| RESEARCH PAPER |
|
|
|
|
|
| Cooling Behavior of Heat Treated Carburizing Steel 23CrNi3Mo with Proper Hardness Gradient and Microstructure Distribution |
| JIANG Bo1, DAI Guangyong2, YAN Yongming1, LIU Guanglei2, WANG Zhilin2,
WANG Guocun2, LIU Yazheng1
|
1 School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083;
2 Xining Special Steel Co. Ltd, Xining 810005 |
|
|
|
|
Abstract The continuous cooling transformation and isothermal transformation were investigated by thermal simulation machine Gleeble-1500, optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM). Based on the investigation, a new heat treatment cooling process was designed. Results show that the microstructures at the surface, the transition zone and the matrix of the steel after carburizing at the cooling rates of 0.05 ℃/s and 0.1 ℃/s are high carbon martensite, a mixed microstructure of lower bainite and high carbon martensite and lower bainite, respectively. The network carbide was formed along the boundary in the microstructure at the surface when the carburizing steel was cooled from the quenching temperature with a lower cooling rate from 0.05 ℃/s to 3 ℃/s. The temperature of bainite transformation of steel without carburizing ranges from 375 ℃ to 450 ℃. The new heat treatment cooling process was set as follow: the carburizing steel was cooled from 880 ℃ with a fast cooling rate of 5 ℃/s to the bainite transformation zone, and put into the salt bath furnace soaking for 5-10 minutes at 450 ℃; after that, the steel was slowly cooled at the cooling rate lower than 0.1 ℃/s. Microstructural examination indicates that the depth of carburizing case of the specimen after the new process is 1.4 mm, which is nearly the same with the drill bit from Atlas abroad (1.2 mm). The hardness distribution of the specimen after the new process is smoother. The obtained microstructures at the surface, the transition zone and the matrix of the specimen after the new process and the drill bit from Atlas abroad are both high carbon martensite, a mixed microstructure of lower bainite and high carbon martensite and lower bainite, respectively. The carburizing steel which has a same level as the drill bit abroad was obtained by designing the new heat treatment cooling process.
|
|
Published: 02 May 2018
|
|
|
|
|
1 Hu Zhiguo. The research and development of bit steel and drilling bit products [J]. Rock Drilling Machines Pneumatic Tools,2011(4):6(in Chinese).
胡支国.钎钢钎具产品的研制与开发[J].凿岩机械气动工具,2011(4):6.
2 Zhou Aimin. The national development of the process and equipment of drilling and blasting in hard rock mine [J]. Rock Drilling Machines Pneumatic Tools,2009(1):50(in Chinese).
周爱民.我国硬岩矿山凿岩爆破工艺与装备进展[J].凿岩机械气动工具,2009(1):50.
3 Farfan S, Rubio-Gonzalez C, Mesmacque G. High cycle fatigue, low cycle fatigue and failure modes of a carburized steel [J]. Int J Fatigue,2004,26(2):673.
4 Fuchs H O, Stephens R I. Metal fatigue in engineering [M]. New York: John Wiley,1980.
5 Ebert L J. The role of residual stresses in the mechanical perfor-mance of case carburized steels [J]. Metall Trans A,1978,9(11):1537.
6 Luther R G, Williams T R G. Influence of surface reinforcement on the fatigue strength of low-C steel [J]. Metall Metal Forming,1974,41(3):72.
7 Genel K, Demirkol M. Effect of case depth on fatigue performance of AISI 8620 carburized steel[J]. Int J Fatigue,1999,21(2):207.
8 洪达灵,顾太和,徐曙光.钎钢与钎具[J].北京:冶金工业出版社,2000.
9 Wang Jingqi, Lu Rong, Cui Guoli. Comprehensive evaluation on service life of drill steels [J]. Mech Ind School Shenyang City,1996,18(S1):19(in Chinese).
王晶琪,吕荣,崔国利.钎具钢使用寿命的综合评判 [J].沈阳工业大学学报,1996,18(S1):19.
10 Deng Qun, Rao Jianhua, Ye Lingyun. Experiment study of heat treatment for 23CrNi3Mo [J]. J Hubei University of Technology,2007,22(4):9(in Chinese).
邓群,饶建华,叶凌云.23CrNi3Mo 热处理工艺的试验研究 [J].湖北工业大学学报,2007,22(4):9.
11 林慧国,傅代直.钢的奥氏体转变曲线——原理、测试与应用 [M].北京:机械工业出版社,1988.
12 Quidort D, Bréchet Y. The role of carbon on the kinetics of bainite transformation in steels [J]. Scripta Mater,2002,47(3):151.
13 Bhadeshia H, Edmonds D V. The mechanism of bainite formation in steels [J]. Acta Metall,1980,28(9):1265.
14 Akita M, Tokaji K. Effect of carburizing on notch fatigue behaviour in AISI 316 austenitic stainless steel[J]. Surf Coat Technol,2006,200(20):6073.
15 Tomita Y, Okabayashi K. Mechanical properties of 0.40 pct C-Ni-Cr-Mo high strength steel having a mixed structure of martensite and bainite[J]. Metall Mater Trans A,1985,16(1):73.
16 Tomita Y, Okabayashi K. Improvement in lower temperature mechanical properties of 0.40 pct C-Ni-Cr-Mo ultrahigh strength steel with the second phase lower bainite[J]. Metall Mater Trans A,1983,14(2):485.
17 Tomita Y, Okabayashi K. Heat treatment for improvement in lower temperature mechanical properties of 0.40 pct C-Cr-Mo ultrahigh strength steel[J]. Metall Mater Trans A,1983,14(11):2387.
18 Tomita Y, Okawa T. Effect of modified heat treatment on mechanical properties of 300M steel[J]. Mater Sci Technol,1995,11(3):245.
19 Tomita Y. Mechanical properties of modified heat treated silicon modified 4330 steel[J]. Mater Sci Technol,1995,11(3):259.
20 Ghosh A, Ray A, Chakrabarti D, et al. Cleavage initiation in steel: Competition between large grains and large particles[J]. Mater Sci Eng A,2013,561:126.
21 Chakrabarti D, Strangwood M, Davis C. Effect of bimodal grain size distribution on scatter in toughness[J]. Metall Mater Trans A,2009,40(4):780.
22 Fang Hongsheng, Liu Dongyu. The latest advancement of carbide free bainite/martensite duplex phase steel [J]. Heat Treat Met,2001,26(10):4(in Chinese).
方鸿生,刘东雨.无碳化物贝氏体/马氏体复相钢的新进展[J].金属热处理,2001,26(10):4.
23 Tian Baohong, Zheng Shian. The strengthening and toughening mechanisms and application of the combined microstructure of martensite and lower bainite [J]. J Luoyang Institute of Technology,1993,14(4):29(in Chinese).
田保红,郑世安.马氏体-下贝氏体复相组织强韧化机理研究及实际应用[J].洛阳工学院学报,1993,14(4):29.
|
|
|
|
渝公网安备50019002502923号 © Editorial Office of Materials Reports.
2017, Vol. 31 
