# Cutting Speed and Feed Influence on Surface Microhardness of Dry-Turned UNS A97075-T6 Alloy
## 1 Introduction
Moreover, this thermal effect is more important in surfaces that present greater irregularities and, therefore, less superficial microhardness. On the other hand, 7000 aluminum alloy series have lower corrosion resistance compared to pure aluminum. Its main alloying element is Zn (-6%), which makes the appearance of the alumina protective layer (with higher corrosion resistance) more difficult [31]. For the 2000 and 7000 series, corrosion is usually localized, with the appearance of pitting common, as well as intergranular corrosion, which can be considered as the generation and nucleation points of microcracks that affect the continuity of the surface microstructure [32; 33; 34]. Despite the lack of research studying the cutting parameter influence on corrosion behavior of machined parts, several studies revealed that low cutting speed and high feed values result in machined parts with lower corrosion resistance [35; 36; 37]. In addition, the surface microhardness has a close connection with corrosion resistance. The metallic material corrosion resistance depends essentially on the ability to form passive bonded layers and its mechanical properties. Usually, higher hardness and tensile strength can be related to higher corrosion resistance [36; 38; 39]. [PERSON] et al. [40] studied the effect of the immersion corrosion process (saline solution 3.5% NaCl) in parts of the UNS A92009 alloy, machined using three different techniques: turned with ceramic tool, turned with diamond tip tool, and WEDM (wire electrical discharge machining). The results revealed that the samples machined by WEDM showed less corrosion resistance than the turned ones. The authors justified this result due to the greater surface irregularity obtained after WEDM machining. In addition, turned parts with the diamond tool were less affected by the corrosion process. [PERSON] at al. [41] evaluated the cutting parameters influence on the corrosion behavior of the UNS A92024-T3 aluminum alloy. After machining, the specimens were submerged in a saline solution (3.5% NaCl). Then, the surface finish after corrosion was compared with the initial one (after machining). The results showed that the use of lower feed and higher cutting speed resulted in a better corrosion resistance, as a consequence of the better surface quality of the machined parts. As shown in the literature review, there are several studies that related the cutting parameters to surface properties such as microhardness and corrosion resistance in dry-machined aeronautical aluminum alloys. However, few studies included the feed as a parameter of influence. This may be logical, keeping in mind that most of these studies were carried out at high cutting speed values (above 100 m/min), where thermal effects (mainly influenced by the cutting speed) predominate over mechanical effects, in which the feed has a greater influence. However, as previously mentioned, these alloys are frequently used hybridized with other materials, such as CFRP and Ti, which require the application of lower cutting speeds. In addition, in no case were the synergistic effects between cutting parameters, geometric alterations, microhardness, and corrosion resistance analyzed. Therefore, an analysis of cutting speed and feed influence on surface roughness and microhardness of UNS A97075-T6 alloy, turned under dry conditions, was carried out in this work. The results were compared before and after a corrosion process. The influence of these cutting parameters on each of these variables (surface roughness, microhardness, and corrosion resistance) was analyzed, as well as the possible interrelation between them.