This paper discusses whether laser technology holds promise for use in marking steel billets in a continuous-production environment. A laser-marking experiment was performed on “dull metal” and “bright metal,” which have different oxidation layers. The experiment was performed on rolled-shape samples produced using a wide variety of carbon steels and differing scale produced by using different cooling rates during heat treatment (in water, or in a furnace). A QR code or bar code was applied to the heat-treated samples using laser markers where the laser exposure and laser power used for application of the code were varied. The experimental results revealed significant technical difficulties preventing use of this technology with “dull metal” (application of the code to areas coated with scale causes the corresponding areas to change color — gray instead of bronze resulting in the code being impossible to read using standard equipment). Delamination of the oxide coating on the billet will lead to loss of code, and make the code impossible to subsequently read. Successful laser marking of “dull metal” requires initial preparation of the surface for marking in order to remove scale inclusions, so that the code will have uniform color and contrast. A clean surface requires less time to laser mark and lower laser-marker power because of the high contrast between the code and the surface. The code remained intact and readable after long storage (on the order of 9 months) under standard conditions.

中文翻译：

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使用激光打标机对钢坯进行补充打标

本文讨论了激光技术是否有望用于在连续生产环境中标记钢坯。对具有不同氧化层的“暗金属”和“亮金属”进行了激光打标实验。该实验是在使用各种碳钢生产的轧制样品上进行的，并且在热处理过程中（在水中或在炉中）使用不同的冷却速率生产的不同规模的样品。使用激光刻印机将二维码或条形码应用到热处理过的样品上，其中用于应用代码的激光曝光和激光功率是变化的。实验结果揭示了严重的技术困难，阻止了这项技术与“暗金属”的使用（将代码应用于涂有刻度的区域会导致相应区域的颜色发生变化——灰色而不是青铜色，导致使用标准设备无法读取代码）。钢坯上的氧化涂层分层会导致代码丢失，并且使代码无法随后读取。“暗金属”的成功激光打标需要对打标表面进行初步准备，以去除氧化皮夹杂物，从而使代码具有均匀的颜色和对比度。由于代码和表面之间的高对比度，干净的表面需要更少的激光标记时间和更低的激光标记功率。