw iron, the appropriate amount of spheroidizing agent was determined.High magnesium series spheroidizing agent, suitable for cupola smelting, sulfur content of 0.06%-0.09% iron solution, the amount of addition between 1.6% and 2.0%.Low aluminum spheroidizing agent is used in castings which are prone to produce subcutaneous stomatal defects and castings which require aluminum content of iron liquid.The spheroidizing agent produced by pure Ce and pure La, after spheroidizing treatment, the iron liquid has few pure inclusions and the graphite ball is round.The spheroidizing agent produced by yttrium base weight rare earth is suitable for large section castings to delay spheroidization and prevent lumpy graphite.Sb spheroidizing agent is used in pearlite nodular cast iron.The low silicon spheroidizing agent is suitable for the foundry where a large number of return charge is used.Ni-mg spheroidizing agent is used in high nickel austenitic ductile iron.

Specification

grade

Mg

Ca

Si

Ba

Al

RE

Fe

3-8

7.0-9.0

2.0-3.0

39-44

 ≤ 1.0

2.0-4.0

BAL

5-8

7.0

1.5-2.5

39-44

 ≤1.0

4.0-6.0

BAL

7-8

7.0

1.5-2.5

39-44

 ≤1.0

6.0-8.0

BAL

T-2

7.0

2.5-3.0

39-45

1.5-2.5

 ≤1.0

2.5-3.5

BAL

EM-4

5.1-5.6

1.6-2.0

43-48

 ≤1.0

1.8-2.0

BAL

EM-5

5.5-6.8

0.8-1.2

44-48

 ≤1.0

0.8-1.2

BAL

EM-6

5.5-6.5

0.8-1.5

44

 ≤1.0

1.0-1.5

BAL