7A04铝合金超厚板的淬透性

采用万能力学试验机、光学显微镜、扫描电镜等手段,研究了7A04铝合金超厚板的显微组织、性能及淬透性。结果表明:225 mm厚的7A04铝合金热轧板材经过475 ℃×340 min的固溶淬火处理后,再进行120 ℃×24 h 时效,其表面的力学性能最好,抗拉强度为584 MPa,屈服强度为500 MPa,伸长率为11%;T/4厚度层力学性能最差,抗拉强度为396 MPa,屈服强度为257 MPa,伸长率为11%,强度与表面分别相差32%、49%。淬透深度为单面32 mm。通过调控化学成分、加大轧制压下量、增加淬火冷却速率等可改善板材表心力学性能之差,并提高淬透性。

Hardenability of 7A04 Al alloy super thick plate

The microstructure, properties and hardenability of the 7A04 Al alloy super thick plate were studied by means of universal mechanical testing machine, optical microscope and scanning electron microscope. The results show that when the 225 mm thick 7A04 Al alloy hot rolled plate is solid solution treated at 475 ℃ for 340 min with water quenching, then artificially aged at 120 ℃ for 24 h, the surface mechanical properties of the plate are the optimum, with the tensile strength, yield strength, and elongation being 584 MPa, 500 MPa, and 11%, respectively. However, the T/4 thickness layer gets the poorest property combination, with the tensile strength, yield strength, and elongation being 396 MPa, 257 MPa, and 11%, that is, the tensile strength and yield strength differ from that of the surface by 32% and 49%, respectively. The one-side quenching depth is 32 mm. By adjusting the chemical composition, increasing rolling reduction and increasing quenching cooling rate, the differences of mechanical properties between the plate surface and center can be improved, so is the hardenability.