Influence of Process Parameters and Sr Addition on the Microstructure and Casting Defects of LPDC A356 Alloy for Engine Blocks

Fan

2017

Journal of Engineering

This paper addresses the issue of unstable machining quality of large-scale high-precision internal combustion engine block; the key machining technologies of complex thin-wall internal combustion engine block are studied. This dissertation takes the L type engine block that is used as research object; the modular and fast changing fixtures have been designed for machining engine blocks; due to the fact that this kind of engine blocks has different number of cylinders, we establish a model of precision machining scheme based on virtual manufacturing technology and manufacturing method; on this basis, the scheme is applied to the actual production process to verify the feasibility of the program. The research shows that the precision machining scheme established based on virtual manufacturing technology can effectively solve the key machining technology of the engine block, and one purpose of using this method is to improve machining precision and efficiency of the assembly production. This study intends to propose final machining technology project of high-precision products, and this will formulate and gradually perfect a machining process framework for large engine block, which has engineering exploration value to promote machining technology.

Section: Introductionmentioning

confidence: 99%

Final Machining of Large-Scale Engine Block with Modularized Fixture and Virtual Manufacturing Technologies

Fan

2017

Journal of Engineering

“…The microstructure of the alloy investigated is shown in Figure . The alloy has no typical dendritic structure existing in hypoeutectic Al–Si alloys due to the existence of numerous second particles (Figure a) . It comprises of a matrix of α ‐Al, primary “blocky” Si, acicular eutectic Si, and several intermetallics, including Al 9 FeNi, Al 3 CuNi, and Al 5 Cu 2 Mg 8 Si 6 as shown in Figure b.…”

Section: Methodsmentioning

confidence: 99%

High‐Cycle Fatigue Behavior and Damage Mechanism of Multiphase Al–Si Piston Alloy at Room and Elevated Temperatures

et al. 2018

Microstructure evolution, tensile properties, fatigue crack initiation and propagation behaviors, and corresponding damage mechanisms of a multiphase cast Al-Si alloy used for pistons at room temperature (RT), 350 and 425 C are investigated. The results show that tensile and fatigue strengths decrease with the increase of temperature. Casting defects such as pores and oxide films are the most preferential sites for fatigue initiation at all the temperatures. The preferential propagation path for fatigue crack is mainly through the Al matrix and second phases at room temperature, through Al matrix at 350 C, and along grain boundary and phase/matrix interface at 425 C. This may be attributed to the reduction of strengths of matrix and phase/matrix interface at elevated temperatures. Relationship between fatigue strength and defect size is also discussed using critical stress intensity factor and probability distribution of defect size.

“…There is a long going discussion in the literature as to whether Sr modification increases pore formation or not [4][5][6][7][8][9]. Some researchers claimed that Sr addition alters the surface tension of the melt and thus enhances pore formation.…”

Section: Introductionmentioning

confidence: 99%

Sr addition and its effect on the melt cleanliness of A356

Atakav

Gürsoy

Erzi

et al. 2020

Mater. Res. Express

Strontium modification of Al-Si alloys has known to have several beneficial effects such as increased feedability, the formation of fibrous Si and increased mechanical properties. However, in the presence of Sr, during melting and holding durations, the oxide structure of the dross may change which leads to several problems during casting operations. In this work, the amount of Sr was changed and the melt was held for 1 h. Reduced Pressure Test (RPT) was used to asses melt quality change and it was found that cleanliness was increased due to the fading of Sr.