Microstructural evolution of Mo?W?V alloyed hot-work die steel during high-temperature tempering
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摘要: 為適應熱沖壓技術的發展需求，開發了一種新型高熱導率高耐磨性能熱沖壓用模具鋼材料。采用掃描電鏡（SEM）、透射電鏡（TEM）等檢測手段對鉬鎢釩合金化新型模具鋼的高溫回火性能與組織特征進行了研究。闡明了新型熱沖壓模具鋼回火過程碳化物析出與演變規律。實驗結果表明：實驗用鉬鎢釩合金化模具鋼材料具有良好的回火二次硬化性能，在500～600 ℃溫度區間回火時，回火組織硬度上升；在600 ℃回火出現二次硬化峰值；當回火溫度超過600 ℃后，組織軟化程度明顯，回火硬度開始下降。實驗模具鋼在高溫回火過程中的硬度變化與其合金碳化物的偏聚、析出和聚集長大密切相關。當在560 ℃以下回火時，實驗鋼組織中未有合金碳化物析出；當回火溫度大于560 ℃時，回火組織中開始析出M2C型碳化物；當回火溫度高于600 ℃后開始析出MC型碳化物；當在620 ℃長時間回火后M2C型碳化物轉化為M6C型碳化物，此時實驗鋼硬度開始明顯下降；而當回火溫度高于660 ℃時，新型實驗鋼組織中主要為M6C和MC型合金碳化物。Abstract: Hot-work die steels are widely used to meet the requirements of industrial applications in which the steels must endure high temperature and mechanical loads, such as the hot stamping of very-high-strength steel. In the field of hot-stamping technology applications, the tool materials must have excellent high-temperature performance, such as the high-temperature stability of the microstructure. Research on hot-stamping die materials began somewhat late in China because high-quality die steel products had typically been imported. A new type of hot-stamping die steel with high thermal conductivity and high wear resistance was developed to meet the requirements of hot-stamping technology. In this study, we used scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to determine the high-temperature tempering performance and microstructural characteristics of this new Mo?W?V alloyed hot-work die steel. Based on the results, we derived the precipitation and evolvement rules of the carbides in the new type hot-stamping die steel during the tempering process, which indicate that the new Mo?W?V alloyed test steel has an excellent secondary hardening property. We find the hardness of the microstructure to increase after tempering at 500 ℃–600 ℃; however, at tempering temperatures above 600 °C, the matrix obviously softens and the hardness of the test-steel microstructure decreases. The hardness of the test die steel is strongly linked to the segregation, precipitation and growth of the alloy carbides in the matrix. No alloy carbide precipitation is observed at tempering temperatures below 560 ℃; however, M2C-type carbide precipitation is observed at tempering temperatures higher than 560 ℃. MC-type alloy carbide is observed in the test-steel matrix at tempering temperatures up to 600 ℃. At tempering temperatures above 620 ℃, the M2C-type alloy carbides transform into M6C-type alloy carbides and the hardness curve of the test steel sharply declines. The MC-type and M6C-type alloy carbides are the main carbides in the matrix of the new Mo?W?V alloyed hot-work die steel.
