Heat treatment process for scandium-containing Al-Zn-Mg-Cu base squeeze casting aluminum alloy

Abstract

The invention belongs to the field of aluminum alloy heat treatments, and particularly relates to a heat treatment process for a scandium-containing Al-Zn-Mg-Cu base squeeze casting aluminum alloy. The heat treatment process adopts a three-stage strengthening solid-solution treatment process and a single-stage aging treatment process, wherein the three-stage strengthening solid-solution treatment comprises: carrying out thermal insulation for 24 h at a temperature of 460 DEG C, heating to a temperature of 470 DEG C, carrying out thermal insulation for 8 h, continuously heating to a temperature of 480 DEG C, carrying out thermal insulation for 2 h at a temperature of 480 DEG C, immediately taking, and carrying out water quenching, and then the single-stage aging heat treatment is performed and comprises: carrying out thermal insulation for 24 h at a temperature of 120 DEG C. According to the present invention, the coarse non-equilibrium phase in the alloy can be sufficiently dissolved and homogenized, the supersaturation degree of the solid solution is increased, the stress concentration tendency with the grain boundary eutectic phase is reduced, the matrix structure after aging is fine GP zones distributed in a diffusion manner and an eta<,> phase, the grain boundary is a grain boundary precipitation phase distributed in a discontinuous manner, the ultra high strength ([sigma]s is more than or equal to 500 MPa) is achieved, and the good plasticity (delta is more than or equal to 10%) is provided.

Description

technical field [0001] The invention belongs to the field of heat treatment of aluminum alloys, in particular to a heat treatment process of Al-Zn-Mg-Cu series extrusion casting aluminum alloys containing scandium. Background technique [0002] Lightweight requirements in the fields of aviation and automobiles have promoted the research and development of high-strength and tough aluminum alloys. As the deformed aluminum alloys with the best strength and toughness, the application field of 7XXX series aluminum alloys has gradually expanded from aerospace to civilian fields. Some structurally complex parts It is also expected to be made of 7XXX-series deformed aluminum alloys. The resulting increase in processing costs and increased difficulty in the process hinders the further expansion of its application range. At present, the strength of cast aluminum alloys suitable for casting is generally low. Among them, the aluminum-copper alloy ZAl205A is the strongest cast aluminum a...

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Problems solved by technology

[0002] Lightweight requirements in the fields of aviation and automobiles have promoted the research and development of high-strength and tough aluminum alloys. As the deformed aluminum alloys with the best strength and toughness, the application field of 7XXX series aluminum alloys has gradually expanded from aerospace to civilian fields. Some structurally complex parts It is also hoped to be made of 7XXX series deformed aluminum alloys. The resulting increase in processing costs and difficulty in the process hinders the further expansion of its application range.

At present, the strength of cast aluminum alloys suitable for casting is generally low. Among them, the aluminum-copper alloy ZAl205A is the strongest cast aluminum alloy. After T6 treatment, the ultimate tensile strength can reach 510MPa, which has not yet reached the ultra-high strength level. Therefore, how to Realizing the ultra-high strength of 7XXX series deformed aluminum alloys under casting conditions has become one of the hotspots in the development and application of high-performance aluminum alloys

[0003] The composition characteristics and solidification characteristics of the 7XXX series Al-Zn-Mg-Cu alloy determine the essential defect of poor casting performance, and the alloy is not suitable for conventional casting

On the other hand, the increase of solution temperature and the prolongation of solution time will lead to MgZn 2 The coarsening of the particles and the growth of the matrix will lead to a decrease in the strength of the alloy

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