EFFECTS OF TEMPERING TEMPERATURE ON THE IMPACT TOUGHNESS OF STEEL 42CrMo

48 È 10 Vol.48 No.10 2012 10 1186 1193 ACTA METALLURGICA SINICA Oct. 2012 pp.1186 1193 ÉË 42CrMo Â Í Ø ÝÕ Ü Å «Æ ( Ì ²Á ß ¾ Ì (Ü )», ß 110016) ÚÖ Ì 42CrMo ± ³Â, Ùͺ Ó»¼Ü ÆÞ ÓÅ Ë ÞÈÐ. ¼Ï±, 42CrMo ² Ô 500 650 Ë Ü, Ùͺ É Ü. ¼Ü ÆÕĐ, 12 Ë Õ ; 500 530 Ü, Ó ¹É» Æ Õ, Ë ³ 26 44 J; 600 Ü Ó À ٠л, Ë Ù³ 104 J; 600 ÕÜ, Ù Ó Ù Ó, Ë Ó. Ó Þ» ÈÐ 42CrMo Ë ÞÄ Á. ÄÏ Ü Æ, 42CrMo, Ë, Ó Đ À Æ TG161 Ô A Ð Æ 0412 1961(2012)10 1186 08 EFFECTS OF TEMPERING TEMPERATURE ON THE IMPACT TOUGHNESS OF STEEL 42CrMo CHEN Jundan, MO Wenlin, WANG Pei, LU Shanping Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 Correspondent: LU Shanping, professor, Tel: (024)23971429, E-mail: shplu@imr.ac.cn Supported by Science and Technology Project of Liaoning Province (No.2010224008) Manuscript received 2012 06 08, in revised form 2012 07 16 ABSTRACT 42CrMo heat resistant steel is a kind of structural steel, which is widely used in structural components such as crane weight on wheel, automobile crank shaft, locomotive gear hub and so on, for its good hardening ability, high temperature strength, good creep resistance, and little quenching deformation. However, in industry application, mismatching between the strength and the toughness always occurs for 42CrMo structure components. In order to solve the problem that the strength does not match the toughness in the manufacturing process for the polar crane for the nuclear power station, the effect of tempering temperature on the morphology and distribution of carbides and the impact toughness has been investigated for steel 42CrMo in this study. The experimental results indicated that the microstructure of the quenched steel 42CrMo after 500 650 tempering was characterized by tempering sorbite. As the tempering temperature increased, the Charpy absorbed energy at 12 initially increased and then decreased. The flake carbides after 500 and 530 tempering are not evenly distributed on the original martensite boundaries, the Charpy absorbed energy are 26 and 44 J, respectively. While the granular carbides are evenly distributed in the microstructure after 600 tempering, the Charpy absorbed energy reaches a maximum value of 104 J. When the tempering temperature is higher than 600, granular carbides coarsened obviously and the Charpy absorbed energy reduced notably. The morphology