火箭推进

为明晰航天高强不锈钢激光熔化沉积成形过程基础科学问题,推动其在航天液体火箭发动机领域的应用进程,针对航天高强不锈钢LMD成形过程中常见表面焊瘤、气孔、熔合不良等缺陷的形貌特征及产生机理进行深入分析,并提出对应的控制措施:通过优化边框扫描速度促进熔覆道的流动变形,极大减少了成形件侧表面及倾斜面的焊瘤缺陷; 使用PREP方法制备粉末材料替代当前GA法制备的粉末材料,成形试件孔隙率降低至0.1%以下,气孔缺陷基本消除; 采用提升“层间重熔能力”和减小相邻熔覆道间“沟壑”高度的方法,消除了成形件内部熔合不良缺陷。

In order to clarify the basic scientific problems of laser melting deposition forming process of aerospace high strength stainless steel,to promote its application in the field of aerospace liquid rocket engine,the defect types and mechanism of aerospace high strength stainless steel by laser melting deposition were analyzed. Besides,the corresponding control measures were put forward. First,the flow deformation of cladding channel was promoted by optimizing the scanning speed of border,the defects of weld nodules on the side surface and inclined surface of the formed part are greatly reduced.Second,the PREP method of powder preparation was used instead of the current GA method,the porosity of the formed specimen was reduced to less than 0.1%,and the stomatal defects were basically eliminated.Finally,the method of increasing the "layer remelting capacity" and decreasing the "gully" height between adjacent cladding channels was adopted,the defects of bad internal fusion were eliminated.

引言
1 试验设备及材料
2 结果与讨论
3 结论

图1 BLT-C1000型激光熔化沉积设备<br/>Fig.1 BLT-C1000 laser melting deposition equipment

图1 BLT-C1000型激光熔化沉积设备
Fig.1 BLT-C1000 laser melting deposition equipment

表1 CF-170高强不锈钢粉末化学成分<br/>Tab.1 Chemical components of CF-170 high strength stainless steel powder

表1 CF-170高强不锈钢粉末化学成分
Tab.1 Chemical components of CF-170 high strength stainless steel powder

图2 局部LMD试验件模型<br/>Fig.2 Local test model of LMD

图2 局部LMD试验件模型
Fig.2 Local test model of LMD

表2 CF-170高强不锈钢工艺试验参数<br/>Tab.2 Process test parameters of CF-170 high strength stainless steel

表2 CF-170高强不锈钢工艺试验参数
Tab.2 Process test parameters of CF-170 high strength stainless steel

图3 CF-170高强不锈钢成形工艺试验件<br/>Fig.3 Forming process sample of CF-170 high strength stainless steel

图3 CF-170高强不锈钢成形工艺试验件
Fig.3 Forming process sample of CF-170 high strength stainless steel

图4 工艺试验件内部CT扫描结果及熔合不良缺陷形貌<br/>Fig.4 CT scan results and bad fusion defect morphology of process sample

图4 工艺试验件内部CT扫描结果及熔合不良缺陷形貌
Fig.4 CT scan results and bad fusion defect morphology of process sample

图5 成形试样金相观察结果(放大倍数:25倍)<br/>Fig.5 Metallographic observation of formed samples(magnification:25)

图5 成形试样金相观察结果(放大倍数:25倍)
Fig.5 Metallographic observation of formed samples(magnification:25)

图6 类“S”形工艺试样<br/>Fig.6 S-shaped process samples

图6 类“S”形工艺试样
Fig.6 S-shaped process samples

图7 熔合不良缺陷形成原因<br/>Fig.7 Causes of bad fusion defects

图7 熔合不良缺陷形成原因
Fig.7 Causes of bad fusion defects

表3 消除熔合不良缺陷的优化工艺参数<br/>Tab.3 Optimize process parameters to eliminate bad fusion defects

表3 消除熔合不良缺陷的优化工艺参数
Tab.3 Optimize process parameters to eliminate bad fusion defects

图8 成形试样及CT扫描检测图<br/>Fig.8 Formed sample and CT scan detection chart

图8 成形试样及CT扫描检测图
Fig.8 Formed sample and CT scan detection chart

图9 试验用气雾化和旋转电极粉末<br/>Fig.9 Experimental gas atomization and rotating electrode powder

图9 试验用气雾化和旋转电极粉末
Fig.9 Experimental gas atomization and rotating electrode powder

图10 PREP粉末制备试样金相观察结果(放大倍数:25倍)<br/>Fig.10 Metallographic observation of samples prepared with PREP powder (magnification:25)

图10 PREP粉末制备试样金相观察结果(放大倍数:25倍)
Fig.10 Metallographic observation of samples prepared with PREP powder (magnification:25)

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备注

引言

1 试验设备及材料

2 结果与讨论

3 结论

期刊信息