Smelting flame-proof protection method for magnesium alloy

Abstract

The invention provides a flame retarding protective method used in magnesium alloy smelting, which comprises the steps of introducing a mixed gas comprising 1, 1, 1, 2, 3, 3, 3-heptafluoropropane (HFC-228ea) gas and diluting gas into a magnesium alloy smelting furnace at the same time of smelting magnesium alloy to conduct flame retarding protection of magnesium alloy until the smelting and casting are finished. The used HFC-228ea gas has the advantages of low greenhouse effect, extremely low toxicity under working concentration, nearly no influence to human body, high quality, high efficiency, and environmental friendliness. The inventive method solves the environmental, equipment and human body damage problems when protecting magnesium alloy smelting with high-greenhouse effect SF6 and toxic SO2 used in the current international magnesium industrial community; and has the advantages of simple process, distinct environment and economic benefits, and applicability to industrial application.

Description

technical field

[0001] The invention belongs to the technical field of magnesium alloy metallurgy, and further relates to a flame-retardant protection method for magnesium alloy smelting. Background technique

[0002] Magnesium alloy not only has low density, high specific strength and high specific stiffness, but also has the advantages of good damping performance, good cutting performance, good electrical conductivity, stable size, low cost, no pollution, and easy recycling. It has been widely used in fields such as aviation and aerospace, and is one of the important lightweight and high-strength materials in the 21st century. However, some key technologies that hinder the large-scale application of magnesium alloys have not been resolved, such as magnesium alloys are prone to oxidative combustion during smelting, processing and heat treatment. For many years, people have been looking for ways to prevent oxidative combustion during the melting of magnesium alloys. At pre...

Examples

Embodiment 1

[0010] Magnesium alloy AZ91D was smelted in a resistance crucible furnace with a volume of 25 liters and a melting temperature of 700°C using 0.15% HFC-227ea and 99.85% N 2 The mixed gas, the feeding rate of the mixed gas is 1L per minute (about 5% of the closed gas volume above the surface of the magnesium melt), and the magnesium alloy smelting gas protection is carried out.

[0011] Put the dried charge (3 kg) into the crucible of the resistance crucible furnace, and cover the crucible lid. Turn on the melting furnace, heat the crucible, the heating rate is 10°C / min, and feed the mixed gas at 200°C, the mixed gas composition is 0.15% HFC-227ea and 99.85% N 2 The mixed gas, the feed rate of the mixed gas is 1L / min and heated up to melting, the protective gas quickly forms a dense and well-protective protective film on the surface of the magnesium melt, and continues to heat up to 700°C after melting, Keep warm for 1 hour, then pour. During the whole smelting and heat prese...

Embodiment 2

[0013] Magnesium alloy AZ91D is smelted in a resistance crucible furnace, the volume of the smelting furnace is 25 liters, the melting temperature is 680°C, a mixed gas of 0.2% HFC-227ea and 99.8% dry compressed air is used, and the feeding rate of the mixed gas is 0.8 L per minute (approx. 4% of the closed gas volume above the surface of the magnesium melt), the magnesium alloy smelting gas protection is carried out.

[0014] Put the dried charge (3 kg) into the crucible of the resistance crucible furnace, and cover the crucible lid. Turn on the melting furnace, heat the crucible, the heating rate is 10°C / min, and feed the mixed gas at 200°C, the mixed gas composition is a mixed gas of 0.2% HFC-227ea and 99.8% dry compressed air, and the amount of the mixed gas is 0.8L / min heating up to melting, the protective gas quickly forms a layer of dense and good protective protective film on the surface of the magnesium melt, after melting, continue to heat up to 680°C, keep it warm ...

Embodiment 3

[0016] Magnesium alloy AM50 is smelted in a resistance crucible furnace, the volume of the smelting furnace is 25 liters, the melting temperature is 730 ° C, and a mixed gas of 0.3% HFC-227ea and 99.7% dry compressed air is used, and the feeding rate of the mixed gas is 1.0 L per minute (approx. 5% of the closed gas volume above the surface of the magnesium melt), the magnesium alloy smelting gas protection is carried out.

