Cooling rate as a process parameter in advanced roll forming to tailor microstructure, mechanical and corrosion properties of EN AW 7075 tubes

Abstract

The effects of solution heat treatment parameters and quench media as a processing tool for tailoring microstructure, mechanical and corrosion properties in roll forming of EN AW 7075 alloy were studied. The highest yield stress and ultimate tensile strength were obtained for the specimens quenched in water, while the air‐cooled specimens exhibited inferior mechanical properties. Microstructural analysis of specimens showed that except water‐quenched specimens, the parts cooled/quenched in oil, in direct contact with tool steel and air are characterized by coarse precipitates and precipitate‐free zones. The corrosion tests showed that the cooling rate has a pronounced influence on the corrosion resistance and related mechanism of EN AW 7075 alloy. The surfaces of specimens quenched in water remained intact although pitting corrosion took place. The microstructure of the part processed by roll forming was explored in direct comparison. It is revealed that by the employment of quenching nozzles, a high cooling rate similar to the water‐quenched condition can be achieved. Results obtained in the present study pave the way to directly tailor aluminum parts for specific applications.

A Comparative Study on the Production of a Hat Profile by Roll Forming and Stamping

“…The influence of different quenching rates on the mechanical properties of the AA7075 alloy is discussed in ref. [5]. To achieve high strength, the quenching rate must be high enough.…”

“…Different quenching rates after solution annealing (SA) lead to different mechanical properties. [5,6] HF of AA7075 in the context of this study is HF and die quenching with cold or heated tools. During HF, the forming temperature is reported to be in the range of the SA temperature of the AA7075 alloy.…”

“…Different quenching rates after solution annealing (SA) lead to different mechanical properties. [ 5,6 ]…”

Fatigue Strength Assessment of Laser Beam Welded Joints Made of AA7075 and Magnetic Pulse Welded Joints Made of AA7075 and 3D‐Printed AlSi10Mg

“…An important example among the wrought alloys is the AA7075 alloy, as it has one of the highest strengths up to R m = 550-600 MPa. [1][2][3] AA7075 is classically used for highly stressed components in aeronautic applications and aircraft construction [1,4,5] and to a limited extent in automotive applications. [6][7][8] Although the high-strength aluminum-zinc alloy AA7075 has the double tensile strength compared to the widely used aluminum alloys of the 6000 class, it is rarely considered in welded constructions due to its low weldability.…”