and distribution of carbides is the key factor that influences the impact toughness of steel 42CrMo. Morphology and structure analysis for the carbide was carried out by TEM together with EDS analysis, the results showed that the carbide after tempering treatment is (Fe, M) 3 C and Fe, Cr, Mo are the main alloy element in the carbide. When the tempering temperature is in the range of 560 600, * Đ¹ Ò³ Đ 2010224008 ÙÍ : 2012 06 08, Ù ½ : 2012 07 16 ¾ß : ÌÔ, º, 1987 Ð, Ð DOI: 10.3724/SP.J.1037.2012.00340

10 ËÓÐ : ÛÐ 42CrMo Ê ÝÇ 1187 the uniformly distributed granular carides forms on the matrix and the impact toughness is over 60 J. As the tempering temperature continues increasing, the carbides will coarsen and the impact toughness will decrease. In order to obtain the good strength and toughness matching, for 42CrMo structure, it is recommended that the tempering temperature should be in the range of 550 590. KEY WORDS tempering temperature, steel 42CrMo, Charpy absorbed energy, carbide, ½² Í ß Ù, Û ß É Ø. ÅË ÈÆ ßÅ Ü, Õ ÛÜ, Ð ³ß Ü, Æ Û ³ Đ Ð ½ ß Ñ Ê. Öß ³  ËÛߊݹ½, ÕÑ Â Û»Ò [1] ; É, »РßÅ ÀÖ, «, µä Ú ßÏÛ, Ø«Ûß Ð Â [2,3]. Â, Å ß ß É, ɽ Ç Á ßÂ Ç ß¹. ͳ Ò Û Í ³ Í 42CrMo ², ¼ Đ ½, Â Ç ßÄ Á, Ï µ,  Đ, ÐÇ ß Û µ [4 7], Ê Í Ö Ä Î ÍÐÆ «Þ ¼ ¹Ã Ç [8 14]. È 42CrMo Ç, Õ Õ Û Í ³ Å ÏÜÁ º ¼ß, ÕÁ ¹ Éß Ô, Ì µº. Õ 42CrMo Ö Õ [11 14], Â, Ã Ñ 42CrMo» Û µßé Ç ßÆÍ ÜÅ. 42CrMo Õ Â Í À, à [15 22] ² : Ñ ÝĐ Ñ Đ Á ß» µç Ú É, Đ Á Û µß. ß 42CrMo ß Ã Õ Å¼, Å ß Ñ ¹ ß Í µ É, Õ ÝР» º Û µßé Ñß Ã. À ĐÐß 42CrMo ºÂ Ý Đ Ñ, ÝĐ Ô ±¼ßÉ ß ± ÝĐ Ì ßÉ Ñ, Å Å ß Ñ Ñ Ø. 1 Û Å¼ Í µå ß Û ³, ³ È Æ 1, Åß Ô ± ² 1 Æ. ² 1 Ø Ï GB T3077 1999 42CrMo ßÔ ±., ż Í Ô ± GB T3077 1999 42CrMo ß ± É. ³ Ã È 70 mm 40 mm 30 mm ß, ÑеÀ 3 Ý 3 Ì, Ö 1050 20 h ßÊ Ô Ñ. Ð Ñ Ô: Õ 850 4 h г, Ð 1 ² Ç Å Fig.1 Dimensional drawing of wheel (a) and level wheel (b) (unit: mm) 1 Î 42CrMo «½Î 42CrMo Õ ² Table 1 Chemical compositions of steel 42CrMo in GBT T3077 1999 and steel 42CrMo in this work (mass fraction, %) Steel 42CrMo C Si Mn S P Cr Ni Cu Mo V Nb Fe GB T3077 1999 0.44 0.24 0.64 0.005 0.008 1.04 0.06 0.11 0.18 <0.01 <0.01 Bal. This work 0.38 0.45 0.17 0.37 0.50 0.80 0.035 0.035 0.90 1.20 0.15 0.25 Bal.

