Strain Life of Shot Peening AA 2024-T4

Abstract

<span style="font-family: Times New Roman; font-size: small;"> </span><p class="MsoNormal" style="margin: 0in 0in 4pt; text-align: justify; line-height: 12pt; mso-line-height-rule: exactly;"><span style="font-family: "Times New Roman","serif"; font-size: 10pt; mso-ascii-theme-font: major-bidi; mso-hansi-theme-font: major-bidi; mso-bidi-theme-font: major-bidi;">This research involved studying the effect of shot<span class="hps"><span style="color: #333333;"> </span></span>peening, by steel balls, on Low Cycle Fatigue<span class="hps"><span style="color: #333333;"> </span></span>(LCF) of<span class="hps"><span style="color: #333333;"> </span></span>aluminum<span class="hps"><span style="color: #333333;"> </span></span>alloy<span class="hps"><span style="color: #333333;"> </span></span>AA 2024-T4 at different peening times (5, 10, 15, 20 &amp; 30 min.). Shot<span class="hps"><span style="color: #333333;"> </span></span>peening helped<span class="hps"><span style="color: #333333;"> </span></span>to increase <span class="hps"><span style="color: #333333;">t</span></span>he tensile and yield strength (?_u, ?_y) to reach the highest values at the time of 15 minutes<span class="hps"><span style="color: #333333;"> </span></span>and then declined.</span><span style="font-size: 10pt;"><span style="font-family: Calibri;"> </span></span><span style="font-family: "Times New Roman","serif"; font-size: 10pt; mso-ascii-theme-font: major-bidi; mso-hansi-theme-font: major-bidi; mso-bidi-theme-font: major-bidi;">Strain hardening coefficient (n)<span class="hps"><span style="color: #333333;"> </span></span>increased to some extent, which recorded an indication of<span class="hps"><span style="color: #333333;"> </span></span>the possibility of continued cyclic hardening behavior of the alloy during<span class="hps"><span style="color: #333333;"> </span></span>LCF after the<span class="hps"><span style="color: #333333;"> </span></span>peening. LCF tests showed that un-peened AA 2024-T4 was more resistant</span><span style="font-size: 10pt;"><span style="font-family: Calibri;"> </span></span><span style="font-family: "Times New Roman","serif"; font-size: 10pt; mso-ascii-theme-font: major-bidi; mso-hansi-theme-font: major-bidi; mso-bidi-theme-font: major-bidi;">especially at rates lower than 9x10³ cycles, then for<span> </span>15 min. shooting, a pronounced improvement<span class="hps"><span style="color: #333333;"> </span></span>in LCF<span class="hps"><span style="color: #333333;"> </span></span>life down to the number of cycle’s equal to10⁵ cycles. SEM showed that the size of<span class="hps"><span style="color: #333333;"> </span></span>dimples, length of secondary cracks and the voids increased for peened specimens<span class="hps"><span style="color: #333333;"> </span></span>were especially at high cyclic strains near the strains of ?_u.<strong></strong></span></p><span style="font-family: Times New Roman; font-size: small;"> </span

Experimental Investigation on the Effects of Surface Mechanical Attrition Treatment on the Surface of the Aluminum Alloy

“…In this case, the indents are created deeper on the surface because a position that is repeatedly shot should be distorted larger. Comparing this result with the research of Abood et al [14] and Trung et al [15], a good agreement of the effect of shot peening time on the surface roughness of the shot peened material is achieved.…”

Fretting-Fatigue Analysis of Shot-Peened Al 7075-T651 Test Specimens

“…The red line is a power law fitted to the results showing that if the observed behavior is extrapolated to lower lives, there would not be any improvement with the use of the shot-peening treatment around 1000 cycles. This statement is in agreement with previously published works dealing with the performance of shot-peened parts at a low cycle regime [45,46]. This can also be seen when representing the data in a different format.…”

Surface, Subsurface and Tribological Properties of Ti6Al4V Alloy Shot Peened under Different Parameters

“…Fundamentally being a mechanical surface treatment, shot peening is a complicated process, in which many parameters affect the process performance [ 20 , 49 , 50 , 51 ]. These can be classified into four main groups [ 52 ]: (1) shot characteristics (size [ 20 , 33 , 34 , 53 , 54 , 55 ], type [ 34 , 55 ], shape, density [ 34 ], hardness [ 34 , 53 ], and yield strength [ 20 , 33 , 34 , 52 , 53 , 54 , 56 , 57 ]); (2) process parameters [ 34 ] (shot flow rate, shot pressure [ 20 , 54 , 57 , 58 ], shot speed [ 59 ], impact angle [ 59 , 60 ], nozzle-to-target distance [ 60 ], nozzle diameter, and shot peening duration [ 20 , 32 , 60 , 61 ]); (3) target material properties (mechanical properties [ 34 ] such as hardness, yield strength, toughness, chemical composition and crystal structure [ 20 , 62 ]); and (4) environmental factors (temperature and humidity) [ 53 , 63 ]). Yildiran et al reported that the surface roughness and hardness of Ti6Al4V alloy might significantly vary depending on shot size and peening pressure [ 5 ].…”