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Key words:
- die steel /
- heat treatment /
- alloy carbide /
- microstructure /
- transmission electron microscopy
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圖 2 不同熱處理后組織掃描電鏡照片。（a）淬火態；（b）560 ℃回火；（c）600 ℃回火；（d）620 ℃回火；（e）640 ℃回火；（f）700 ℃回火
Figure 2. SEM images of microstructure after heat treatment: (a) after quenching; (b) tempering at 560 ℃; (c) tempering at 600 ℃; (d) tempering at 620 ℃; (e) tempering at 640 ℃; (f) tempering at 700 ℃
圖 3 回火組織掃描電鏡照片。（a）600 ℃；（b）640 ℃；（c）700 ℃
Figure 3. SEM images of tempering microstructure: (a) 600 ℃; (b) 640 ℃; (c) 700 ℃
圖 4 520 ℃回火保溫60 h后的基體組織的透射電鏡照片。（a）明場；（b）暗場相和對應衍射斑點
Figure 4. TEM images of microstructure after tempering for 60 h at 520 ℃: (a) bright-field image; (b) dark-field image and diffraction patterns
圖 5 560 ℃回火保溫60 h后的基體組織的透射電鏡照片。（a）明場；（b）暗場像和對應的衍射斑點
Figure 5. TEM images of microstructure after tempering for 60 h at 560 ℃: (a) bright-field image; (b) dark-field image and diffraction patterns
圖 6 600 ℃回火保溫4 h后的基體組織的M2C型碳化物透射電鏡照片。（a）明場；（b）暗場像和對應的衍射斑點
Figure 6. TEM images of M2C carbides in microstructure after tempering for 4 h at 600 ℃: (a) bright-field image; (b) dark-field image and diffraction patterns
圖 7 600 ℃回火保溫4 h后的基體組織的MC型碳化物透射電鏡照片。（a）明場；（b）暗場像和對應的衍射斑點
Figure 7. TEM images of MC carbides in microstructure after tempering for 4 h at 600 ℃: (a) bright-field image; (b) dark-field image and diffraction patterns
圖 8 620 ℃回火保溫4 h后的基體組織中碳化物透射電鏡照片。（a）明場；（b）暗場像和對應的衍射斑點
Figure 8. TEM images of carbides in microstructure after tempering for 4 h at 620 ℃: (a) bright-field image; (b) dark-field image and diffraction patterns
圖 9 620 ℃回火保溫20 h后的基體組織的M6C型碳化物透射電鏡照片。（a）明場；（b）暗場像對應的衍射斑點
Figure 9. TEM images of M6C carbides in microstructure after tempering for 20 h at 620 ℃: (a) bright-field image; (b) dark-field image and diffraction patterns
圖 10 660 ℃回火保溫4 h后的基體組織的M6C型碳化物透射電鏡照片。（a）明場；（b）暗場像和對應的衍射斑點
Figure 10. TEM images of M6C carbides in microstructure of test steel after tempering for 4 h at 660 ℃: (a) bright-field image; (b) dark-field image and diffraction patterns
中文字幕在线观看表 1 實驗鋼成分（質量分數）
Table 1. Composition of the test steel
% C Si Mn Cr Mo W V P S Fe 0.48 0.10 0.08 0.13 2.99 1.70 0.86 0.01 0.02 Bal. 
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參考文獻
[1] Cui K. Present condition and developing direction of die steels in China. Mater Mech Eng, 2001, 25(1): 1 doi: 10.3969/j.issn.1000-3738.2001.01.003崔崑. 中國模具鋼現狀及發展(Ⅰ). 機械工程材料, 2001, 25(1):1 doi: 10.3969/j.issn.1000-3738.2001.01.003 [2] Mao M T, Guo H J, Sun X L, et al. Recent progress on primary carbides in AISI H13 hot work mold steel. Chin J Eng, 2018, 40(11): 1288毛明濤, 郭漢杰, 孫曉林, 等. H13熱作模具鋼中液析碳化物的研究進展. 工程科學學報, 2018, 40(11):1288 [3] Li S, Wu X C, Li X X, et al. High temperature performance of a Mo-W type hot work die steel of high thermal conductivity. Chin J Mater Res, 2017, 31(1): 32 doi: 10.11901/1005.3093.2016.037李爽, 吳曉春, 黎欣欣, 等. 鉬鎢系高導熱率熱作模具鋼高溫性能. 材料研究學報, 2017, 31(1):32 doi: 10.11901/1005.3093.2016.037 [4] Li S, Wu X C, Chen S H, et al. Wear resistance of H13 and a new hot-work die steel at high temperature. J Mater Eng Perform, 2016, 25(7): 2993 doi: 10.1007/s11665-016-2124-2 [5] Li S, Zhou L H, Wu X C, et al. The influence of thermal conductivity of die material on the efficiency of hot-stamping process. J Mater Eng Perform, 2016, 25(11): 4848 doi: 10.1007/s11665-016-2332-9 [6] Chen S H, Li S, Wu X C. High temperature friction and wear property of hot stamping tool steel SDCM. Tribology, 2016, 36(5): 538陳士浩, 李爽, 吳曉春. 