k. ranjbar

$X$-bar control charts are widely used to monitor and control business and manufacturing processes. Design of control charts refers to the selection of parameters, including sample size, control-limit width, and sampling frequency. Many researchers have worked on this issue and have also proposed various solutions. However, despite the numerous advantages, the proposed methods also have their own set of problems. The biggest challenge is the complexity of solving these issues. Due to the fact that optimal design of control charts can be formulated as a multi objective optimization problem, in this paper to solve this problem, we used initial solution Spider's web data envelopment analysis method. In previous methods used multiple algorithms to resolve the issue. But in the proposed method once using Data Envelopment Analysis method and without any other algorithm can solve multi objective problem and this method can yield desirable efficient. Lastly, we compare our method with others and demonstrate its application in a real industrial context.

This research studied the effect of two-stage over aging treatment on the 17-4 PH stainless steel corrosion behavior. First, the steel was solution annealed at 1035 °C for 1h, then it was subjected to a two-stage over aging treatment known as H1150-M treatment. Hydrogen induced cracking and stress corrosion cracking standard tests were carried out under annealed and over aged conditions. Microhardness tests were conducted to evaluate the mechanical properties under different testing conditions. Microstructural examinations were performed by the optical microscope and field emission scanning electron microscope. The results showed that under annealed condition, the microstructure consisted of lath and coarse martensite and interdendritic δ-ferrite that transferred to severely tempered and layered martensite after over aging treatment with the formation of reversed austenite. In the latter case, the reversed austenite was about 26% compared to 7% before over aging treatment. Under the hydrogen induced cracking test, the over aged 17-4 PH steel exhibited no cracking, unlike the annealed condition. The results also showed that 17-4 PH steel under both annealing and over aging conditions, is suspectable to stress corrosion cracking; meanwhile, time to failure was substantially higher in the latter condition.

In this study, Inconel 617 alloy was welded to A387-Gr.11 low-alloy steel using ER309L filler metal via gas tungsten arc welding (GTAW). First, the corrosion behavior of Inconel 617, A387-Gr, and the weld metal was evaluated by the Tafel polarization test and electrochemical impedance spectroscopy (EIS) in acidic (H2SO4), neutral (NaCl), and combined (H2SO4 + NaCl) solution at ambient temperature. The results of polarization and EIS measurements in all corrosive solutions indicate that the corrosion resistance decreases from 617 alloy to weld metal and from weld metal to low-alloy steel, respectively. The Comparison of the polarization curves of the base metals and the weld metal showed susceptibility to galvanic corrosion between Inconel 617 / weld metal in 1M NaCl solution. The behavior of galvanic corrosion of this pair was evaluated using the mixed potential theory and the electrochemical noise measurement. The results showed that in a galvanic couple of alloy 617 / weld metal, the weld metal acts as anode and corrodes in such a way that its corrosion rate increases from 0.22 μA/cm2 before joining to 1 μA /cm2 after joining.

Dissimilar welding of API 5L X80/DSS 2250 steels was carried out using PCGTAW process. The welds were produced using three types of filler metals (ER2209, ER309L and KJS-124). The microstructural investigations showed that the microstructure of ER2209 weld metal is duplex (ferrite and austenite) and ferrite content changes from root pass (35%) to cap pass (41%). It was revealed that the solidification mode of ER309L weld metal was ferritic-austenitic mode and its microstructure has an austenitic matrix with skeletal ferrites and smaller amount of vermicular ferrites along the grain boundaries. Ferrite scope results revealed that ferrite content of root pass (6%) is less than the final pass (10%). Microscopic results showed that the microstructure of KJS-124 weld metal consists of grain-boundary, Widmanstätten and acicular ferrites with martensite-austenite islands. Epitaxial growth was detected in the interfaces of ER309L/DSS 2209 ، ER2209/DSS 2205 and KJS-124/API 5L X80 and unmixed zones and type II boundaries were detected in the ER2209/API 5L X80- ER309L/API 5L X80 and KJS-124/DSS 2205 interfaces. The results of impact and hardness tests revealed that ER2209, ER309L and KJS-124 weld metals have the best toughness and the KJS-124, ER2209 and ER309L filler metals got the highest hardness, respectively.