[0017] Put the dried charge (3 kg) into the crucible of the resistance crucible furnace, and cover the crucible lid. Turn on the melting furnace, heat the crucible, the heating rate is 10°C / min, and feed the mixed gas at 200°C, the mixed gas composition is 0.3% HFC-227ea and 99.7% dry compressed air, the flow rate of the mixed gas is 1.0L / min, heat up After melting, the protective gas quickly forms a dense and well-protective protective film on the surface of the magnesium melt. After melting, continue to heat up to 730°C, keep it warm for 1 hour, and then...

technical field

[0001] The invention belongs to the technical field of magnesium alloy metallurgy, and further relates to a flame-retardant protection method for magnesium alloy smelting. Background technique

[0002] Magnesium alloy not only has low density, high specific strength and high specific stiffness, but also has the advantages of good damping performance, good cutting performance, good electrical conductivity, stable size, low cost, no pollution, and easy recycling. It has been widely used in fields such as aviation and aerospace, and is one of the important lightweight and high-strength materials in the 21st century. However, some key technologies that hinder the large-scale application of magnesium alloys have not been resolved, such as magnesium alloys are prone to oxidative combustion during smelting, processing and heat treatment. For many years, people have been looking for ways to prevent oxidative combustion during the melting of magnesium alloys. At pre...

Examples

Embodiment 1

[0010] Magnesium alloy AZ91D was smelted in a resistance crucible furnace with a volume of 25 liters and a melting temperature of 700°C using 0.15% HFC-227ea and 99.85% N 2 The mixed gas, the feeding rate of the mixed gas is 1L per minute (about 5% of the closed gas volume above the surface of the magnesium melt), and the magnesium alloy smelting gas protection is carried out.

[0011] Put the dried charge (3 kg) into the crucible of the resistance crucible furnace, and cover the crucible lid. Turn on the melting furnace, heat the crucible, the heating rate is 10°C / min, and feed the mixed gas at 200°C, the mixed gas composition is 0.15% HFC-227ea and 99.85% N 2 The mixed gas, the feed rate of the mixed gas is 1L / min and heated up to melting, the protective gas quickly forms a dense and well-protective protective film on the surface of the magnesium melt, and continues to heat up to 700°C after melting, Keep warm for 1 hour, then pour. During the whole smelting and heat prese...

Embodiment 2

[0013] Magnesium alloy AZ91D is smelted in a resistance crucible furnace, the volume of the smelting furnace is 25 liters, the melting temperature is 680°C, a mixed gas of 0.2% HFC-227ea and 99.8% dry compressed air is used, and the feeding rate of the mixed gas is 0.8 L per minute (approx. 4% of the closed gas volume above the surface of the magnesium melt), the magnesium alloy smelting gas protection is carried out.

[0014] Put the dried charge (3 kg) into the crucible of the resistance crucible furnace, and cover the crucible lid. Turn on the melting furnace, heat the crucible, the heating rate is 10°C / min, and feed the mixed gas at 200°C, the mixed gas composition is a mixed gas of 0.2% HFC-227ea and 99.8% dry compressed air, and the amount of the mixed gas is 0.8L / min heating up to melting, the protective gas quickly forms a layer of dense and good protective protective film on the surface of the magnesium melt, after melting, continue to heat up to 680°C, keep it warm ...

Embodiment 3

[0016] Magnesium alloy AM50 is smelted in a resistance crucible furnace, the volume of the smelting furnace is 25 liters, the melting temperature is 730 ° C, and a mixed gas of 0.3% HFC-227ea and 99.7% dry compressed air is used, and the feeding rate of the mixed gas is 1.0 L per minute (approx. 5% of the closed gas volume above the surface of the magnesium melt), the magnesium alloy smelting gas protection is carried out.

[0017] Put the dried charge (3 kg) into the crucible of the resistance crucible furnace, and cover the crucible lid. Turn on the melting furnace, heat the crucible, the heating rate is 10°C / min, and feed the mixed gas at 200°C, the mixed gas composition is 0.3% HFC-227ea and 99.7% dry compressed air, the flow rate of the mixed gas is 1.0L / min, heat up After melting, the protective gas quickly forms a dense and well-protective protective film on the surface of the magnesium melt. After melting, continue to heat up to 730°C, keep it warm for 1 hour, and then...