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以HT250灰铸铁表面激光熔覆Al2O3陶瓷过程为研究对象,建立直接熔覆与梯度熔覆两种工艺下的数值模型,对其温度场、应力场进行定量研究。计算结果表明,在相同工艺参数情况下,梯度涂层能够达到更高温度,多层熔覆过程中热量呈累积趋势。灰铸铁基体与Al2O3陶瓷涂层界面两端易出现应力突变和拉应力集中,是裂纹萌生的危险部位。相比陶瓷直接熔覆,梯度熔覆能缓和材料参数差异的影响,有效降低界面及熔覆层的拉应力。
The Al2O3 ceramic process of HT250 gray cast iron was laser cladded. The numerical model of direct cladding and gradient cladding was established, and the temperature field and stress field were quantitatively studied. The calculation results show that under the same process parameters, the gradient coating can reach higher temperature, and the heat accumulation tendency in multi-layer cladding. Gray cast iron matrix and Al2O3 ceramic coating interface prone to sudden stress changes and tensile stress concentration is the danger of crack initiation site. Compared with ceramic direct cladding, gradient cladding can ease the influence of material parameter differences and effectively reduce the tensile stress of the interface and cladding layer.