Lubrication-free deep drawing with metal matrix composite (MMC) tool surfaces leads to scores and grooves due to particle penetration into the formed sheet metal, and results in high local contact pressure in the radius of the deep drawing tool. To improve on this, the ratio of contacting area to total area must locally be increased in high-load regions of the tool surface. Multi-stage laser melt injection (LMI) and local laser particle fusion (LLPF) were carried out to increase the hard particle content of the MMC tool surfaces. LLPF is a novel two-step LMI process whereby hard particles are locally fused together under additional powder feeding after a regular LMI. The resulting nugget was shown to grow in height and width with an increase in the pulse duration. The substrate temperature prior to the particle fusion had an influence on the defect-free nugget growth. Whilst the chemical composition of the fused tungsten carbide (FTC) nuggets was similar to FTC particles, their hardness was slightly reduced compared to literature values for tungsten carbide. For the first time, FTC nuggets could be successfully applied on MMC tool surfaces to realize an increased hard coating area.

中文翻译：

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局部激光粒子融合：融合硬粒子以降低 MMC 工具表面的高接触压力

使用金属基复合材料 (MMC) 工具表面进行无润滑深冲会由于颗粒渗透到成型的金属板中而导致划痕和凹槽，并导致深冲工具半径中的局部接触压力较高。为了改善这一点，必须在工具表面的高负载区域局部增加接触面积与总面积的比率。进行多级激光熔体注射 (LMI) 和局部激光粒子融合 (LLPF) 以增加 MMC 工具表面的硬粒子含量。LLPF 是一种新颖的两步 LMI 工艺，在常规 LMI 之后，硬颗粒在额外的粉末进料下局部融合在一起。结果表明，随着脉冲持续时间的增加，所得金块的高度和宽度都会增加。粒子融合前的衬底温度对无缺陷熔核生长有影响。虽然熔融碳化钨 (FTC) 熔核的化学成分与 FTC 颗粒相似，但与碳化钨的文献值相比，它们的硬度略有降低。首次将 FTC 金块成功应用于 MMC 工具表面，以实现增加的硬涂层面积。