ABSTRACT

The susceptibility of additively manufactured (AM) and heat-treated Alloy 718 to hydrogen embrittlement was compared to that of wrought Alloy 718. Specimens were prepared from laser powder bed fusion (LPBF) coupons built with the long axis in the x-direction (horizontal printing) and with the long axis in the z-direction (vertical printing). Despite the heat treatment, coupons printed horizontally demonstrated retained elongated grains parallel to the build, z-direction, while the coupons printed vertically had a relatively uniform and small grain structure perpendicular to the build direction, but a highly elongated grain structure parallel to the build direction. Slow strain rate testing under standardised cathodic charging conditions in 0.1 M H₂SO₄ indicated a greater susceptibility to hydrogen embrittlement of the test specimens manufactured from coupons printed horizontally, attributed to cracks more readily propagating along the elongated direction of the microstructure.

摘要

将增材制造 (AM) 和热处理合金 718 对氢脆的敏感性与锻造合金 718 的敏感性进行了比较。 样品是从激光粉末床熔融 (LPBF) 试样制备的，其长轴为x方向（水平方向）打印）和长轴在z方向（垂直打印）。尽管进行了热处理，水平打印的试样仍保留了平行于构建、z方向的细长晶粒，而垂直打印的试样具有与构建方向垂直的相对均匀和较小的晶粒结构，但具有平行于构建的高度细长的晶粒结构方向。在 0.1 MH 标准阴极充电条件下的慢应变率测试₂ SO ₄表明由水平打印的试样制成的试样对氢脆的敏感性更大，这是由于裂纹更容易沿微观结构的伸长方向传播。