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SOLUTION TREATMENT EFFECTS IN COBALT-NICKEL secondary hardening STEEL

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Acta Metallurgica Sinica(English Letters) 1996年第6期9卷 613-618页

作者： P. Zhong B. Ling and B.Z. Gu(Beijing Institute of Aeronautical Materials, Beijing 100095, Beijing Inst of Aeronautical materials Beijing China

Effect of the austenitizing temperature on the microstructure,strength, and toughness of 16NiCo and 23NiCo alloys was studied. With increasing austenitizing temperature, the reductions in strength and hardness are probably caused by the coarsening of M_2C carbides. The use of higher austenitizing temperature resulted in improved impact toughness due to the dissolution of undissolved (Cr, Fe, Mo)_(23)C_6 *** the austenitizing temperature is increased to 1050℃ for 16NiCo and 23NiCo alloys impact toughness levels are reduced on average by 31 and 53 J/cm￣2 *** use of 1050℃ austenitizing temperatures resulted in intergranular fracture for 23NiCo alloy in 482℃ aged condition. It was suggested that this grain boundary embrittlement was the result of the formation of cementite particles during ageing.

关键词： secondary hardening ultrahigh strength steel austenitizing temPerature

secondary hardening OF BAINITE IN HIGH SPEED STEEL

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Acta Metallurgica Sinica(English Letters) 1990年第2期3卷 99-103页

作者： YU Xuejie Shanghai Iron and Steel Research Institute,Shanghai,China ZHOU Tianjian Anhui Institute of Technology,Hefei,China YU Xuejie Senior Engineer,Shanghai Iron and Steel Research Institute,1001 Taihe Road,Wusong,Shanghai 200940,China

The mechanical properties and structure of bainite and martensite after tempering m 6-5-4-2 high speed steel have been *** was found that the secondary hardening effect and resistance to heat softening as well as impact toughness are higher in the bainite than in the *** observations show that the(Fe,M)_3C precipitated in the martensite after tempering at temperature near the peak of hardness-tempering temperature ***, no(Fe,M)_3C but the dispersive MC and M_2C precipitated in the ferrite and austenite of bainite after tempering at the same *** indicates that the diffusion of alloy ele- ments forming carbide might exist during the process of bainite growing.

关键词： high speed steel bainite secondary hardening

ON THE STRENGTHENING MECHANISM OF HIGH Co-Ni ULTRAHIGH STRENGTH STEEL

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Acta Metallurgica Sinica(English Letters) 1996年第6期9卷 647-651页

作者： B. Ling P. Zhong B. W Zhong Z. Y Zhao and S.Q. Zhang(Beijing Institute of Aeronautical Materials, Beijing 100095,) Beijing Inst of Aeronautical Materials Beijing China

In this paper, the microstructure and strengthening mechanism of 23NiCo steel were studied by transmission electron microscopy and atom-probe field-ion microscopy. The results show that the peak strength obtained when the steel is tempered at 440455℃is due to the precipitation of coherent zones of fine *** peak in toughness attained at the absence of cementite and the formation of reverted and stable *** at higher temperatures resulted in loss of both strength and toughness. The drop of the strength of the steel tempered at high temperature is due to precipitation coarsening and loss of coherence with the matrix.

关键词： ultrahigh strength steel secondary hardening tempering

The evolution of carbides in the tempering process of semi-high speed steel cold rolls with nitrogen addition

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Baosteel Technical Research 2009年第2期3卷 42-45页

作者： WU Qiong SUN Dale YAO Lisong LIU Changsheng School of Materials ＆ Metallurgy Northeastern University Shenyang 110004 China Equipment Division Baosteel Research Institute Baoshan Iron ＆ Steel Co. Ltd. Shanghai 201900 China

This study analyzes the evolution of carbides in the tempering process of a newly developed semi-high speed steel cold forged roll with nitrogen addition using a transmission electron microscope （TEM） equipped with an energy dispersive X-ray （EDX）. The precipitation sequence of the carbides was identified in the entire tempering process and it can be expressed as M3C→M3C ＋ M （C, N）Ⅱ→M（ C, N）Ⅱ → M7C3Ⅱ ＋ M23 C6. The secondary hardening in the tempering process was mainly due to the dispersed precipitation of fine M（ C, N）n particles. The dissolution of M3 C tempered at high temperatures induced the precipitation and coarsening of M7 C31/ and M23 C6.

关键词： carbide evolution precipitation sequence secondary hardening characteristic EDX spectra