热处理工艺对AISI 4140钢组织和性能的影响（英文）
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摘要
采用光学显微镜(OM)和扫描电镜(SEM)研究了不同正火和回火温度下改性AISI 4140钢的显微组织,采用透射电镜(TEM)和选区电子衍射(SAED)观察分析了其碳化物的类型、尺寸和形态,还对改性AISI 4140钢的硬度、拉伸性能、冲击韧性进行了测试。结果表明:在850～900℃的正火处理过程中,随着正火温度的升高,平均晶粒尺寸保持在14μm左右;当正火温度达到925℃时,平均晶粒尺寸达到20μm以上,导致力学性能下降;马氏体硬度随正火温度的升高先升高后下降,880℃时达到最大值497 HV10;随着回火温度的升高(580～620℃),实验钢中的M_3C碳化物变短、变厚,屈服强度从1044 MPa下降到855 MPa,冲击韧性(-18℃)从55 J提高到108 J,这是由于位错密度较低及析出物较多导致的。
Microstructure of modified AISI 4140 steel at different normalizing and tempering temperatures was studied by means of optical microscope(OM) and scanning electron microscopy(SEM). The types, morphology and size of carbides were observed and analyzed by transmission electron microscopy(TEM) and selective area electron diffraction(SAED). The hardness, tensile properties and impact toughness of the modified AISI 4140 steel were also tested. The results show that the average grain size of the modified AISI 4140 steel remains about 14 μm with the increase of normalizing temperature in the range of 850-900 ℃, and the average grain size reaches more than 20 μm when the normalizing temperature is 925 ℃, which results in the decrease of mechanical properties. The hardness of martensite increases first and then decreases with the increase of normalizing temperature, and reaches the maximum value of 497 HV10 at normalizing temperature of 880 ℃. With the increase of tempering temperature(580-620 ℃), the M_3C carbides in the experimental steel become shorter and thicker, and the yield strength decreases from 1044 MPa to 855 MPa, impact toughness(-18 ℃) increases from 55 J to 108 J, which is due to the low dislocation density and more precipitates.
Microstructure of modified AISI 4140 steel at different normalizing and tempering temperatures was studied by means of optical microscope(OM) and scanning electron microscopy(SEM). The types, morphology and size of carbides were observed and analyzed by transmission electron microscopy(TEM) and selective area electron diffraction(SAED). The hardness, tensile properties and impact toughness of the modified AISI 4140 steel were also tested. The results show that the average grain size of the modified AISI 4140 steel remains about 14 μm with the increase of normalizing temperature in the range of 850-900 ℃, and the average grain size reaches more than 20 μm when the normalizing temperature is 925 ℃, which results in the decrease of mechanical properties. The hardness of martensite increases first and then decreases with the increase of normalizing temperature, and reaches the maximum value of 497 HV10 at normalizing temperature of 880 ℃. With the increase of tempering temperature(580-620 ℃), the M_3C carbides in the experimental steel become shorter and thicker, and the yield strength decreases from 1044 MPa to 855 MPa, impact toughness(-18 ℃) increases from 55 J to 108 J, which is due to the low dislocation density and more precipitates.
引文
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[14] Zhao M C,Yang K.Strengthening and improvement of sulfide stress cracking resistance in acicular ferrtite pipeline steels by nano-sized carbonitrides[J].Scripta Materialia,2005,52(9),881-886.
[15] ASTM E23-07a:Standard test method for notched bar impact testing of metallic materials[S].American Society of Testing and Materials,Philadelphia,2007.
[2] Zhao M C,Tang B,Shan Y Y,et al.Role of micro-structure on sulfide stress cracking of oil and gas pipeline steel[J].Metallurgical and Materials Transactions A,2003,34(5).1089-1096.
[3] Charbonnier J C,MargotMarette H,Brass A M,et al.Sulfide stress cracking of high-strength modified Cr-Mo steels[J].Metallurgical and Materials Transactions A,1985,16(5):935-944.
[4] Aucouturier M,Interrante C G,Pressouyre G M,et al.Current solutions to hydrogen problems in steels[J].American Society for Metals,Park,OH,1982,7(8).687-690.
[5] Kimura Mctal.Sulfide stress cracking of line pipe[J].Corrosion,1989,45(4):340-346.
[6] Chavane A,Habashi M,Pressouyre G M.et al.High-strength steels with improved sulfide stress cracking resistance[J].National Association of Corrosion Engineers,1986,43(1):54-61.
[7] Garber R,Wada T,Fletcher F B,et al.Sulfide stress cracking resistant steels for heavy section wellhead components[J].American Society for Metals,1985,7(2):91-103.
[8] Snape E.Roles of composition and microstructure in sulfide cracking of steel[J].Corrosion,1968,24(9):261-282.
[9] Burley J D.Greer J B.New steel alloy and certification procedure for high pressure wellheads[C]//The 55th Annual Fall Meeting of the Society of Petroleum Engineers of AIME,Dallas,Texas,1980:1-4.
[10] Tau L,Chan S L I.Effects of ferrite/pearlite alignment on the hydrogen permeationin a AISI 4130 steel[J].Materials Letters,1996,29(1/3):143-147.
[11] Fernández J,Illescas S,Guilemany J M.Effect of microalloying elements on the austenitic grain growth in a low carbon HSLA steel[J].Material Letters,2007,61(11/12):2389-2392.
[12] Maropoulos S,Karagiannis S,Ridley N.The effect of austenitising temperature on prior austenite grain size in a low-alloy steel[J] Materials Science and Engineering A,2008,483-484:735-739.
[13] Tsuchida T,Hara T,Tsuzaki K.Relationship between microstucture and hydrogen absorption behavior in a V-bearing high strength steel[J].Tetsu-to-Hagane,2002,88(11):771-778.
[14] Zhao M C,Yang K.Strengthening and improvement of sulfide stress cracking resistance in acicular ferrtite pipeline steels by nano-sized carbonitrides[J].Scripta Materialia,2005,52(9),881-886.
[15] ASTM E23-07a:Standard test method for notched bar impact testing of metallic materials[S].American Society of Testing and Materials,Philadelphia,2007.