1188 48 È Đ ± ÝĐ Ñ, ÝĐ ± 500, 530, 560, 580, 600, 620 650, Ê 3 h, Ç Ñ ÎÞ Æ 2. ºÂ Ñ Ôß 42CrMo Ýż, È À 5 mm ß ± Ý, Í µ ß AG 100KNG Ý ; Ì Å¼ Í Charpy V Ì Å¼, ż 12 ( Å ¼ ±ß «), È 10 mm 10 mm 55 mm ± V Ì, Ì ¼ RKP 450. µ Ê 3 ż Ê. Ý Ì ÆÐÐ, Í Hitachi S 3400N Ò (SEM) Ç Úλ, µ (EDS) ±. ºÂ Ñ Ôß Ö ß» ±. ᯐ 4%( ± ) ºÄ Ð, Í AXIOVERT 200MAT É ÚÎ (OM) SEM Ç». ± 530, 600 650 ÝĐÐß Ã, Í Gatan 656 Tenupol 5 ¾±½ ÄÚ (TEM). Í FEI µ ß Tecnai G 2 20 TEM Ç Ô ß ±¼, Â Í EDS Ô ßÔ ± ±. 2 Û Åß Ñ 2.1 ÊÌ 42CrMo à ÚÙ ÞÖ 42CrMo 850 4 h ³ÐßÏ Á σ b 1960 MPa,, Ï, Ì 4 J,», Æ 3 Æ. Æ 4 42CrMo ºÂ ÝĐ 3 h Ðß Ý µ., Õ 500 650 Ì, ½ÝĐ ß, σ b Ï Á σ s ÔÊ ß Â, ÁÔµßÊ, ÝĐ Õ 560 600, Á Ôµ Ð. ÝĐ Å 650, σ b σ s ± ԵŠ685 490 MPa. Ý ½ÝĐ, ÁÖ Ê : 560 ÝĐÐ, Ý ½Đ, 12%, 650 ÝĐÐ, Ý Ú (26%). Temperature, o C 1000 800 600 400 200 0 Quenching temperature (850 10) o C Tempering temperature 500 650 o C 0 2 4 6 8 10 12 14 16 Time, h 2 42CrMo Ð ÍÝ Fig.2 Heat treatment process curve of steel 42CrMo Æ 5 Ï 42CrMo 850 4 h ³ Ð ºÂ ÝĐÐÕ 12 ÔßÌ., Õ 500 600 ÝĐÐ, ½ÝĐ Ì Ú, 500 ÝĐÐÌ 26 J, 600 Ý ĐÐ Ú 104 J; 600 ÝĐ, Ì Ô µ, 650 ÝĐÐÌ µ 44 J; 560 620 ÝĐÐ, 12 ÔÌ Õ 59 104 J,. ÛÍ ³ Û µ É : σ b 900 MPa, σ s 650 MPa, 12 ÔßÌ A k ( 12 ) 50 J, 12 ÔßÌ ½ A k ( 12 ) min 35 J. Â, 42CrMo ³ ÐÕ 550 590 Ì Ýе ¹Á Ì ß É. 3 42CrMo ² ÞÍƺ Fig.3 OM (a) and SEM (b) images of quenched steel 42CrMo 1200 1100 1000 24 900 22 800 Tensile strength 20 Yield strength 18 700 Elongation 600 Fitted line 16 14 500 12 400 480 500 520 540 560 580 600 620 640 660 Tempering temperature, o C 4 Ü Æ 42CrMo ÀÆÞÈÐ Fig.4 Effects of tempering temperature on the strength of Strength, MPa steel 42CrMo 28 26 Elongation, %

10 CSo} : w}^ 42CrMo 4R ` yo < Charpy absorbed energy, J 120 RTj C 42CrMo Koh ~>zr 42CrMo 6 D' d. J` y Y m l { vv/ in 6 6Æ. ^, DZ 500, 530, 560, 580, 600, 620 d 650 y l, vv/ RZy 4 B, Br<p i{l d%0.j. 500 d 530 y ` 3 h l { / 8(.l, <B 6 I 5 $,. Rk % 0 q B E 4, Mf B (N 6a d b); 1y ` 9, <B $!ZZv$ m%0 (N 6c g), 600 650 y l { <B I m % 0, f B >D. v (N 6e g), b 600 y Ym{, 620 d 650 y Yml <BZv v_ p (N 6f d g). q 500 650 y, Z d{ C B 2.2 100 80 60 50 J 40 20 480 500 520 540 560 580 600 620 640 660 Tempering temperature, o C 5S (zp} g x~_æ 5 42CrMo Fig.5 Effect of tempering temperature on the Charpy absorbed energy of steel 42CrMo g 5CY&b -I_Æx~kzuU. 6 42CrMo Fig.6 Microstructures of quenched steel 42CrMo tempered at 500 600 (e), 620 (f) and 650 (g) for 3 h 1189 (a), 530 (b), 560 (c), 580 (d),

