Microstructure and Mechanical Properties of High Strength Container Steel with Cu, Ni, Al, and RE AITranslate

［1］（王小龙，王毛球，孟彬，时捷，徐乐，孙挺. 回火工艺对Cr-Ni-Mo-V高强钢组织和力学性能的影响 ［J］. 金属热处理，2017，42（12）：6.）

X L Wang，M Q Wang，B Meng，J Shi，L Xu，T Sun. Effect of tempering process on microstructure and mechanical properties of Cr-Ni-Mo-V high strength steel ［J］. Heat Treatment of Metals，2017，42（12）：6.

［2］（庞庆海，郎庆斌，马窦琴，郭亚非，林乙丑. 2.25Cr1Mo0.25V钢连续冷却过程的相变行为 ［J］. 金属热处理，2019，44（2）：5.）

Q H Pang，Q B Lang，D Q Ma，Y F Guo，Y C Lin. 2.25Cr1Mo0.25V steel phase change behavior during continuous cooling ［J］. Heat Treatment of Metals，2019，44（2）：5.

［3］（黄有华，艾永平. Ⅱ型30CrMnSiA钢回火脆性研究 ［J］. 锻压技术，2024，49（12）：162.）

Y H Huang，Y P Ai. Study on temper brittleness for 30CrMnSiA steel of type II ［J］. Forging & Stamping Technology，2024，49（12）：162.

［4］Fu W，Li C N，Di X J，Fu K J，Gao H S，Fang C，Lou S Y，Wang D P. Refinement mechanism of nanoscale Cu-rich precipitates by Mo addition and its effect on strength-toughness of Cu-bearing low carbon high strength steel ［J］. Materials Science and Engineering：A，2022，849：143469.

［5］Kolli R P，Seidman D N. The temporal evolution of the decomposition of a concentrated multicomponent Fe-Cu-based steel ［J］. Acta Materialia，2008，56（ 9）：2073.

［6］Jiao Z B，Luan J H，Zhang Z W，Miller M K，Liu C T. High-strength steels hardened mainly by nanoscale NiAl precipitates ［J］. Scripta Materialia，2014，87（4）：45.

［7］（杜瑜宾，胡小锋，张守清，宋元元，姜海昌，戎利建. 含1.4%Cu的HSLA钢的组织和力学性能 ［J］. 金属学报，2020，56（10）：12.）

Y B Du，X F Hu，S Q Zhang，Y Y Song，H C Jiang，L J Rong. Microstructure and mechanical properties of HSLA steel containing 1.4%Cu ［J］. Acta Metallurgica Sinica，2020，56（10）：12.

［8］Xi X H，Wang J L，Chen L Q，Wang Z D. Tailoring mechanical properties of a low carbon Cu-containing structural steel by two-step intercritical heat treatment ［J］. Metals and Materials International，2019，25：1477.

［9］（解辉，王伟. 低合金铁素体钢中纳米富Cu相复杂晶体结构的表征 ［J］. 稀有金属，2018，42（3）：325.）

H Xie，W Wang. Characterization of complex crystal structures of nano-rich Cu-phase in low-alloy ferritic steels ［J］. Chinese Journal of Rare Metals，2018，42（3）：325.

［10］（张正延，柴锋，甘斌，杨洋，罗小兵，陈刚，杨才福. 轧后冷速对调质态含Cu高强钢组织性能的影响 ［J］. 连铸，2019，44（3）：5.）

Z Y Zhang，F Chai，B Gan，Y Yang，X B Luo，G Chen，C F Yang. Effect of cooling rate after rolling on microstructure and properties of quenched Cu containing high strength steel ［J］. Continuous Casting，2019，44（3）：5.

［11］Jiao Z B，Luan J H，Miller M K，Yu C Y，Liu C T. Group precipitation and age hardening of nanostructured Fe-based alloys with ultra-high strengths ［J］. Scientific Reports，2016，6：21364.

［12］（冷文秀，田文怀. Ni-Al-Fe钟NiAl/Fe互为基体/析出相的组织特征 ［J］. 稀有金属，2009，33（2）：185.）

W X Leng，W H Tian. Microstructure characteristics of Ni-Al-Fe clock NiAl/Fe as matrix/precipitated phase ［J］. Chinese Journal of Rare Metals，2009，33（2）：185.

［13］Gao X Y，Wang H Y，Xing L，Ma C N，Li Y M，Sha G，Ren H P. The synergistic effects of ultrafine grains and nano-size Cu-rich precipitates on the mechanical properties of DP steels ［J］. Materials Science & Engineering，A. Structural Materials：Properties，Misrostructure and Processing，2021（805-）：805.

