CN102560269A

CN102560269A - Exhaust manifold of engine with cast heat-resistant steel

Info

Publication number: CN102560269A
Application number: CN2010105794926A
Authority: CN
Inventors: 高文刚; 杨民江; 赵极椿; 朱力良; 焦淑杰
Original assignee: JIAMUSI CHANGTONG AUTO PARTS GROUP CO Ltd
Current assignee: JIAMUSI CHANGTONG AUTO PARTS GROUP CO Ltd
Priority date: 2010-12-09
Filing date: 2010-12-09
Publication date: 2012-07-11

Abstract

An exhaust manifold of an automotive engine is in poor working conditions, and the heated characteristics comprise large temperature difference between the surface temperature and the inner cavity temperature, frequent heat cycle impact of high temperature air flow, adverse weather conditions in driving, and the like, therefore, the exhaust manifold of the automotive engine is expected to have good medium-high temperature mechanical performance and use performance. The invention provides the exhaust manifold of the automotive engine, which is produced by cast heat-resistant steel. In the cast heat-resistant steel used for producing the exhaust manifold of the automotive engine, nickel is reduced, precious alloy elements such as niobium etc. are not used, and a small amount of aluminum and trace amounts of rare earth, vanadium and titanium are added, so that the use performance of the cast heat-resistant steel is greatly improved and the cast heat-resistant steel can be used at the temperature lower than 1100 DEG C. With the adoption of the exhaust manifold, the production cost is greatly reduced, and the exhaust manifold is ensured to have good performance. The exhaust manifold of the automotive engine is ensured to have long service life when being produced by the cast heat-resistant steel.

Description

A kind of casting heat-resistant steel enmgine exhaust

Affiliated technical field

The present invention relates to a kind of casting heat-resistant steel enmgine exhaust, especially relate to a kind of automobile engine with supercharger use and can bear the pyritous exhaust manifold.

Background technology

Since oil engine came out, problems such as the performance of the used material of exhaust manifold, life-span received various countries material supplier author's attention always; The residing operating mode of enmgine exhaust is abominable, it is different from that general heat-resistant piece bears be basically evenly, constant high temperature, its characteristics of being heated show that the temperature difference is big; Surface temperature is at 150 ℃～200 ℃, and interior cavity temperature is greater than 900 ℃, and the thermal cycle impact of high temperature gas flow is frequent; And harsh climate condition or the like in going, this just makes enmgine exhaust should have good middle high-temperature mechanical property and use properties, like hot strength; Toughness, thermal fatigue, high temperature creep-resisting property; Anti-oxidant growth property etc. are the comprehensive criterions of mechanical property and use properties.

Along with industrialized development, human protection pay attention to day by day to living environment, American-European countries particularly USA in recent years improves constantly automobile exhaust emission standard.Reach emission standard, must be in the convertor of mover injecting catalyst, make it reach working temperature fast, by heat, otherwise it becomes a heat sink to exhaust manifold, weakens the action effect of catalyzer with enough fast speed.

American-European developed country motor car engine has experienced common grey iron with the exhaust manifold material, high-strength gray cast iron, common magnesium iron, vermicular cast iron, stainless steel, the such process of high silicon molybdenum ductile iron.High silicon molybdenum ductile iron becomes the selection of production high-performance exhaust manifold in industrial circles such as automobile; The discharge manifold of Ford, Kleist company 70% is produced with high silicon molybdenum ductile iron at present, and Ge Laide-Le Baite motor corporation, Berlin Foundry Inc. have also promoted the application of high silicon molybdenum ductile iron on the automobile engine to exhaust menifold in succession.

China's enmgine exhaust has experienced by common grey iron with material, high-strength gray cast iron, common magnesium iron, vermicular cast iron evolution.Most of at present vermicular cast iron production enmgine exhaust that uses.

In recent years, Japan has developed a kind of ferritic stainless steel and has been used to produce enmgine exhaust, and new steel grade not only thermotolerance is strong, but also possesses the formability of height.The composition of new steel grade is 19%Cr, 0.3%Si, 1.5%Nb, 1.%Mo.

Along with the employing of new technologies such as the reinforcement of exhaust regulation and supercharging technology, it is higher that exhaust temperature becomes, and reached 980 ℃, and material in the past can't adapt to.

A kind of austenitic stainless steel has been invented by Germany, and the composition of new steel grade is 20%Cr, 38%Ni, 1.5%Nb, be used to produce enmgine exhaust.New steel grade can bear the high temperature more than 1100 ℃.But the rare valuable alloying element of new steel grade uses also many than the past, and production cost is very high.

Summary of the invention

Incompatible in order to overcome existing production enmgine exhaust material capability, or the more high deficiency of cost, the present invention provides a kind of production cost lower, the casting heat-resistant steel enmgine exhaust that performance is higher.The technical solution adopted for the present invention to solve the technical problems is:

Select for use a kind of production cost lower, the higher high temperature steel of performance is used to produce enmgine exhaust.The characteristics of this high temperature steel are:

1, reduces nickel or do not use valuable alloying element such as niobium;

2, add REE.

Adding REE can reduce sull distortion and rimose tendency and can make the pit in the sull protrusion of surface diminish, tail off significantly. and add REE in alloy with the microalloying element form, can significantly improve the antioxidant property of alloy under harsh service condition.

3, add an amount of aluminium, but should series high temperature steel major advantage on its high-temperature oxidation resistance, the Al203 protective membrane that alloy surface generates under the high temperature is fine and close, firm and do not have a volatility, its sull still has advantages of higher stability in 1200～1250 ℃.

4, add vanadium titanium crystal grain thinning.

The invention has the beneficial effects as follows: reduce or do not use valuable alloying element to reduce production costs, the rare earth, aluminium, vanadium, the titanium that add trace improve use properties.

Description of drawings

Accompanying drawing is that melting furnace charge of the present invention adds process flow sheet.

Embodiment

Chemical component weight per-cent of the present invention (%) is:

C：0.3～0.5，Cr：18～22，Ni：23～26，Al：3～5，V：0.2～0.5，

Ti:0.05～0.2, RE:0.1～0.2, surplus is Fe.

In medium-frequency induction furnace, drop into furnace charge by the accompanying drawing order; Add iron, road iron, electrolytic nickel at first in proportion; After iron, road iron, electrolytic nickel melt fully, add aluminium, molten iron temperature is brought up to 1460～1480 ℃ after with slag removal; Add vanadium iron, ferrotianium and rare earth alloy then, and pour in the casting mold of enmgine exhaust.

Claims

1. an automobile engine to exhaust manifold is characterized in that the automobile engine to exhaust manifold that adopts the casting heat-resistant steel to produce.

2. automobile engine to exhaust manifold according to claim 1 is characterized in that the chemical component weight per-cent (%) of casting heat-resistant steel is: C:0.3～0.5, Cr:18～22; Ni:23～26, Al:3～5, V:0.2～0.5; Ti:0.05～0.2, RE:0.1～0.2, surplus is Fe.