CN1986860A

CN1986860A - Cast iron nodulizer and nodulizing process

Info

Publication number: CN1986860A
Application number: CN 200610097856
Authority: CN
Inventors: 张青来
Original assignee: Jiangsu University
Current assignee: Jiangsu University
Priority date: 2006-11-16
Filing date: 2006-11-16
Publication date: 2007-06-27

Abstract

The cast iron nodulizer and nodulizing process relates to casting technology. The cast iron nodulizer contains metal Mg powder in 30-70 wt%, MgO in 18-60 wt% and adhesive, such as phenolic resin, in 10-12 wt%. During the nodulizing process, the dispersed mixture is solidified at 250-300 deg.c and added into molten iron at 1350-1450 deg.c through one bell process before desulfurizing and nodulizing. Through inoculation, the graphite nodules are fine and round. By means of the cast iron nodulizer and nodulizing process of the present invention, low silicon and high strength aluminum nodular cast iron may be obtained.

Description

Cast iron nodulizer and nodulizing process

Technical field

The present invention relates to casting field, promptly belong to the cast iron spheriodization process thereof, this technology can be applied in the small serial production of high-strength ironcasting.

Technical background

Nodular iron casting is widely used in the field of automobile, machine and equipment manufacturing, and producing spheroidal graphite cast iron is various with the nodulizing agent kind.At present, main aborning the application contains the master alloy of magnesium, rare earth as nodulizing agent.Also there are some other nodulizing agents, as pure magnesium, magniferous mechanical mixture.Selection nodulizing agent and nodulizing process depend primarily on the performance of working condition, foundry goods etc.

Patent CN86105963 is a kind of method for cast-iron spheroidazation that utilizes pure magnesium to make nodulizing agent.MAG block is placed in the clad, and the slit between MAG block and the refractory brick bag wall dashes real with refractory materials, and a MAG block only face can contact with molten iron, during spheroidizing, utilize subcontractor to make 180 ° of hot metal ladle upsets, treat that MAG block melts fully, gasifies after, the hot metal ladle of overturning repeatedly again.Shortcoming is to need special-purpose hot metal ladle.

The main chemical compositions of patent CN85100068 nodulizing agent is: Mg5～10%; Re0～2%; Si0～10%, surplus are iron.Nodulizing agent (CN91108271.9) composition is: Mg5-9%, and Re0.5-3%, Ca3.5-5.0%, Ba1.5-4.5%, Si35-50%, Bi0.5-4.5%, all the other are iron.Contain a large amount of elements except that MAGNESIUM METAL in the nodulizing agent, serious restriction obtains low silicon spheroidal graphite cast iron.

The magnesium agglomerate of compression moulding carried out desulfurization with pouring method to cast iron as sweetening agent after patent CN92105974.4 mixed with metal magnesium powder (or bits) and iron powder (or bits).This technology is applicable to the production of single-piece and short run part large-scale ductile iron spare.Its shortcoming is that sweetening agent contains a large amount of Fe, will cause the molten iron fast cooling.

(№ 1398405 for Russ P, C21C, 1/10.) mixture of metallic particles magnesium and iron silicon alloy is put into the bottom of tundish, for the specific absorption that improves MAGNESIUM METAL with prevent that metal from splashing, cover steel scrap above it, pouring molten iron is carried out spheroidizing then.The MAGNESIUM METAL granular size is that 0.05～0.145mm and iron silicon alloy size are 0.05～1.0mm in this mixture.Adopt metal magnesium powder and iron silicon alloy mixture to carry out spheroidizing, in molten iron, add in the MAGNESIUM METAL, be accompanied by the increase of silicone content, silicone content surpasses 10～20 times that add the MAGNESIUM METAL amount in the mixture, molten iron silicon content after the spheroidizing surpasses 1.0%, can't obtain the low high-strength cast iron of silicon (Si≤0.6%).In addition, the nodularization mixture only contains 9% MAGNESIUM METAL, has increased the quantity of nodularization mixture greatly, also will cause the molten iron fast cooling.

In a word, the shortcoming of pure metal magnesium nodulizing process be need specific equipment, prepare in the middle of the overlong time of casting ladle, and can't to a small amount of molten iron (≤50Kg) carry out spheroidizing and waste is serious.And utilizing master alloy cast iron to be carried out spheroidizing as nodulizing agent, the molten iron silicon content after the processing increases, and is not suitable for producing the low high-strength spheroidal graphite cast iron of silicon.

Summary of the invention

According to above situation, the magnesium compound that contains that the purpose of this invention is to provide a kind of that do not contain element silicon and rare earth element makes the method for cast iron nodularization as nodulizing agent, and it can guarantee to obtain the meehanite cast iron of different silicon-containing amount.

Cast iron nodulizer is characterized in that: by 30～70% metal magnesium powders, 18～60%MgO and 10～12% binding agents (as resol) are formed, and the metal magnesium powder granular size is 0.05～0.145mm.

The cast iron nodulizer of even dispersion is cured at 250～300 ℃, adds molten iron by the bell jar method then in the time of 1350～1450 ℃, carries out spheroidizing.

The invention has the advantages that: the nodulizing agent of being recommended contains 70% MAGNESIUM METAL, does not have metal to splash, and the nodularization effect can guarantee to obtain the meehanite cast iron of different silicon-containing amount as pure magnesium, particularly handles a small amount of molten iron.

Description of drawings

Fig. 1 is the process block diagram of the embodiment of the invention.

Fig. 2 is the bell jar structure and the mixture structural representation of the embodiment of the invention

The 1-bell jar; 2-metallic particles magnesium; 3-MgO; The height of H-bell jar; The diameter of D-bell jar

Embodiment

The present invention is described in more detail below in conjunction with the drawings and specific embodiments.

