Hardening mechanisms and impact toughening of a high-strength steel containing low Ni and Cu additions
Hardening mechanisms and impact toughening of a high-strength steel containing low Ni and Cu additions
复制标题
低镍、铜添加量高强度钢的硬化机制和冲击韧化
DOI：
10.1016/j.actamat.2019.04.041
复制
发表时间：
2019-06-15
期刊：
影响因子：
9.4
通讯作者：
Liu, C. T.
中科院分区：
文献类型：
--
作者：
Kong, H. J.;Xu, C.;Liu, C. T.
在400-550摄氏度下的时效处理通常用于获得富Cu纳米团簇强化的高强度低合金（HSLA）钢的峰值强化。然而，这些温度落在危险的300-600摄氏度回火脆性范围内，导致冲击韧性差。另一方面，在高于脆化区的温度下时效可以提高冲击韧性，但以强度为代价。本文研究了低成本低碳（C约为0.08wt.%）可焊高强度低合金钢的强韧化机理，镍（Ni = 0.78重量%），和铜（Cu = 1.3重量%）被仔细调查过。结果表明，低碳NiCu低合金高强钢对时效温度不敏感，在640 ℃热处理温度下，通过多种强化机制，屈服强度和抗拉强度分别超过1000和1100 MPa，拉伸塑性大于10%（断面收缩率大于60%）。此外，良好的低温具有高YS（类似于900 MPa）和UTS（类似于1000 MPa）的高强度（类似于40 ℃）冲击性能（类似于200 J）可以通过在细晶粒尺寸（类似于2.5 gm）、中等尺寸（类似于14 nm）过时效富Cu沉淀物、回火马氏体和新鲜马氏体（或碳化物）之间寻求强度平衡来获得。此外，可通过在640 ℃下延长时效来获得可用于钢制造的相对较低的YS（类似于800 MPa）和UTS（类似于900 MPa）。此外，本研究亦以位错理论为基础，探讨了位错与析出物的交互作用。(C)2019 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
Aging treatments at 400-550 degrees C are commonly used to attain a peak strengthening for the Cu-rich nanocluster-strengthened high-strength low-alloy (HSLA) steels. However, these temperatures fall within the dangerous 300-600 degrees C temper-embrittlement regime, leading to poor impact toughness. On the other hand, aging at temperatures above the embrittlement regime can improve the impact toughness but at a great expense of strength. In this work, the strengthening mechanisms as well as the toughening of a low cost weldable HSLA steel with a low content of carbon (C similar to 0.08 wt.%), nickel (Ni = 0.78 wt.%), and copper (Cu = 1.3 wt.%) were carefully investigated. Our findings show that the low-C-Ni-Cu HSLA steel is insensitive to the aging temperatures and can achieve a yield strength (YS) and ultimate tensile strength (UTS) over 1000 and 1100 MPa, respectively, with tensile ductility >10% (reduction of area >60%) at a heat-treat temperature of 640 degrees C through multiple strengthening mechanisms. Besides, a good low-temperature (similar to 40 degrees C) impact performance(similar to 200 J) with high YS (similar to 900 MPa) and UTS (similar to 1000 MPa) can be obtained by seeking a strength balance among the fine grain size (similar to 2.5 gm), medium-sized (similar to 14 nm) overaged Cu-rich precipitates, tempered martensite, and fresh martensite (or carbides). Moreover, a relatively lower YS (similar to 800 MPa) and UTS (similar to 900 MPa) useful for steel manufacturing can be attained by a prolonged aging at 640 degrees C. In addition, the dislocation-precipitate interactions were also explored based on the dislocation theories in this study. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.