CN108754300A - A kind of nuclear power position end cap QT500-7 casting and its casting method - Google Patents

Abstract

The invention discloses a kind of nuclear power position end cap QT500-7 casting and its casting method, the casting are as follows according to weight percent composition：Carbon：3.8-3.9, silicon 2.5-2.65, manganese 0.45-0.55, magnesium 0.035-0.045, surplus are iron and inevitable impurity；To obtain above-mentioned casting, production method includes the following steps：(1) Baking, (2) melting, (3) nodularization, (4) shell pour, (5) detection.The present invention provides cast member material and its techniques, are improved to technique, and the casting material being prepared has fabulous casting character and mechanical property, intensity is high, and the Room Temperature Creep limit is high, and stability is good, machinable performance is fine, and casting crack sensibility is small, there is good mobility, air-tightness and splitting resistance, and corrosion resisting property is strong, including resistance to surface corrosion and anticorrosion stress-resistant, impact flexibility is high, and elongation is high, castability is good, has a wide range of application.

Description

A kind of nuclear power position end cap QT500-7 casting and its casting method

Technical field

The present invention relates to high-performance metal materials field, be related to a kind of tensile strength, elongation percentage have stablize it is high performance

Background technology

Casting is that the mankind grasp than a kind of metal heat processing technique earlier, existing history in about 6000.China about exists The heyday of bronze casting is had been enter into before B.C. 1700- between 1000, quite high level is had reached in technique.Casting It is that liquid metals is cast in the casting cavity being adapted with part shape, after its cooled and solidified, to obtain part or hair The method of base.Mostly it was solid-state originally by casting material matter but was heated to the metal (example of liquid：Copper, iron, aluminium, tin, lead etc.), and mold Material can be sand, metal even ceramics.In response to different requirements, the method used would also vary from.Casting is to melt metal Be smelt and meet necessarily required liquid and pour into casting mold, through cooled and solidified, level processing after obtained predetermined shape, size and The technical process of the casting of performance.Cast blank achievees the purpose that exempt to be machined or process on a small quantity reduction because of almost forming Cost simultaneously reduces Production Time to a certain extent, and casting is one of the fundamental technology of modem devices process industry.

Spheroidal graphite cast-iron is widely used at present, in fields such as automobile making, aerospaces all by no small demand. Ferrite ductile cast iron matrix is ferritic spheroidal graphite cast-iron, has some strength, good impact flexibility and plasticity, can be by casting State or annealed acquisition.The form of metallographic structure graphite and metal elementary organization have a great impact to its toughness.(1) graphite shape The influence of state.Under metallic matrix tissue acceptance condition, graphite shape influences elongation and impact value very big：Flake graphite is tight It is in brittleness to have isolated metallic matrix, sharp corner stress concentration, therefore flake graphite cast iron again, and impact value is very low, and intensity is big It is big to weaken；And magnesium iron is then different, as long as elementary organization is qualified, Oxygen potential is cured high tenacity better.(2) influence of matrix.Iron For the matrix of ferritic spheroidal graphite cast iron based on ferrite, remaining is pearlite.Pearlite fraction increases, then under impact value and elongation Drop.Pearlite generally should be 10% hereinafter, and to disperse to exist, being influenced in this way on toughness little.

For chemical composition under the conditions of inoculated technology appropriate, ferritic content will be increased by improving carbon equivalent, thus be impacted Value, elongation rise therewith, but carbon equivalent is excessively high, easily cause graphite floatation.Graphite floatation is also fast with cooling with the thickness of casting Spend related, sand mold pours into a mould the casting of intermediate gauge (10~40mm), and as-cast ferrite ductile iron carbon equivalent, which takes, 4.4%~4.9% is Preferably, the carbon equivalent desirable 4.2%~4.8% of annealing iron element magnesium iron, thick strip reduce carbon equivalent, and thin smallclothes improve carbon equivalent.It adopts Carbon equivalent is also preferably reduced with intensive inoculation technique.

But the casting just produced is all more or less, and there is the weakness of the more crisp energy force difference that is hit, therefore usually It needs to be heat-treated spheroidal graphite cast-iron, has reached and eliminate cast-internal stress caused by due to expanding with heat and contract with cold, reduce machinery and add Deformation after work reduces case hardness, to improve machine-sensible conditions, improves its crystalline structure, enhancing Spherical Carbon crystallizes to be formed With stable effect.

Invention content

The object of the present invention is to provide the casting that a kind of performance stabilization, tensile strength, elongation percentage are far above general cast iron；This The another object of invention is to provide a kind of manufacturing method of the casting.

In order to achieve the above object, technical solution proposed by the present invention is as follows：

A kind of nuclear power position end cap QT500-7 casting, the casting are as follows according to weight percent composition：Carbon：3.8-3.9 Silicon 2.5-2.65, manganese 0.45-0.55, magnesium 0.035-0.045, surplus are iron and inevitable impurity.

