Strengthing and toughening mechanism of weld metal of 690 MPa grade high strength steel
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摘要:
制备了两个不同类型屈服强度为690 MPa级焊缝金属，开展了微观组织分析和力学性能测试，研究了焊缝金属的强韧化机理. 结果表明，传统690MPa级焊缝金属镍当量(Nieq)较小，枝晶间区域合金元素偏析不明显，焊缝金属形成以粗大的粒状贝氏体(grain bainite, GB)为主的相对均一组织，由于粗大的GB对裂纹扩展的阻力较小，其低温韧性较差. 通过提高Nieq的方法制备了新型690 MPa级焊缝金属，其Nieq较大，Mn，Ni在枝晶间区域显著偏析导致枝晶间过冷奥氏体的稳定性大于枝晶干，形成了枝晶干为针状铁素体(acicular ferrite, AF)，枝晶间为板条马氏体(lath martensite，LM)的复相组织. 在复相组织中AF为主要的韧化相，LM为主要的强化相，焊缝金属的屈服强度为738 MPa，−50 ℃冲击吸收能量为122 J，实现了良好的强韧性匹配.
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关键词:
- 690 MPa级高强钢 /
- 焊缝金属 /
- 复相组织 /
- 合金偏析 /
- 强韧化机理
Abstract:Two different types of weld metals with yield strength of 690 MPa were prepared. The microstructure analysis and mechanical properties test were carried out and the mechanism of strengthen-tougheness was revealed. The results showed that the nickel equivalent ( Nieq ) of the traditional 690 MPa grade weld metal was small, and the segregation of alloy elements in the interdendritic region could be negligible. he weld metal formed a relatively uniform structure dominated by coarse granular bainite (GB). Because the coarse GB had little resistance to crack propagation, its low temperature toughness was poor. A new type of 690MPa grade weld metal was prepared by increasing Nieq. Due to the significant segregation of Mn and Ni in the inter-dendritic region, the stability of undercooled austenite in the interdendritic region was greater than that in the dendrite region, therefore the weld metal formed a complex phase structure with acicular ferrite (AF) in the dendrite and lath martensite (LM) in the interdendritic region. In this composite structure, AF was the main toughening phase and LM was the main strengthening phase. The yield strength of the weld metal was 738 MPa, and the impact absorption energy at −50 ℃ was 122 J, which achieved a good matching of strength and toughness.
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图 2 TEM下焊缝金属的微观组织
Figure 2. Microstructure of weld metals under TEM. (a) TM of HT-01; (b) bright field phase of interdendritic retained austenite of HT-02; (c) dark field phase of interdendritic retained austenite of HT-02
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图 3 焊缝金属−50 ℃夏比冲击断口形貌
Figure 3. Charpy impact fracture morphology of weld metals at −50 ℃. (a) HT-01; (b)fiber zone of HT-01; (c)radiation zone of HT-01; (d) HT-02; (e) fiber zone of HT-02; (f) Cleavage fracture plane of HT-02
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图 4 焊缝金属−50 ℃夏比冲击断口一次裂纹
Figure 4. Charpy impact main crack of weld metals at −50 ℃. (a) HT-01; (b)Local amplification of Fig. 4(a); (c) HT-02; (d)Local amplification of Fig. 4(c)
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图 5 焊缝金属彩色金相组织
Figure 5. Color Metallographic structure of weld metals. (a) HT-01; (b) HT-02
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图 6 焊缝金属的强韧化机制
Figure 6. Strengthening and toughening mechanism of weld metals. (a) traditional weld metal; (b) new weld metal
表 1 焊缝金属化学成分(质量分数，%)
Table 1 Chemical composition of weld metals
焊条编号 C Si Cr + Mo Mn Ni Nieq HT-01 0.043 0.327 0.885 1.60 2.42 4.51 HT-02 0.037 0.302 0.312 0.88 4.88 6.43 
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表 2 焊缝金属力学性能
Table 2 Mechanical properties of weld metals
焊条编号 屈服强度ReL/MPa 抗拉强度Rm/MPa 断后伸长率A(%) 断面收缩率Z(%) −50 ℃冲击吸收能量AkV/J HT-01 736 797 20.0 66 59 HT-02 738 805 20.5 68 122
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[1] JOYDEEP R, PRITAM D. Effect of B2O3 enrichment on microstructural inhomogeneity of high strength steel weldments[J]. China Welding, 2024, 33(3): 25 − 32.