［14］Kong H J，Xu C，Bu C C，Da C，Luan J H，Chen G，Liu C T. Hardening mechanisms and impact toughening of a high-strength steel containing low Ni and Cu additions ［J］. Acta Materialia，2019，172：150.

［15］Hou W，Liu Q D，Gu J F. Improved impact toughness by multi-step heat treatment in a 1400 MPa low carbon precipitation-strengthened steel ［J］. Materials Science and Engineering：A，2020，797：140077.

［16］Jain D，Isheim D，Hunter A H，Seidman D. Multicomponent high-strength low-alloy steel precipitation-strengthened by Sub-nanometric Cu precipitates and M2C carbides ［J］. Metallurgical and Materials Transactions A，2016，47（8）：1.

［17］Kapoor M，Isheim D，Vaynman S，Fine M E，Chung Y W. Effects of increased alloying element content on NiAl-type precipitate formation，loading rate sensitivity，and ductility of Cu-and NiAl-precipitation-strengthened ferritic steels ［J］. Acta Materialia，2016，104：166.

［18］Fu W，Li C N，Di X J，Fu K J，Gao H S，Fang C，Lou S Y，Wang D P. Improvement of Cu-rich precipitation strengthening for high-strength low carbon steel strengthened via Ti-microalloying ［J］. Materials Letters，2022，316：132031.

［19］Zhou B C，Yang T，Zhou G，Wang H，Luan J H，Jiao Z B. Mechanisms for suppressing discontinuous precipitation and improving mechanical properties of NiAl-strengthened steels through nanoscale Cu partitioning ［J］. Acta Materialia，2021: 205.

［20］Liu S，Tan H，Guo H，Shang C，Misra R D K. The determining role of aluminum on copper precipitation and mechanical properties in Cu-Ni-bearing low alloy steel ［J］. Materials Science & Engineering A，2016，676（oct.31）：510.

［21］Shen Q，Huang D，Liu W，Li F，Lu Q. Effect of Cu content on the precipitation behavior of Cu-rich and NiAl phases in steel ［J］. Materials Characterization，2022，187：111849.

［22］Jiao Z B，Luan J H，Miller M K，Yu C Y，Liu C T. Precipitation mechanism and mechanical properties of an ultra-high strength steel hardened by nanoscale NiAl and Cu particles ［J］. Acta Materialia，2015，97：58.

［23］Huang D，Yan J，Zuo X. Co-precipitation kinetics，microstructural evolution and interfacial segregation in multicomponent nano-precipitated steels ［J］. Materials Characterization，2019，155：109786.

［24］Jiao Z B，Luan J H，Zhang Z W，Miller M K，Ma W B，Liu C T. Synergistic effects of Cu and Ni on nanoscale precipitation and mechanical properties of high-strength steels ［J］. Acta Materialia，2013，61（16）：5996.

［25］（王奕，李长荣，熊星强，宁州韶. 稀土镧对SWRS82B钢中氧化铝夹杂物的影响 ［J］. 稀有金属，2022，46（9）：1199.）

Y Wang，C R Li，X Q Xiong，Z S Ning. Alumina inclusions in SWRS82B steel with rare earth lanthanum ［J］. Chinese Journal of Rare Metals，2022，46（9）：1199.

［26］（程天一，Canter B，Mclean M，Flower H M. 富Ni的NiAl室温延性和韧性的改善 ［J］. 金属学报，1993，29（3）：A121.）

T Y Cheng，B Canter，M Mclean，H M Flower. Improvement of ductility and toughness of Ni-rich NiAl at room temperature ［J］. Acta Metallurgica Sinica，1993，29（3）：A121.

［27］（沈琴. 钢中富Cu相和NiAl相复合析出机制的研究 ［D］. 上海：上海大学，2018. 1.）

Q Shen. Study on the Composite Precipitation Mechanism of Rich Cu Phase and NiAl Phase in Steel ［D］. Shanghai：Shanghai University，2018. 1.

［28］Hofinger M，Turk C，Ognianov M，Leitner H，Schnitzer R. Precipitation reactions in a Cu-Ni-Al medium carbon alloyed dual hardening steel ［J］. Materials Characterization，2020，160：110126.

［29］（高志国. 镧对1.5 GPa超高强度钢淬透性的影响 ［J］. 材料热处理学报，2020，41（11）：7.）

Z G Gao. Effect of lanthanum on hardenability of 1.5 GPa ultra-high strength steel ［J］. Transactions of Materials and Heat Treatment，2020，41（11）：7.

［30］Gao X Y，Wang H Y，Li C L，Ren H P，Liu Z C. First-principles study of the effect of lanthanum on the Cu diffusion mechanism in bcc-Fe ［J］. Acta Physica Sinica-Chinese Edition-，2014，63（24）：248101.

