An er/sc/zr composite micro-alloyed al-6mg-0.4mn alloy stabilization annealing process

A stabilization annealing and micro-alloying technology, applied in the field of heat treatment technology, can solve the problems that the mechanical properties and corrosion properties of the alloy cannot be satisfied at the same time, stabilization difficulties, intergranular corrosion, etc., to achieve good long-term intergranular corrosion resistance, widening Temperature range, the effect of improving the service life

Active Publication Date: 2017-06-09
BEIJING UNIV OF TECH
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Problems solved by technology

[0002] Al-6Mg is the plate with the highest Mg content used in the shipbuilding industry. Through the solid solution strengthening and deformation strengthening of Mg, it has almost the highest strength among Al-Mg alloys, but there are also prominent corrosion problems: solid solution Mg is unstable , especially when the Mg content exceeds 3.5wt.%, even if it is placed at room temperature for a long time, the β(Al3Mg2) phase will continue to precipitate along the grain boundaries, resulting in serious intergranular corrosion problems
As the Mg content increases, the stabilization temperature of the alloy is also higher. When the Mg content is greater than 6wt.%, the usual stabilization treatment alloy will inevitably undergo recrystallization, and the mechanical properties and corrosion properties of the alloy cannot be satisfied at the same time.
The difficulty of stabilization is also an important problem that limits the industrial application of Al-6Mg alloys

Method used

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  • An er/sc/zr composite micro-alloyed al-6mg-0.4mn alloy stabilization annealing process
  • An er/sc/zr composite micro-alloyed al-6mg-0.4mn alloy stabilization annealing process
  • An er/sc/zr composite micro-alloyed al-6mg-0.4mn alloy stabilization annealing process

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0019] 1) Taking Er / Sc / Zr composite microalloyed Al-Mg-Mn alloy as an example, the chemical composition is Mg5.5%~6.5%, Mn0.4%~0.5%, Zr0.1%~0.15%, Er0% ~0.09%, Sc0.04%~0.1% Unavoidable impurity content <0.4%, the alloy is homogenized annealed at 300°C (7-12h) + 475°C (15h), hot rolled at 450°C for 2h, hot rolled deformation The amount is about 70%, cold rolling after intermediate annealing at 475°C / 5h, and the final cold deformation amount is 60%±2%.

[0020] 2) The cold-rolled sheet obtained in step 1) was annealed at 240° C. for different times, and air-cooled to room temperature. According to the American Society for Testing and Materials standard AST G67, the nitric acid weight loss test was carried out on the cold-rolled and different annealed samples of the alloy, and the intergranular corrosion susceptibility of the material was evaluated by the weight loss per unit area of ​​the alloy before and after immersion. The change curve of weight loss per unit area with annea...

Embodiment 2

[0022] Step 1) is the same as in Example 1.

[0023] 2) The cold-rolled sheet obtained in step 1) was annealed at 265° C. for different times, and air-cooled to room temperature. According to the American Society for Testing and Materials standard AST G67, the nitric acid weight loss test was carried out on the cold-rolled and different annealed samples of the alloy, and the intergranular corrosion susceptibility of the material was evaluated by the weight loss per unit area of ​​the alloy before and after immersion. The change curve of weight loss per unit area with annealing time is as follows: figure 2 shown.

Embodiment 3

[0030] Step 1) Taking Er / Sc / Zr composite microalloyed Al-Mg-Mn alloy as an example, the chemical composition is Mg5.5%~6.5%, Mn0.4%~0.5%, Zr0.1%~0.15%, Er0 .09%, Sc0.1% unavoidable impurity content <0.4%, the alloy is homogenized annealed at 300°C (7-12h)+475°C (15h), hot rolled at 450°C for 2h, and the hot rolling deformation is about 70%, cold rolling after intermediate annealing at 475°C / 5h, until the final cold deformation is 60%±2%.

[0031] 2) After annealing the cold-rolled sheet obtained in step 1) at 240° C. for different times (10, 24 h), air-cool to room temperature.

[0032] 3) The annealed samples obtained in step 2) were annealed at 150° C. for different times. According to the American Society for Testing and Materials standard AST G67, the nitric acid weight loss test was carried out on the alloy samples in different annealed states, and the intergranular corrosion susceptibility of the material was evaluated by the weight loss per unit area of ​​the alloy bef...

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Abstract

The invention discloses a technique for stabilizing annealing of Er / Sc / Zr composite microalloyed Al-6Mg-0.4Mn alloy and belongs to the technical field of non-ferrous metal. The Er / Sc / Zr composite microalloyed Al-6Mg-0.4Mn alloy comprises, by mass, 5.5%-6.5% of Mg, 0.4%-0.5% of Mn, 0%-0.09% of Er, 0.1%-0.15% of Zr, 0.04%-0.1% of Sc and less than 0.4% of inevitable impurities. Homogenizing annealing is conducted on the Er / Sc / Zr composite microalloyed Al-6Mg-0.4Mn alloy at the temperature of 300 DEG C for 7-12 hours and at the temperature of 475 DEG C for 15 hours, hot rolling is conducted on the Er / Sc / Zr composite microalloyed Al-6Mg-0.4Mn alloy after the temperature is maintained to be 450 DEG C for two hours, and the hot rolling deformation is about 70%+ / -2%; cold rolling is conducted after intermediate annealing is conducted at the temperature of 475 DEG C for five hours till the final cold deformation is 60%+ / -2%; and then stabilizing annealing is conducted at the temperature of 240 DEG C for 10-24 hours, at the temperature of 250 DEG C for 5-24 hours and at the temperature of 265 DEG C for 2-24 hours. According to the technique, the precipitation position and the morphology of the beta phase are controlled through stabilizing treatment, and the long-term intercrystalline corrosion resistance of the alloy is improved. Meanwhile, high strength can be guaranteed, and the service life of a plate is remarkably prolonged.

Description

technical field [0001] The invention belongs to the technical field of nonferrous metals, in particular to a heat treatment process for stabilizing an Er / Sc / Zr composite microalloyed Al-6Mg-0.4Mn alloy resistant to long-term intergranular corrosion. Background technique [0002] Al-6Mg is the plate with the highest Mg content used in the shipbuilding industry. Through the solid solution strengthening and deformation strengthening of Mg, it has almost the highest strength among Al-Mg alloys, but there are also prominent corrosion problems: solid solution Mg is unstable , especially when the Mg content exceeds 3.5wt.%, even if it is placed at room temperature for a long time, the β(Al3Mg2) phase will continue to precipitate along the grain boundaries, resulting in serious intergranular corrosion problems. Therefore, for medium and high Mg content aluminum alloys with Mg content exceeding 3.5wt.%, stabilization treatment must be carried out to partially break and precipitate th...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C21/06C22F1/047
Inventor 高坤元郭姗姗聂祚仁丁宇升文胜平黄晖吴晓蓝
Owner BEIJING UNIV OF TECH
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