Provide the result of different tests molten iron spheroidizing in table 1～3.

Molten iron is in the non-vacuum induction furnace fusing of 20Kg or 50Kg.The chemical ingredients of the pig iron: 3.70%C, 0.51%Si, 1.70%Al, 0.60%Mn, 0.10%P, 0,04%S.The preparation of nodularization mixture: with 60% metal magnesium powder, 28%MgO, behind the 12% phenolic resin adhesive uniform mixing, curing, sintering under 300 ℃.Molten iron is melting, and be superheated to 1400 ℃, after the slagging-off of surface, utilize the bell jar method that cut-and-dried nodularization mixture is added in the molten iron.After liquid metal stops bubbling, take out bell jar, slagging-off and cast.

Group element ratio (embodiment 1～embodiment 9) in order to optimize the nodularization mixture still adopts the identical pig iron, its chemical ingredients: 3.70%C, 0.51%Si, 1.70%Al, 0.60%Mn, 0.10%P, 0,04%S.The weight of molten iron remains 20Kg.By the MgO ratio rice control MAGNESIUM METAL after the adjustment calcining and the speed of response of molten iron.

Shown in table 1 and 2, the nodularization mixture of embodiment 1～embodiment 4 schemes can guarantee that the nodularization process is steady, does not have metal to splash, and little metal magnesium just can make 80～90% spheroidization of graphite.

In order safely cast iron nodulizer to be added in the molten iron, must be cured and sintering at 250～300 ℃ in advance.The nodularization mixture that is lower than 250 ℃ of sintering preparations is contacting with molten iron, carries out discharging a large amount of gases in the spheroidizing process, slows down the nodularization process greatly, reduces magnesium absorption rate (embodiment 10).When comparatively high temps carried out sintering, fierce oxidation took place in a large amount of MAGNESIUM METAL in air, increased the consumption of MAGNESIUM METAL and reduced nodularization effect (embodiment 9).

Can reach best effect in the spheroidizing of 1350～1450 ℃ of temperature range cast iron.To follow the specific absorption of MAGNESIUM METAL to reduce at lesser temps (embodiment 8) or at comparatively high temps (embodiment 7) spheroidizing molten iron, this is because the MAGNESIUM METAL evaporative process time is long or explosion phenomenon at high temperature appears in MAGNESIUM METAL.

Not siliceous nodularization mixture can guarantee constant (table 3) of molten iron at the silicone content of nodularization process medium cast iron, and this has enlarged the method for cast-iron spheroidazation technology possibility of application widely, and guarantees to obtain the low high-strength aluminium spheroidal graphite cast iron of silicon.

Table 1

Spheronization process	Example	Mixture constituent element content, % weight				The mixture solidified temperature, ℃	The molten iron spheroidization treatment temperature, ℃	The spheroidizing time, cek.	The spheroidizing process
		Mixture constituent element content, % weight								Mg	MgO	Binding agent	FeSi75
		Recommending MgO excessive Mg excessive nodularization excess Temperature nodularization temperature to cross the low too high solidification temperature of solidification temperature crosses low known	Enforcement 1 enforcement 2 enforcements 3 enforcements 4 enforcements 5 enforcements 6 enforcements 7 enforcements 8 enforcements 9 enforcements 10 compare 11	30 30 70 40 15 80 50 30 30 30 9	60 59 18 50 80 12 39 59 59 59 -					Mg	MgO	Binding agent	FeSi75	10 11 12 10 5 8 11 11 11 11 -	- - - - - - - - - - 91	250 275 300 275 300 300 300 300 350 200 -	1350 1400 1450 1400 1400 1400 1480 1320 1400 1400 1400	150 175 210 195 160 220 170 260 180 240 240	Stable stable reaction intense reaction is fierce stable

Table 2

Example	Add mixture quantity, %	Remain Mg content in the cast iron, %	Magnesium absorption rate, %	The spheroidization of graphite rate, %	Casting quality
Example	Add mixture quantity, %	Remain Mg content in the cast iron, %	Magnesium absorption rate, %	The spheroidization of graphite rate, %	Casting quality	Enforcement 1 enforcement 2 enforcements 3 enforcements 4 enforcements 5 enforcements 6 enforcements 7 enforcements 8 enforcements 9 enforcements 10 compare 11	0.30 0.29 0.13 0.23 0.58 0.18 0.19 0.29 0.29 0.29 0.88	0.072 0.073 0.071 0.074 0.070 0.072 0.043 0.052 0.030 0.061 0.070	80 84 78 81 80 50 45 60 35 70 80	90 90 90 90 90 85 50 55 10 65 80	Zero defect zero defect zero defect zero defect zero defect zero defect zero defect zero defect zero defect zero defect zero defect

Table 3

Example	The content of silicon in the cast iron, %
	The content of silicon in the cast iron, %		Before the spheroidizing	After the spheroidizing
	Implement 1 enforcement, 3 enforcements 4 and compare 11	0.51 0.51 0.51 0.51	Before the spheroidizing	After the spheroidizing	0.51 0.51 0.51 1.60

Claims

1, cast iron nodulizer is characterized in that: based on the mass percent example, by 30～70% metal magnesium powders, 18～60%MgO and 10～12% binding agents are formed.

2, cast iron nodulizer according to claim 1 is characterized in that: the metal magnesium powder granular size is 0.05～0.145mm.

3, use the spheronization process of the described cast iron nodulizer of claim 1, it is characterized in that: with the described cast iron nodulizer even dispersion of claim 1, be cured at 250～300 ℃, in the time of 1350～1450 ℃, add molten iron then, carry out spheroidizing by the bell jar method.