Influence of heat treatment process on microstructure and properties of SDP80C steel

doi:10.13251/j.issn.0254-6051.2025.02.038

Abstract

Abstract: Austenite continuous cooling transformation curve of pre-hardened die casting steel SDP80C was measured by using a thermal dilatometer, and the microstructure and mechanical properties under different aging processes were studied. The results show that the martensitic transformation starting temperature (Ms) of the SDP80C steel is 320 ℃, the austenite transformation starting temperature (Ac₁) is 695 ℃, and the austenite transformation ending temperature (Ac₃) is 841 ℃. Within the aging temperature range of 525-600 ℃, the increase of aging temperature promotes the formation and growth of NiAl phase and Cu-rich phase, and the martensite recovers. As a result, the hardness of the SDP80C steel gradually decreases while the impact property improves. After aging at 525 ℃ for 2 h, the SDP80C steel reaches the maximum hardness of 44.9 HRC and the impact absorbed energy is about 123 J, which is attribute to the precipitation strengthening of nano-scale NiAl phase and Cu-rich phase.

Key words: die casting mold steel SDP80C, aging process, hardness, impact property, NiAl phase

CLC Number:

TG178

Chen Shengnan, Peng Ruizhi, Wu Xiaochun. Influence of heat treatment process on microstructure and properties of SDP80C steel[J]. Heat Treatment of Metals, 2025, 50(2): 241-246.

References

[1] Li Jun, Zhang Xu, Bu Hengyong, et al. Effects of deep cryogenic treatment on the microstructure evolution, mechanical and thermal fatigue properties of H13 hot work die steel[J]. Journal of Materials Research and Technology, 2023, 27: 8100-8118.
[2] Zhang H, Qiu F, Yang H Y, et al. Microstructure manipulation mechanism and mechanical properties improvement of H13 steel via trace nano-(TiC+TiB₂) particles[J]. Materials Characterization, 2022, 188: 111924.
[3] 李玲, 蔡著文, 黄苏起, 等. 预处理工艺对Cr3型压铸模具钢组织性能的影响[J]. 模具工业, 2019, 45(12): 47-51.
Li Ling, Cai Zhuwen, Huang Suqi, et al. Effect of pretreatment process on microstructure and properties of Cr3 die casting die steel[J]. Die and Mould Industry 2019, 45(12): 47-51.
[4] Shen Qin, Huang Daozhu, Liu Wenqing, et al. Effect of Cu content on the precipitation behavior of Cu-rich and NiAl phases in steel[J]. Materials Characterization, 2022, 187: 111849.
[5] Bailey G W, Dimlich R V W, Alexander K B, et al. Analytical TEM study of nanophase precipitation in NiAl alloys[J]. Microscopy and Microanalysis, 1997, 3(S2): 1007-1008.
[6] Xu S S, Li J P, Cui Y, et al. Mechanical properties and deformation mechanisms of a novel austenite-martensite dual phase steel[J]. International Journal of Plasticity, 2020, 128: 102677.
[7] Vo Q N, Liebscher H C, Rawlings J S M, et al. Creep properties and microstructure of a precipitation-strengthened ferritic Fe-Al-Ni-Cr alloy[J]. Acta Materialia, 2014, 71: 89-99.
[8] Jiao Z B, Luan J H, Miller M K, et al. Precipitation mechanism and mechanical properties of an ultra-high strength steel hardened by nanoscale NiAl and Cu particles[J]. Acta Materialia, 2015, 97: 58-67.
[9] Jiao Z B, Luan J H, Miller M K, et al. Effects of Mn partitioning on nanoscale precipitation and mechanical properties of ferritic steels strengthened by NiAl nanoparticles[J]. Acta Materialia, 2015, 84: 283-291.
[10] Zhou B C, Yang T, Zhou G, et al. Mechanisms for suppressing discontinuous precipitation and improving mechanical properties of NiAl-strengthened steels through nanoscale Cu partitioning[J]. Acta Materialia, 2021, 205: 116561.
[11] Liu Q D, Song H, Zhang J, et al. Strengthening of Ni-Mn-Cu-Al-Co steel by nanoscale Cu and β-NiAl co-precipitated couples[J]. Materials Characterization, 2021, 171: 110754.
[12] 郭建亭. 金属间化合物NiAl的研究进展[J]. 中南大学学报(自然科学版), 2007, 38(6): 1013-1027.
Guo Jianting. Research progress of intermetallic NiAl alloys[J]. Journal of Central South University(Science and Technology), 2007, 38(6): 1013-1027.
[13] Shen Q, Xiong X, Li T, et al. Effects of co-addition of Ni and Al on precipitation evolution and mechanical properties of Fe-Cu alloy[J]. Materials Science and Engineering A, 2018, 723: 279-286.
[14] 冷文秀, 田文怀. Ni-Al-Fe中NiAl/Fe互为基体/析出相的组织特征[J]. 稀有金属, 2009, 33(2): 185-190.
Leng Wenxiu, Tian Wenhuai. Precipitation characteristics by/in NiAl/Fe taken as matrix/precipitate in Ni-Al-Fe system[J]. Chinese Journal of Rare Metals, 2009, 33(2): 185-190.
[15] Hellman C O, Rivage du J B, Seidman N D. Efficient sampling for three-dimensional atom probe microscopy data[J]. Ultramicroscopy, 2003, 95: 199-205.
[16] Dmitrieva O, Ponge D, Inden G, et al. Chemical gradients across phase boundaries between martensite and austenite in steel studied by atom probe tomography and simulation[J]. Acta Materialia, 2011, 59: 364-374.