鎂合金薄壁件壓鑄成形的工藝及數值模擬

鎂合金薄壁件壓鑄成形的工藝及數值模擬Process and numerical simulation of high pressure die-casting magnesium alloy thin-wall parts

利用Procast模擬軟件分析AZ91D鎂合金薄壁手機支架件的充型過程與凝固過程；結合模擬與實驗研究不同工藝參數對薄壁壓鑄件表面質量、密度、組織及力學性能的影響，并探索出合適的工藝參數。結果表明：薄壁支架件所產生的缺陷類型及位置與模擬結果相吻合；澆注溫度和快壓射速度對薄壁件的壓鑄成形具有重要影響，適當降低澆注溫度或提高快壓射速度均有利于改善鑄件的表面質量，減少鑄造缺陷、細化晶粒和提高力學性能。對于AZ91D鎂合金薄壁手機支架件壓鑄，合適的澆注溫度和快壓射速度分別為670 ℃和2.3 m/s，在此工藝參數下生產的鑄件表面質量良好，晶粒細小，其平均尺寸僅為5.1 μm，鑄件密度高，氣孔率僅為2.0%，鑄件力學性能優異，其抗拉強度、屈服強度、伸長率和硬度分別為306 MPa、203 MPa、6.0%和86 HV。

The mold filling and solidification process of high pressure die-casting (HPDC) AZ91D magnesium alloy thin-wall phone bracket parts were simulated by Procast software. The effects of the different process parameters on the surface quality, density, microstructure and mechanical properties of thin-wall parts were studied by combining the simulation with experiment. The results show that the type and location of defects are identical with the simulated results. The pouring temperature and fast injection speed have an important effect on HPDC thin-wall parts of AZ91D magnesium alloy. Decreasing the pouring temperature or increasing the fast injection speed properly helps to improve surface quality, decrease casting defects and grain size and increase mechanical properties of parts. For HPDC thin-wall phone bracket parts of AZ91D alloy, suitable pouring temperature and fast injection speed are 670 ℃ and 2.3 m/s, respectively. Under the process parameters, the thin-wall parts have good surface quality, the average size of the grains is only 5.6 μm and the porosity level of the parts is only 2.0%. Also, the mechanical performance of the thin-wall parts is excellent, and the ultimate tensile strength, yield strength, elongation and hardness are 306 MPa，203 MPa，6.0% and 86 HV, respectively.

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