［31］You Y，Yan M F. Behaviors and interactions of La atmo with other foreign subtitutional atmos （Al，Si，Ti，V，Cr，Mn，Co，Ni，Cu，Nb or Mo） in iron based solid solution from first principles ［J］. Computtational Mateerials Science，2013，73：120.

Basic Information:

DOI：10.13373/j.cnki.cjrm.XY24060013

Chinese Library Classification Number:TG142.1

Citation Information:

With the large-scale development of pressure vessel structures and the gradual improvement of pressure capacity requirements，higher requirements are put forward for the comprehensive mechanical properties of raw materials，so it is necessary to develop new pressure vessel steel with higher strength. How to break the refutation that strong plasticity cannot be balanced，and how to improve the strength of steel materials without significantly reducing plasticity，has been a research hotspot for material scholars for a long time. It was found that by adding different alloying elements to the iron-based alloy and precipitating nano-scale precipitates in the iron-based alloy after solid solution-aging heat treatment，the strength of the iron-based alloy can be significantly improved，while maintaining good plasticity，which brings new inspiration to the material field. In order to study how to improve the strength level of the high-strength container steel without significantly reducing its plasticity，Cu，Ni，Al and rare earth elements （RE）were added to the high-strength container steel individually or in combination，held at 900 ℃ for 30 min，water quenched to room temperature，and then held at 550 ℃ for different times，air cooled to room temperature，isothermal aging heat treatment was carried out namely. Optical microscopy （OM）and field emission scanning electron microscopy （SEM）were used to characterize the microstructure of the test steel after quenching and aging. The evolution of the microstructure during isothermal aging at 550 ℃ was studied. The fine structure and precipitated phase morphology of the test steel after aging were characterized by transmission electron microscopy （TEM）. The evolution of mechanical properties of the test steel during isothermal aging at 550 ℃ was analyzed by Vickers hardness test and tensile test，and the macromorphology and micromorphology of tensile fracture were characterized by SEM. OM and SEM results show that the microstructures of the test steel were lath martensite after quenching，and the microstructures of the test steel were sautensite after aging heat treatment. Compared with base steel，the microstructure of the test steel with different alloying elements had different degrees of refinement，the microstructures of Cu steel and NiAl steel were obviously refined，and the microstructure of NiAl steel was more significant，because Cu and Ni had the effect of refining grains，The microstructure size of Cu-NiAl steel with Cu，Ni and Al was between that of Cu steel and NiAl steel，and the microstructure of Cu-NiAl-RE steel was further refined after RE was added，indicating that RE played a role in refining grain. TEM results of the test steel showed that there were a large number of dislocations entangled on the test steel lath，nano-scale rich Cu phase and NiAl phase precipitated on the matrix，RE reduced the width of the lath，but the type of precipitated phase was not changed. The test steel Vickers hardness results showed that during the isothermal aging process of 550 ℃，the hardness of the base steel showed a decreasing trend with the extension of the aging time，which was because the microstructure recovery occurred during the aging process，and the hardness of Cu steel showed an evolution law of first decreasing，then increasing and then decreasing. The hardness of NiAl steel，Cu-NiAl steel and Cu-NiAl-RE steel increased first and then decreased，which indicated that NiAl steel，Cu-NiAl steel and Cu-NiAl-RE steel were precipitation hardening during the isothermal aging process at 550 ℃. The tensile test results of the test steel showed that the strength at the aging peak of the test steel was increased to different degrees，and the yield strength and tensile strength of Cu steel were increased by 136.0 MPa and 113.2 MPa，respectively，which was caused by the precipitation of nano-Cu-rich phase on the matrix. The strength of NiAl steel changed weakly，which was related to the quantity density and size of NiAl phase precipitated in the matrix. The strength of Cu-NiAl steel increased significantly，the yield strength and tensile strength increased to 1271.0 MPa and 1322.0 MPa，respectively，and the elongation and section shrinkage decreased slightly to 18.2% and 58.3%，respectively. The strong plastic matching was good，which was caused by the precipitation of nano-Cu-NiAl co-precipitated phase in the matrix. The strength of Cu-NiAl-RE steel changed little after RE was added further. Plastic deformation is produced in the test steel during the tensile test. The macro fracture of the test steel was cup-cone with certain necking，and the shear lip was obvious in base steel and NiAl steel. No shear lip was observed in Cu steel，Cu-NiAl steel and Cu-NiAl-RE steel with higher strength. The tensile fracture microstructure showed both large and small dimples，which belonged to the typical ductile fracture mode of microporous aggregation. The effects of Cu，Ni，Al，and RE on the distribution，size and quantity density of nanoprecipitated phases were characterized and analyzed by three-dimensional atomic probe technology （APT）. The work was in progress，and the research results would be discussed in subsequent reports.