Nb-Ti微合金化熱沖壓成形用鋼的微觀組織與力學性能

聞玉輝; 朱國明; 郝亮; 戴思雨; 康永林

doi:10.13374/j.issn2095-9389.2017.06.007

Nb-Ti微合金化熱沖壓成形用鋼的微觀組織與力學性能

doi: 10.13374/j.issn2095-9389.2017.06.007

1) 北京科技大學材料科學與工程學院, 北京 100083
2) 北京科技大學新金屬材料國家重點實驗室, 北京 100083

基金項目:

國家自然科學基金資助項目(U1460101)

高等學校博士學科點專項科研基金資助項目(20120006120002)

詳細信息

中圖分類號: TG142.1
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出版歷程
- 收稿日期: 2016-06-20

Microstructure and mechanical properties of Nb-Ti micro-alloy hot stamping steels

1) School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083, China
2) State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083, China

摘要

摘要: 利用掃描電鏡(SEM)、透射電鏡(TEM)對Nb-Ti微合金化熱成形鋼的微觀組織進行觀察,采用Kahn撕裂試驗對其韌性和撕裂性能進行了研究,并利用Thermo-Calc熱力學軟件對其析出行為和析出粒子成分進行分析計算.結果表明,含碳質量分數0.13%的熱成形鋼在Nb-Ti微合金化后的組織為馬氏體,和傳統熱成形鋼(22MnB5)相比其奧氏體晶粒、板條塊和板條束都得到細化,并且其抗拉強度達到1500 MPa以上,撕裂強度和單位面積裂紋擴展能分別達到1878 MPa、436 kN·m-1.在950℃奧氏體化時,Nb-Ti合金元素幾乎全部以析出粒子形式存在,能有效阻止奧氏體晶粒長大.另外在基體中主要存在兩種析出物,一種是尺寸在100~200 nm的Ti (C,N);另一種是納米級別的鈦鈮復合碳氮化物,能有效強化基體,提高強度.
- 熱成形鋼 /
- 板條馬氏體 /
- 撕裂強度 /
- 析出粒子
Abstract: The microstructure of Nb-Ti micro-alloy hot stamping steels was observed and investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The toughness and tear properties were investigated by Kahn tear test. The thermodynamic software Thermo-Calc was used to calculate and analyze the behavior and composition of precipitates. The results show that Nb-Ti micro-alloy hot stamping steels with mass fraction 0.13% C are composed of martensite. Compared with traditional hot stamping steel (22MnB5), the Nb-Ti micro-alloy steel has finer prior austenite grains, martensite packets, and martensite laths. The tensile strength is more than 1500 MPa, tear strength is 1878 MPa, and the unit propagation energy is 436 kN·m-1. Nearly all Nb——Ti elements exist as precipitates during austenization at 950℃ and they can hinder the growth of austenite grains effectively. Two types of precipitates of different sizes are dispersed in the martensite matrix. The sizes of Ti(C, N) precipitates range from 100 nm to 200 nm, and their quantity is low. The nanometer-sized precipitates are carbides or nitrides of Ti and Nb, which can strengthen the martensite matrix and improve the intensity.
- hot stamping steels /
- martensite laths /
- tear strength /
- precipitates

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參考文獻(9)

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