Aluminum Alloy/Steel Liquid-solid Compound Casting And The Performance Of The Interface

With the development of lightweight constructions, application ofcomposite material becomes one of the main research direction of current industrial area. In this paper, combined with the actual factory producing of piston, steel and aluminum solid-liquidcompound casting process was studied.The cast aluminum alloypiston tends to crack by the thermal stress in the actual workingenvironment. In order to prevent this situation,the aluminum/steelliquid-solid compound casting process is used. However,thebonding between the dissimilar metals of steel and aluminum isnot easy to control, and the metallurgical bonding of theinterface will be the focus and difficulty.The paper gives aresearch for the operation of the solid-liquid diffusion bonding ofthe steel and aluminum, provides an optimized discussion andtheoretical support for the technology of the metallurgicalbonding of the steel sheet and the aluminium-alloy piston in theDiesel Engine Piston. The focus lies on the surface treatment ofQ235steel substrate, the solid-liquid diffusion-bonding processand the investigation of the interfacial structure andperformance of Q235/ZL109bimetal.The natural oxide layer is easily formed on the suface of thesteel in atmospheric environment.In this paper,the ultimateobjectives of the aluminum/steel liquid-solid compound project isto get the metallurgical bonding between the aluminum andsteel. The oxide layer will severely prohibit the diffusion bondingbetween aluminum and steel and bring a large number ofimpurities into the interface, thus the strength and quality of thebimetal will be reduced. In order to eliminate the naturaloxidation of the steel and prevent the secondary oxidation in theprocess of the aluminum/steel compound casting, the paperstudies the surface treatment of Q235steel substrate includingthe hot-dip galvanizing after pickling and electrochemicalgalvanization process. In order to prevent the secondary oxidation of the substrateduring the compound casting and get a good metallurgicalbonding, the paper mainly researches by controlling the financepressure, the casting temperature, the preheating temperature,the holding time and other parameters and analyzes the samplewith different process parameters. The analysis results show thatthe sample with the Ni-Cu coating、preheating time90s、holdingtime90s、compound casting temperature730℃gets the bestperformance.According to the best process parameters, the aluminumalloy pistons (ZL109) and anti-cracking steel bars (DC01)compound materials in the actual plant production of dieselengine are tested,the results show that the performance of thebiemetal is excellent.The test results show that the surface wettability ofZL109/Q235could be effectively improved by the surfacetreatment of the Q235steel substrate; It is necessary for themetallurgical bonding of Q235and ZL109to adjust thepre-heating temperature and time of the Q235substrates. TheNi-Cu plating surface treatment can significantly improve thewettability of the bi-metallic samples and prevent from thesecondary oxidation. The compound interface of the compoundQ235(700℃)/ZL109(730℃) is metallurgically bonding, which’sinterface organized as α-Fe， α-Al， FeAl3, Fe2Al5intermetalliccompounds, and the thickness of it could be controlled in15μmto20μm to significantly improve the shear strength. The practicalproduction in factories using the technology parameters meetsthe requirements.