Sharif Digital Repository

Abstract: Shot peening is well-known process for mechanical properties integrity in metallic materials. In present study influences of different shot peening treatments on the surface hardness of different carbon steels were investigated experimentally and then alternative approach by using artificial neural network is presented for hardness prediction of the shot peened surface. After modeling a comprehensive parametric investigations and sensitivity analysis were applied according to the influence of the related effective parameters on surface hardness improvements. Graphic Abstract: [Figure not available: see fulltext.] © 2020, The Korean Institute of Metals and Materials  

Abstract: Shot peening is well-known process for mechanical properties integrity in metallic materials. In present study influences of different shot peening treatments on the surface hardness of different carbon steels were investigated experimentally and then alternative approach by using artificial neural network is presented for hardness prediction of the shot peened surface. After modeling a comprehensive parametric investigations and sensitivity analysis were applied according to the influence of the related effective parameters on surface hardness improvements. Graphic Abstract: [Figure not available: see fulltext.] © 2020, The Korean Institute of Metals and Materials  

Aluminum alloy series 5xxx lose their strength, especially in the heat affected zone (HAZ) of welds, due to thermal cycle during welding process. Because of this thermal cycle, re-crystallization and grain coarsening in HAZ occur, which result in decreasing of mechanical properties. In this paper the influence of "overloading" and "shot peening" as methods of post weld treatment on mechanical properties of AA5083 aluminum alloy welded joints is investigated. The results show that both overloading and shot peening treatments increase the hardness and tensile strength of welded joints. It is observed that the influence of overloading is stronger than shot peening on increasing hardness of the... 

The effects of nitriding, nitrocarburizing and shot peening on fatigue behavior of AISI D3 cold work tool steel were investigated. Five batches of fatigue specimens were manufactured according to the ASTM E466-96 standard. All specimens were quenched and tempered to a hardness of 50 HRC. One group of specimens was shot peened with an Almen intensity of 16 A, one group was nitrocarburized, one group was gas nitrided by single stage and another group was also nitrided by double stages. Rotating-bending fatigue tests were carried out. Our results showed that nitriding and nitrocarburizing treatments did not have a beneficial effect on the fatigue resistance of D3 tool steel. Fatigue test... 

The as-cast samples of FSX-414 Co-based superalloy were heat treated at the standard solution and aging heat treatment cycles. Specimens for joining were cut from the as-cast ingot. Transient liquid phase (TLP) bonding was carried out at the standard solution cycle, using MBF-30 interlayer. Also, bonded specimens were homogenized at the standard aging condition. The microstructure of the as-cast, heat treated and TLP bonded specimens were studied. These studies showed that the non-uniform distributed carbides of the as-cast specimen were replaced by uniform ones during the heat treatment. Eutectic M 23C 6 carbides were observed in all specimens. Due to the complete isothermal solidification,... 

Different microstructures were produced by heat treatment of 4340 steel. These microstructures are bainite, martensite, ferrite-martensite and ferrite-bainite. Mechanical tests were carried out at room temperature. The results showed that steel with bainite-ferrite microstructure has better ductility and charpy impact energy than steels with martensite-ferrite and full bainite microstructures. But yield and tensile strengths of this steel are less than the yield and tensile strengths of the other two steels. Hardness measurements showed that their hardness is the same. Fracture surface observations of tensile specimens showed increase in toughness of bainite-ferrite in comparison to... 

This paper presents the effect of martensite volume fraction (VM) on mechanical properties of AISI 4340 steel with ferrite-bainite-martensite microstructures. The steel bars were austenitized at 900°C for 1h followed by intercritical annealing at 740°C for 100min and quenching into a salt bath with temperature of 300°C and holding at different times to obtain triple phase (TP) microstructures with 34vol.% fraction ferrite and various martensite (or bainite) contents. Presence of three phases in adjacent to each other was confirmed by metallographic analysis and TEM studies. TEM observation also indicates higher density of dislocations within ferrite near martensite colonies compared to that...