| As to the strengthening of the internal-combustion engine valve end, the present manual spraying weld technology and applied welding material are experimentally surveyed. Its disadvantages and limitations are further analyzed for the practical application. Therefore, special welding material is designed in composition and apparent shape, trying to get new material with better performance and low cost, according to the true serving condition. Accordingly, special welding method is selected and welding technique parameters are tested, to be fit for the auto weld technology.By the thermodynamics and metallographic theory, new Fe-Ni-Co weld material is worked out and experimented, to replace the present Ni60 and Stallie1. Test results show: with Fe-Ni-Co, the working face hardness is HRC53-56 after process; the joint intensity is above 30 Kg/mm2. The structure of weld layer is austenite with solution strength, distributed by strengthening compound phases. Fe-Ni-Co is better than Ni60 on the capability of shock resistance and flake resistance, but low cost. During the optimizing design of composition, the content of B is decreased to be2-2.5 and Si 1-2 wt%, which not only reduces the material brittleness, but preserves the weld performance with the parental 21-4N material. Argon arc weld and high frequency weld are tested in the experiments. Argon arc weld is proved with better comprehensive characteristics than high frequency weld, with respects of the structure stability, within-control, and more economical. Furthermore, on the condition of argon arc weld, a number of experiments have been conducted, to inspect how the structure of the weld layer, fusion zone, and heat affected zone, are affected by the welding parameters, such as welding power, time, and positions. Some regularity has been found. The key technique parameters ranges have been attained to be the base data for the auto weld. Fe-Ni-Co is certificated to be feasible for the valve end strengthening.
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