Phase transformation temperatures and Fe enrichment of a 22MnB5 Zn-Fe coated steel under hot stamping conditions
Phase transformation temperatures and Fe enrichment of a 22MnB5 Zn-Fe coated steel under hot stamping conditions
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DOI：
10.1016/j.jmrt.2019.11.003
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发表时间：
2020-01-01
影响因子：
6.4
通讯作者：
da Silva Dias, Fabio Moreira
中科院分区：
文献类型：
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作者：
da Costa Ximenes, Daniel Alexandre;Moreira, Luciano Pessanha;da Silva Dias, Fabio Moreira
在过去的几年里，冲压淬火钢成功地为汽车工业做出了贡献，通过制造轻量化的车身部件，在提高乘客安全性的同时，成功地满足了降低燃油消耗和严格的温室气体排放的日益严格的法规。锌-铁涂层是防止腐蚀甚至提高这些钢的耐腐蚀性的一种替代方法。然而，锌铁涂层在热成形过程中易发生液态熔化脆化。为了防止LME，必须在成形操作前将涂层完全转变为固溶体，避免锌液相与钢衬底接触。这项工作的目的是确定相变温度和临界冷却速度，以确定22MnB5锌铁涂层板材在比直接常规热成形工艺更高的加热速率时的工艺窗口。实验结果表明，当冷却速度为30℃/S时，获得了完全马氏体组织，所采用的双面镀锌层重量为80g/m(2)，在53℃/S~900℃加热，完全转变为23 S的Fe-α固溶体，与传统加热炉工艺所需的较长停留时间相比，这是一项工业上的进步。(C)2019年提交人。爱思唯尔出版公司(Elsevier B.V.)
In the last years, press-hardening steels have contributed to the automotive industry successfully to meet the increasing regulations for reducing fuel consumption and stringent greenhouse gas emissions while improving passenger safety by manufacturing lightweight car body parts. Zn-Fe coating is an alternative to prevent corrosion or even enhance the corrosion resistance in these steels. However, Zn-Fe coating is prone to liquid melting embrittlement (LME) during the hot forming process. To prevent LME, the coating must be fully transformed into a solid solution before the forming operation, avoiding the contact of the Zinc liquid phase with the steel substrate. This work aimed to determine the phase temperature transformations and critical cooling rate to define the process window for a 22MnB5 sheet with a Zn-Fe coating when submitted to a higher heating rate in comparison to the direct conventional hot forming process. The experimental results indicated that a fully martensitic microstructure is obtained with a cooling rate of 30 degrees C/s. The adopted two-side Zn coating weight of 80 g/m(2) heated at 53 degrees C/s to 900 degrees C is fully transformed into Fe-alpha solid solution in 23 s, which is an industrial gain compared to longer dwell times required in the conventional heating furnace processes. (C) 2019 The Authors. Published by Elsevier B.V.