熱沖壓模具鋼SDCM高溫摩擦磨損性能. 摩擦學學報, 2016, 36(5):538 [7] Chen Y W, Wu X C, Song W W, et al. Effect of carbide evolution on thermal-stability in Nb-microalloyed hot work steel. Trans Mater Heat Treat, 2010, 31(5): 75陳英偉, 吳曉春, 宋雯雯, 等. 含鈮熱作模具鋼中碳化物的演變對熱穩定性的影響. 材料熱處理學報, 2010, 31(5):75 [8] Liu Q D, Liu W Q, Wang Z M, et al. 3D atom probe characterazation of alloy carbides in tempering martenite Ⅰ. Nucleation. Acta Metall Sinica, 2009, 45(11): 1281劉慶冬, 劉文慶, 王澤民, 等. 回火馬氏體中合金碳化物的3D原子探針表征Ⅰ. 形核. 金屬學報, 2009, 45(11):1281 [9] Kaschnitz E, Hofer P, Funk W. Thermophysical properties of a hot-work tool-steel with high thermal conductivity. Int J Thermophys, 2013, 34(5): 843 doi: 10.1007/s10765-012-1162-8 [10] Chen J D, Mo W L, Wang P, et al. Effects of tempering temperature on the impact toughness of steel 42CrMo. Acta Metall Sinica, 2012, 48(10): 1186 doi: 10.3724/SP.J.1037.2012.00340陳俊丹, 莫文林, 王培, 等. 回火溫度對42CrMo鋼沖擊韌性的影響. 金屬學報, 2012, 48(10):1186 doi: 10.3724/SP.J.1037.2012.00340 [11] Li Z J, Xiao N M, Li D Z, et al. Influence of microstructure on impact toughness of G18CrMo2-6 steel during tempering. Acta Metall Sinica, 2014, 50(7): 777李振江, 肖納敏, 李殿中, 等. G18CrMo2-6鋼回火組織及沖擊韌性研究. 金屬學報, 2014, 50(7):777 [12] Min N, Shi N N, Shen Y L, et al. Internal friction investigation on thermal-stability of martensitic hot work steel. Trans Mater Heat Treat, 2012, 33(2): 96閔娜, 石楠楠, 沈赟靚, 等. 馬氏體熱作模具鋼熱穩定性的內耗研究. 材料熱處理學報, 2012, 33(2):96 [13] 朱春燕, 石楠楠, 左鵬鵬, 等. Mn 和 W 元素對 4Cr2Mo2W2V 模具鋼熱穩定性的影響. 材料熱處理學報, 2014, 35(增刊2):66)Zhu C Y, Shi N N, Zuo P P, et al. Effect of Mn and W on thermal stability of 4Cr2Mo2W2V die steel. Trans Mater Heat Treat, 2014, 35(增刊2): 66 [14] Medvedeva A, Bergstr?m J, Gunnarsson S, et al. High-temperature properties and microstructural stability of hot-work tool steels. Mater Sci Eng A, 2009, 523(1-2): 39 doi: 10.1016/j.msea.2009.06.010 [15] Michaud P, Delagnes D, Lamesle P, et al. The effect of the addition of alloying elements on carbide precipitation and mechanical properties in 5% chromium martensitic steels. Acta Mater, 2007, 55(14): 4877 doi: 10.1016/j.actamat.2007.05.004 [16] Chen Y, Chen Z Z, Dong H, et al. Adavance in research of tempering secondary hardening of alloy tool and die steel Fe-M-C quenched martensite. Special Steel, 2004, 25(2): 35 doi: 10.3969/j.issn.1003-8620.2004.02.012陳鷹, 陳再枝, 董瀚, 等. 合金工模具鋼Fe-M-C淬火馬氏體回火的二次硬化研究進展. 特殊鋼, 2004, 25(2):35 doi: 10.3969/j.issn.1003-8620.2004.02.012 [17] Liu Q D, Peng J C, Liu W Q, et al. 3D atom probe characterazation of alloy carbides in temperature martenite Ⅱ. Growth. Acta Metall Sinica, 2009, 45(11): 1288 doi: 10.3321/j.issn:0412-1961.2009.11.003劉慶冬, 彭劍超, 劉文慶, 等. 回火馬氏體中合金碳化物的3D原子探針表征Ⅱ. 長大. 金屬學報, 2009, 45(11):1288 doi: 10.3321/j.issn:0412-1961.2009.11.003 [18] Liu Q D, Chu Y L, Wang Z M, et al. 3D atom probe characterization of alloying elements partitioning in cementite of Nb-V microalloying steel. Acta Metall Sinica, 2008, 44(11): 1281 doi: 10.3321/j.issn:0412-1961.2008.11.001劉慶冬, 褚于良, 王澤民, 等. Nb-V微合金鋼中滲碳體周圍元素分布的三維原子探針表征. 金屬學報, 2008, 44(11):1281 doi: 10.3321/j.issn:0412-1961.2008.11.001 -
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