6 48 P k W, k W {Xrq4 Y F, B E4 < E4, y ` 9f B. B{XrkW. 1y ` { 9, _ )tl, E BD 500 650 y l / RZ y 4 B E'7U kw <B, vrk%0^ < α { B, Y^ <B{ l d%0. J t w! B r. 1 y ` 9 5 $ <B {= d $2, ) {8(. 500 650 y Y m l, 1 y ` 9 1 FZv$ <B, ry `?Z 600, Zv B y $ Q %, B $ j p, Wh I d W, I $ <B ~_p. [Q, E$ B{y Z J t,bip)r. 1& α { g d ' gz $, AB{ g 2.3 8ej RTO>;VAZs_, 500 ry, _ g ~ p, { F Y^ ~9 42CrMo 6T ){ 06Q %Av, 1y ` { 9 %Av $ =l, α { ~y 5 q 12 p{ Charpy V TC, Z b /d o1a, J [, y `, ) O 7v f B ~9{<, T 0` Z 12. N 7 d 8 %( 1190 g -I_Æx~k 5p ozzs `in (a), 530 (b), 580 (c), 600 (d), 7 42CrMo 12 Fig.7 Low magnification fractographs of steel 42CrMo tempered at 500 620 (e) and 650 (f) after Charpy impact test at 12

10 CSo} : w}^ 42CrMo 4R ` yo < g -I_Æx~k 5p 1191 ozzs `UN 42CrMo 6y l T ) { M!J+ < p i { d%0. YvV/ O 7 1 X ^ : 1y ` 9, < piyy {5$ $!ZZv$, Y.Rk%0! v m%0 (N 6). DZ 500 d 530 y l, / < pi 6I5$y %0^f B Er. Y^5$< pi w { B9~gl{Nw, C 5$<p i9~a F V b, {y{<pi{ t V b 9 ~ l +&y { < p igu, J [T b, 8, T C% ( Z 26 d 44 J; 500 y l T az 2m a, 530 y lt a^ O 7v s[ T (N 7b), 2m, 500, L G F 2m { T X[ z$ o{ m, o{ myg bdm F (N 8b 6N); bd{wx^ O, T 0 8 42CrMo 12 Fig.8 High magnification fractographs of steel 42CrMo tempered at 500 (a), 530 (b), 580 (c), 600 (d), 620 (e) and 650 (f) after Charpy impact test at 12 (Inset in Fig.8b indicate a band of collection of dimples) >W 42CrMo 6DZ.J` y lq 12 p{j OdVOT a. ^, DZ 500 y l, a r Z # vt, I v {a (N 7a d 8a), D Z 530 y l, s[td KZ tt, #vt t, I%2m a (N 7b d 8b), b?9. 1y ` 9, q 12 pt a rzs[td KZ, Z {b a (N 7c e dn 8c e),? 600 y l abd,llz, %0Rk (N 7d d 8d), b,_. D 650 y l\ia, L a{2m8.,l (N 8f). 6 D' d. J` y Y m l, xv{ / RZ y 4 B, q < p i { d% 0. J, T C W x v 8 H, Y [ ^ O 5, {J A BpQ~ 42CrMo [23]

1192 48 È 9 42CrMo Ü º Þ TEM Å Ó Ù«Fig.9 TEM micrographs of steel 42CrMo quenched and tempered at 530 (a), 600 (b) and 650 (c), and SAD pattern analysis of carbides (d) ¾Ñ ß [24]. Ð Óß Å ß ÑÕ 650 ÝĐÐßÌ Ö Õ, 530 ÝĐÐß Õ (Æ 8a, b g), Ð 650 ÝĐÐÌ ÆĐ 530 ÝĐÐÌ, ÄÐ Ì ÊÚ 500 ßż½ ß «. 560 620 ÝĐÐ, 12 Ì Õ 59 104 J, Ì ; Úλ ÎÏ, 560 620 ÝĐ Ð» Ô Ý ºÊ ±¼ ѱ¼ (Æ 6c f), ºÊ ±¼ß Ô ß ÆÛ Â µđ, Ä Ô ½ÝĐ ß Ú, µđ ÆÛ, Ì Â ßÎ ; ÖÎ, 560 620 ÝĐÐ Ê ß (Æ 7c e), EDS ± ² ³ß Ò MnS, ÎÏ, 580 ÝĐÐ Ä Á ß, 600 620 ÝĐÐ, ÄÁ Þß,. 600 ÝĐ, C ß Ñ, Ô Å Ð,» ±¼ Ôº Ú, ÕÅ Ð ß Ô ßÊ Ð, ¹ ß ºÂ [25], Ì Â Ô Ø«Ô, 650 ÝĐÐ ÔÜ Ú. Â, Õ 500 600 Ý Đ, Ô Ñ Ú, ı¼ ºÊ Ú Ñ Ô, Ð Ì ¾Ôß Â. ÖÝĐ, Ô ß Ô Ì Ôµß Â. 2.4 ÊÌ ÈÐ TEM ÁÒ Æ 9a c Ï 530, 600 650 ÝĐÐ Ô ß TEM., ÝĐл Ô Ê (Fe, M) 3 C, ß ½ÝĐ Ú, 600 Ô. EDS ± ½ ², Fe, Cr Mo, Cr Mo, ¹Ú ± ½ Æ 9d. 3 (1) 42CrMo ³Ð», Õ 500 650 ÝĐ, Ï Á Ï Á ½ÝĐ ÁÖ ÐÔµßÊ, 560 600 Ôµ ½Ð. 12 Ì ½ÝĐ, ÁÖ ÐÔµßÊ, ÝĐ 600 Ú 104 J. Æ ÛÍ