[2] WANG X L, SU W J, XIE Z J, et al. Microstructure evolution of heat-affected zone in submerged arc welding and laser hybrid welding of 690MPa high strength steel and its relationship with ductile–brittle transition temperature[J]. Acta Metallurgica Sinica (English Letters), 2023, 36(4): 623 − 636. doi: 10.1007/s40195-022-01498-0
[3] DAMIR A, CHU D, BRIAN B. Response and strength of intermediately stiffened cold-formed Steel lipped channel columns formed from 100 ksi(690MPa) Steel[C]//Annual Stability Conference Structural Stability Research CouncilApril 11-14, 2023, Charlotte, North Carolina. Chicago: AISC, 2023.
[4] 孟满丁, 魏金山, 安同邦, 等. Si元素对800 MPa级HSLA钢焊材熔敷金属组织及韧性的影响[J]. 焊接学报, 2024, 45(4): 93 − 100. doi: 10.12073/j.hjxb.20230425002 MENG Manding, WEI Jinshan, AN Tongbang, et al. Effects of Si content on microstructure and toughness of the 800 MPa grade high-strength low-alloy deposited metals[J]. Transactions of the China Welding Institution, 2024, 45(4): 93 − 100. doi: 10.12073/j.hjxb.20230425002
[5] 王伟, 何亮, 何磊. 船用高强钢焊接材料合金系研究现状[J]. 材料开发与应用, 2020, 35(6): 79 − 83. WANG Wei, HE Liang, HE Lei. Review on welding material alloy systems of high strength steels for ships[J]. Development and Application of materials, 2020, 35(6): 79 − 83.
[6] 汤忖江, 安同邦, 彭云, 等. 焊接热输入对690MPa级HSLA钢焊缝金属组织与力学性能的影响[J]. 焊接学报, 2024, 45(9): 110 − 119. doi: 10.12073/j.hjxb.20230501001 TANG Cunjiang, AN Tongbang, PENG Yun, et al. Effect of heat input on microstructure and mechanical properties of weld metal of 690 MPa grade HSLA steel[J]. Transactions of the China Welding Institution, 2024, 45(9): 110 − 119. doi: 10.12073/j.hjxb.20230501001
[7] QIU R P, FENG X. Effect of aluminium element on microstructure and properties of weld metal of 960MPa steel[J]. China Welding, 2020, 29(4): 48 − 53.
[8] 毛高军. Ni对低碳贝氏体焊缝金属组织和强韧性的影响及相变机理研究[D]. 兰州: 兰州理工大学, 2018. MAO Gaojun. Effect of nickel on microstructure evolution and strength-toughnessproperty development and bainite transformation mechanism in low-carbon bainitic weld metals[D]. Lanzhou: Lanzhou University of Technology, 2018.
[9] ZHOU Y L, JIA T, ZHANG X J, et al. Microstructure and toughness of the CGHAZ of an offshore platform steel[J]. Journal of Materials Processing Technology, 2015, 219: 314 − 320. doi: 10.1016/j.jmatprotec.2014.12.017
[10] LAN L Y, QIU C L, ZHAO D W, et al. Microstructural characteristics and toughness of the simulated coarse grained heat affected zone of high strength low carbon bainitic steel[J]. Materials Science & Engineering A, 2011, 529: 192 − 200.
[11] LEPERA F S. Improved etching technique to emphasize martensite and bainite in high-strength dual-phase steel[J]. Journal of Metals, 1980, 32(3): 38 − 39.
[12] DE A K, SPEER J G, MATLOCK D K. Color tint-teching for multiphase steels[J]. Advanced Material & Processes, 2003, 161(2): 27 − 30.
[13] YU C Y, LIU Q, CAI Z P, et al. Effect of solidification segregation on microstructure and mechanical properties of a Ni-Cr-Mo-V steel weld metal[J]. Metallurgical and Materials Transactions A, 2022, 53(4): 1394 − 1406. doi: 10.1007/s11661-022-06600-w
[14] SUN J, LU S P. Influence of inter-dendritic segregation on the precipitation behaviour and mechanical properties in a vanadium-containing Fe-Cr-Ni-Mo weld metal[J]. Scripta Materialia, 2020, 186: 174 − 179. doi: 10.1016/j.scriptamat.2020.05.021
[15] 孙健. Fe-Cr-Ni-Mo系熔敷金属组织与性能研究[D]. 合肥: 中国科学技术大学, 2020. SUN Jian. Research on microstructure and properties of Fe-Cr-Ni-Mo deposited Metal[D]. Heifei: University of Science and Technology, 2020.
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