A kind of casting method of nuclear power position end cap QT500-7 casting, production method include the following steps：

(1) Baking will be put into roaster in shell, temperature is controlled at 900-950 DEG C, and the burning stove time is 3h；

(2) melting, with intermediate frequency furnace or arc melting iron liquid, smelting temperature is 1500 DEG C -1530 DEG C, furnace charge choosing With silicon alloy cast iron, spheroidal graphite cast-iron, steel scrap；

(3) nodularization, spheroidising covers nodularization packet using pit type, after molten iron temperature reaches 1480 DEG C, carries out at nodularization Reason, first time molten iron discharging 3/5 wait for going out remaining 2/5 molten iron after spheroidizing reacion again；Nodulizer is magnesium-rare earth, nodularization temperature Degree control is at 1480 DEG C -1500 DEG C, and the spheroidizing reacion time is in 30S -55S；

(4) shell pours, and when carrying out spheroidising, shell is come out of the stove；Timely cast of skimming, cast temperature 1380 DEG C --- 1410 DEG C, casting time controls within 15S；Keep the temperature 6h, cooling room temperature die sinking；

(5) it detects；To with the single casting test block sampling after batch cast, checking chemical composition, metallographic structure, mechanical property.

The present invention has the following advantages compared with prior art：In order to solve existing QT500-7 machine-shaping nuclear power Position end cap will appear the manufacture requirement that intensity, elongation are inadequate, nuclear power position end cap is not achieved often, and the present invention provides cast members Material and its technique, are improved technique, and the casting material being prepared has fabulous casting character and mechanical property, by force Degree is high, and the Room Temperature Creep limit is high, and stability is good, and machinable performance is fine, and casting crack sensibility is small, there is good flowing Property, air-tightness and splitting resistance, and corrosion resisting property is strong, including resistance to surface corrosion and anticorrosion stress-resistant, impact flexibility are high, elongation Rate is high, and castability is good, has a wide range of application.

Specific implementation mode

Below in conjunction with specific embodiment, the present invention will be described in detail, and illustrative examples therein and explanation are only used for It explains the present invention, but is not intended as inappropriate limitation of the present invention.

Embodiment one

A kind of nuclear power position end cap QT500-7 casting and its casting method, casting are as follows according to weight percent composition：Carbon 3.8, silicon 2.5, manganese 0.45, magnesium 0.035, surplus is iron and inevitable impurity；To obtain above-mentioned casting, producer Method includes the following steps：

(1) Baking will be put into roaster in shell, temperature is controlled at 900 DEG C, and the burning stove time is 3h；

(2) melting, with intermediate frequency furnace or arc melting iron liquid, smelting temperature is 1500 DEG C, and furnace charge selects silicon alloy Cast iron, spheroidal graphite cast-iron, steel scrap；

(3) nodularization, spheroidising covers nodularization packet using pit type, after molten iron temperature reaches 1480 DEG C, carries out at nodularization Reason, first time molten iron discharging 3/5 wait for going out remaining 2/5 molten iron after spheroidizing reacion again；Nodulizer is magnesium-rare earth, nodularization temperature Degree control is at 1480 DEG C, and the spheroidizing reacion time is in 30S；

(4) shell pours, and when carrying out spheroidising, shell is come out of the stove；Timely cast of skimming, 1380 DEG C of cast temperature, Casting time controls within 15S；Keep the temperature 6h, cooling room temperature die sinking；

(5) it detects；To with the single casting test block sampling after batch cast, checking chemical composition, metallographic structure, mechanical property.

Embodiment two

A kind of nuclear power position end cap QT500-7 casting and its casting method, casting are as follows according to weight percent composition：Carbon 3.85, silicon 2.55, manganese 0.5, magnesium 0.04, surplus is iron and inevitable impurity；To obtain above-mentioned casting, production method Include the following steps：

(1) Baking will be put into roaster in shell, temperature is controlled at 930 DEG C, and the burning stove time is 3h；

(2) melting, with intermediate frequency furnace or arc melting iron liquid, smelting temperature is 1515 DEG C, and furnace charge selects silicon alloy Cast iron, spheroidal graphite cast-iron, steel scrap；

(3) nodularization, spheroidising covers nodularization packet using pit type, after molten iron temperature reaches 1480 DEG C, carries out at nodularization Reason, first time molten iron discharging 3/5 wait for going out remaining 2/5 molten iron after spheroidizing reacion again；Nodulizer is magnesium-rare earth, nodularization temperature Degree control is at 1490 DEG C, and the spheroidizing reacion time is in 40S；

(4) shell pours, and when carrying out spheroidising, shell is come out of the stove；Timely cast of skimming, 1385 DEG C of cast temperature, Casting time is controlled in 13S；Keep the temperature 6h, cooling room temperature die sinking；

(5) it detects；To with the single casting test block sampling after batch cast, checking chemical composition, metallographic structure, mechanical property.