10 ËÓÐ : ÛÐ 42CrMo Ê ÝÇ 1193 µ É, Å 42CrMo Æ¼Õ Ñß ³ÝĐ ßÁ ¼, ² ÝĐ Õ 550 590 ³. (2) 42CrMo ³Ð 500 650 ÝĐл Ê ÝĐ, ½ÝĐ, Ô ºÊ ±¼ Ú Ñ±¼, ÖÝĐ 600 Ð, Ú Ô Ô,» ±¼ßºÂ ÝĐ É Û µß Â. 500 600 ÝĐ, Ô Ñ Ú Ä±¼ ºÊ Ú Ñß Ô Ì ¾Ôß Â, ÖÝĐ, Ô ß Ô Ì Ôµß Â. Ô [1] Li B. Master Dissertation, Shanghai Jiao Tong University, 2007 (Ò. Õ, 2007) [2] Gong B Z. Hoisting Conveying Mach, 2002; (2): 9 ( Æ. Ð, 2002; (2): 9) [3] Zhang Q F. Hoisting Conveying Mach, 2011; (3): 26 (Ü ¹. Ð, 2011; (3): 26) [4] Quan G Z, Li G S, Chen T, Wang W X, Zhang Y W, Zhou J. Mater Sci Eng, 2011; A528: 4643 [5] Holzapfel H, Schulze V, Vöhringer O, Macherauch E. Mater Sci Eng, 1998; A248: 9 [6] Sarioglu F. Mater Sci Eng, 2001; A315: 98 [7] Lin Y C, Chen M S, Zhong J. Mech Res Commun, 2008; 35: 142 [8] Ge Y S, Wang C H, Meng H Z, Lu Z Y. Heavy Cast Forg, 2005; (2): 27 ( Ë, Ì Ú, Ù, «Å. Æ, 2005; (2): 27 ) [9] Zhao L P, Liu Z C, Yang H, Feng D C. Spec Steel, 2004; 25(4): 21 (ÝÔ,, ¾ Þ, µ., 2004; 25(4): 21) [10] Liu D Z, Li Y F. Heat Treat Technol Equip, 2008; 29(3): 74 ( Æ, Òµ³. Ð, 2008; 29(3): 74) [11] Gu JJ, QinYQ,Chen Z L,LuQH.Hot Working Technol, 2010; 39(22): 160 (ÃÌ», ÅÏÈ,, ÅÇÑ., 2010; 39(22): 160) [12] Chu J H, Liu S Y. Heavy Cast Forg, 2007; (4): 6 ( Ú,. Æ, 2007; (4): 6) [13] Wang M L, Wang J, Wang L X. Bearing, 2009; (12): 37 (Ì Ó, Ì ±, ÌÕÒ. Ã, 2009; (12): 37) [14] Li J, Chen Z W, Liu D K. Heavy Cast Forg, 2000; (4): 25 (Ò,,. Æ, 2000; (4): 25) [15] Wang X T, Yao Y L, Shao T H. Acta Metall Sin, 1990; 26(6): 40 (ÌÅ, Ãß, Ø Ñ., 1990; 26(6): 40) [16] Dhua S K, Ray A, Sarma D S. Mater Sci Eng, 2001; A318: 197 [17] Liu D Y, Xu H, Yang K, Bai B Z, Fang H S. Acta Metall Sin, 2004; 40: 882 ( «,, ¾, Þ, Ð., 2004; 40: 882) [18] Gao G H, Zhang H, Bai B Z. Acta Metall Sin, 2011; 47: 513 ( ÁÚ, Ü, Þ., 2011; 47: 513) [19] Zhang C Y, Wang Q F, Ren J X, Li R X, Wang M Z, Zhang F C, Yan Z S. Mater Des, 2012; 36: 220 [20] Zhang P, Zhang F C, Wang T S. Acta Metall Sin, 2011; 47: 1038 (Ü ¾, ܹ, Ì Ð., 2011; 47: 1038) [21] Wang R F, Xu K,Xue G. Hot Work Technol, 2007; 36(16): 43 (̺,,., 2007; 36(16): 43) [22] Bakhtiari R, Ekrami A. Mater Sci Eng, 2009; A525: 159 [23] Cui Y X, Wang C L. Fracture Analysis. Harbin: Harbin Institute of Technology Press, 1998: 73 ( Ø, Ì Ö.. µ: µ Î Û, 1998: 73) [24] Wang P, Lu S P, Xiao N M, Li D Z, Li Y Y. Mater Sci Eng, 2010; A527: 3210 [25] Beachem C D. Metall Trans, 1975; 6A: 377 ( : )