铝青铜表面激光熔覆镍基合金温度场的数值模拟

Numerical simulation of temperature field of laser melt-cladding of Ni-based alloy on surface of aluminum-bronze

以铝青铜为基材、铜镍合金为熔覆粉末,采用压粉方式实现激光熔覆加工.对此过程建立二维温度场数值模型,考虑温度变化对铝青铜热物理参数的影响以及表面对流换热、内部结晶潜热等因素,用C++语言编写激光熔覆过程中温度场模型的计算程序.结果表明,激光熔覆加工过程中的温度场变化是由非稳态到达稳态的过程,激光光斑附近温度梯度较大,远离光斑处温度梯度较小.由温度场分布图得知,为优化加工质量,满足熔覆要求,试验应采用由高到低的功率进行熔覆.

Taking the aluminum bronze as matrix material and copper-nickel alloys as cladding powder, the processing of laser melt-cladding was implemented with pressurized powder method. A two-dimension- al numerical model of temperature was set up for this process, where the effects of temperature change on thermcrpbysical parameters of aluminum bronze, the surface convective heat transfer, and the internal latent heat of crystallization were taken into consideration. C＋＋ language was used to prepare a program for evaluating the temperature field with laser cladding process model. The result showed that in laser cladding process whole temperature field changed from non-steady-state to steady-state, and near laser spot there was a larger temperature gradient. Temperature gradient was smaller away from the laser spot. The diagram of temperature distribution showed that in order to get optimal quality of cladding and meet the cladding requirements, the cladding should be conducted with a power from high to low.