三光束激光熔覆工艺参数对熔覆层几何特征影响

The Influence of Process Parameters on Geometry Characteristics by Three Beams Laser Cladding

采用"三光束光内同轴送丝"激光熔覆新方法研究可以获得表面质量较高单道熔覆层的工艺参数组合方案。建立三光束激光熔覆工艺参数与熔覆层表面形貌关系以及几何特征变化规律的数学模型,通过激光提供的单位能量密度E1与丝材所需的能量密度E2之间比值关系判断熔覆层表面形貌状态,工艺参数和熔覆层几何特征关系的数学模型预测熔覆层几何特征变化规律,并采用单因素试验法进行验证。研究结果如下:E1/E2<1,熔池能量"不足",1.1≥E1/E2≥1.0,熔池能量处于"不足"到"充足"过渡阶段,以及E1/E2>1.6,熔池能量"过剩",这三种情况形成的熔覆层表面质量较差;只有当1.5≥E1/E2>1.1,熔池能量"充足"能够充分熔化进入熔池的丝材,且丝材能够以连续平稳的"搭桥过渡"方式熔入熔池,熔覆层表面连续光滑,质量较高;熔覆层几何特征变化规律:数学模型预测值变化趋势与试验值基本吻合,离焦量减小,熔覆层宽度W减小,高度H增大,宽高比a减小;激光功率增大,熔覆层宽度W增大,高度H减小,宽高比ɑ增大。扫描速度增大,熔覆层宽度W减少,高度H减少,宽高比a略有增加。送丝速度增大,熔覆层宽度W和高度H都会增大,宽高比ɑ减小。综上采用"三光束光内同轴送丝"新方法对不锈钢304材料的丝材和基材进行激光熔覆试验,工艺参数组合方案满足1.5≥E1/E2>1.1,可以制备出表面形貌佳熔覆层。

In order to obtain better combination scheme of process parameters of single cladding layer with high surface quality, a new forming method of "coaxial wire feeding inside three beams" is used. Mathematical model of relationship between process parameters of layer cladding and the surface morphology is established, between process parameters and geometric characteristics. The surface morphology state of cladding layer is judged by the ratio between the unit energy density provided by the laser E1 and the required energy density of wire E2.The mathematical model of the relationship between the process parameters and the geometric characteristics of cladding layer is used to predict the variation law of the geometric characteristics, and the single factor test method is used to make experimental verification. The experienced state of cladding layer surfacemorphology is that:E1/E2< 1, the molten pool energy is "insufficient",1.1≥E1/E2≥1.0, the energy of molten pool is in the transition stage from "insufficient" to "sufficient", E1/E2> 1.6, the energy of the molten pool is "excess", the surface quality of the coating formed in these three cases is poor. Only when 1.5≥E1/E2>1.1, the "sufficient" energy of the molten pool can fully melt the wire, which can be melted into the molten pool in a continuous and stable way, the surface of cladding layer is continuously smooth and the quality is high. The variation law of cladding layer geometric characteristics: the predicted value of the mathematical model is in good agreement with the experimental value, the defocusing amount decreases, the width W decreases, the height H increases, and the ratio of width to height ɑ decreases. Laser power increases, the width W increases, the height H decreases, and the ratio of width to height ɑ increases. Scanning speed increases, the width W decreases, the height H decreases, and the ratio of width to height ɑ increases slightly. Wire feeding speed increases, the width W and height H increases, and the ratio of width to height ɑdecreases. Conclusion is that: make laser cladding test of stainless steel 304 wire and substrate by using new forming method of "coaxial wire feeding inside three beams", selecting reasonable process parameters scheme, which meet 1.5≥E1/E2>1.1, better surface morphology can be achieved.