Embodiment three

A kind of nuclear power position end cap QT500-7 casting and its casting method, casting are as follows according to weight percent composition：Carbon 3.88, silicon 2.6, manganese 0.5, magnesium 0.043, surplus is iron and inevitable impurity；To obtain above-mentioned casting, production method Include the following steps：

(1) Baking will be put into roaster in shell, temperature is controlled at 940 DEG C, and the burning stove time is 3h；

(2) melting, with intermediate frequency furnace or arc melting iron liquid, smelting temperature is 1520 DEG C, and furnace charge selects silicon alloy Cast iron, spheroidal graphite cast-iron, steel scrap；

(3) nodularization, spheroidising covers nodularization packet using pit type, after molten iron temperature reaches 1480 DEG C, carries out at nodularization Reason, first time molten iron discharging 3/5 wait for going out remaining 2/5 molten iron after spheroidizing reacion again；Nodulizer is magnesium-rare earth, nodularization temperature Degree control is at 1485 DEG C, and the spheroidizing reacion time is in 45S；

(4) shell pours, and when carrying out spheroidising, shell is come out of the stove；Timely cast of skimming, 1400 DEG C of cast temperature, Casting time is controlled in 12.5S；Keep the temperature 6h, cooling room temperature die sinking；

(5) it detects；To with the single casting test block sampling after batch cast, checking chemical composition, metallographic structure, mechanical property.

Example IV

A kind of nuclear power position end cap QT500-7 casting and its casting method, casting are as follows according to weight percent composition：Carbon 3.9, silicon 2.65, manganese 0.55, magnesium 0.045, surplus is iron and inevitable impurity；To obtain above-mentioned casting, producer Method includes the following steps：

(1) Baking will be put into roaster in shell, temperature is controlled at 950 DEG C, and the burning stove time is 3h；

(2) melting, with intermediate frequency furnace or arc melting iron liquid, smelting temperature is 1530 DEG C, and furnace charge selects silicon alloy Cast iron, spheroidal graphite cast-iron, steel scrap；

(3) nodularization, spheroidising covers nodularization packet using pit type, after molten iron temperature reaches 1480 DEG C, carries out at nodularization Reason, first time molten iron discharging 3/5 wait for going out remaining 2/5 molten iron after spheroidizing reacion again；Nodulizer is magnesium-rare earth, nodularization temperature Degree control is at 1500 DEG C, and the spheroidizing reacion time is in 55S；

(4) shell pours, and when carrying out spheroidising, shell is come out of the stove；Timely cast of skimming, 1410 DEG C of cast temperature, Casting time is controlled in 14.8S；Keep the temperature 6h, cooling room temperature die sinking；

(5) it detects；To with the single casting test block sampling after batch cast, checking chemical composition, metallographic structure, mechanical property.

The mechanical property tensile strength of QT500-7 in the prior art is 480-500Mpa/mm², elongation percentage 6%- again 8%；And the casting tensile strength 510-530Mpa/mm produced through the invention²；Elongation percentage 10%-15%.Far above existing skill Performance in art.

Above description is not limitation of the present invention, and the present invention is also not limited to the example above, the art The variations, modifications, additions or substitutions that technical staff is made in the essential scope of the present invention should also belong to the protection of the present invention Range.

Claims (2)

1. a kind of nuclear power position end cap QT500-7 casting, it is characterised in that：The casting is as follows according to weight percent composition：

Carbon：3.8-3.9, silicon 2.5-2.65, manganese 0.45-0.55, magnesium 0.035-0.045, surplus are iron and inevitable impurity.

2. a kind of casting method of nuclear power position end cap QT500-7 casting, it is characterised in that：Its production method includes the following steps：

(1) Baking will be put into roaster in shell, temperature is controlled at 900-950 DEG C, and the burning stove time is 3h；

(2) melting, with intermediate frequency furnace or arc melting iron liquid, smelting temperature is 1500 DEG C -1530 DEG C, and furnace charge selects silicon Alloy cast iron, spheroidal graphite cast-iron, steel scrap；

(3) nodularization, spheroidising covers nodularization packet using pit type, after molten iron temperature reaches 1480 DEG C, carries out spheroidising, the Molten iron discharging 3/5 waits for going out remaining 2/5 molten iron after spheroidizing reacion again；Nodulizer is magnesium-rare earth, the control of nodularization temperature At 1480 DEG C -1500 DEG C, the spheroidizing reacion time is in 30S -55S；

(4) shell pours, and when carrying out spheroidising, shell is come out of the stove；Timely cast of skimming, 1380 DEG C of cast temperature --- 1410 DEG C, casting time controls within 15S；Keep the temperature 6h, cooling room temperature die sinking；

(5) it detects；To with the single casting test block sampling after batch cast, checking chemical composition, metallographic structure, mechanical property.