THE EFFECT OF SHOT PEENING AND CORROSION ON THE CRITICAL BUCKLING LOAD OF THE 304 STAINLESS STEEL COLUMNS

Abstract

ABSTRACT Machine part exposed to an axial compressive load is called strut, but a vertical strut is known as a column. The machine members that must be investigated for column action include connecting rods, piston rods, screw jack, etc. If a column is exposed to a compressive load and this load being slowly augmented, a stage will attain if the column will be exposed to an ultimate load. After that, the column will collapse via crushing and the load will be recognized as a (crushing load). When the column is short or intermediate, the column fails sometimes in bending, and when the column is long, it fails in buckling. The value of buckling load is low for long columns and is relatively high for intermediate columns. The present investigation focuses on testing and evaluation of columns (samples) using (304) stainless steel used in many engineering industries and will choose 24 samples (12 dry samples and 12 samples submerged in sea water for 90 day) with and without shot peening (SP). The buckling behavior of axial compressive load has been studied experimentally and theoretically using Euler and Rankin theories and Solidworks program. For evaluating the dangerous failure, a laser electrical devise was used, and in the case of bending reaching to 1% of specimen length, the specimen reached the failure. The results obtained from this study indicated that the column, whose slenderness ratio (SR) is higher than 120, is referred to long column, and the Euler theory can be successfully used. But, when (SR) is lower than 120, the column is known as an intermediate column, and the Rankine theory can be successfully used. The mechanical properties evinced a reduction due to wear modes and reasonable improvement when using v shot peening. The results obtained empirically without any treatment for the two conditions; without shot peening (WSP) and with shot peening (SP) that have been compared with the theoretical equations of Euler as well as Rankin. Such theories manifested an overestimation of the critical buckling loads. The factor of safety of 3 and 2.5 respectively made the experimental and theoretical results in good agreement. The mechanical properties of 304 stainless steel were increased after 15 min of quenching by using shoot peening by (2.08 and 5.9) for Ultimate Stress and Yield Stress, respectively, including increasing the critical torsion load by (24- 30%) for long columns and (2-6%) for medium columns. The effect of corrosion on the mechanical properties of the samples was studied, and its influence was noted by a decrease in the values of Ultimate Stress and Yield Stress by 2.08 and 5.9, respectively and for unhardened samples by 8.39 and 8.5, respectively. The size of corrosion was also calculated using the weight loss method and Tafel method. The effect of tempering on the corrosion volume was observed, with an improvement rate of 90.14%.