The properties of high toughness low-temperature −70°C steel 09MnNiDR
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The properties of high toughness low-temperature 2708C steel 09MnNiDR Xiao Chen * , Aimin Guo, Hanxiong Dong, Shuriu Li National Enterprise Technology Centre of Wuhan Iron and Steel (Group) Co., 28 Yejin Road, Qingshan District, Wuhan, Hubei 430080, People’s Republic of China Received 1 September 1998; accepted 28 September 1998 Abstract The weldability and comprehensive mechanical properties of steel 09MnNiDR have been researched and its practical applications in petroleum and chemical equipments are discussed. It was found that the excellent weldability and low-temperature toughness is useful in the manufacture of low-temperature pressure vessels. q 1999 Published by Elsevier Science Ltd. All rights reserved. Keywords: High toughness; Low-temperature steel; Properties 1. Preface With the rapid development of the construction of petro- leum and chemical equipment industry in China, a low- temperature steel is needed for service at 2608C or 2708C, so that there is less reliance on import which costs a large amount of money. In 1988, we started with the laboratory research and then began an industrial experi- ment using the advanced melting equipment and processing flow, so that eventually the practical properties of 09MnNiDR will reach or partly exceed those of 13MnNi63 steels. 09MnNiDR and its corresponding weld materials passed all phases of assessment of new materials used in pressure vessels, as required by the Chinese National Pressure Vessels Technology Committee. A meeting about 09MnNiDR and its corresponding weld materials was held by the Mechanics–Electrics Ministry in Changsha in December 1992. The committee highly recommended 09MnNiDR for its excellent weldability and low-tempera- ture toughness. They considered 09MnNiDR to be an ideal material for the manufacture of low-temperature holders served at 2708C. Till now, about 3000 tons of 09MnNiDR has been produced with a thickness ranging from 12 to 65 mm; using which many vessels have been made. In this article, the research of 09MnNiDR is introduced. 2. Processing flow This can be outlined as follows: Melting Iron ! KR Desulphurization ! 50 ton LD converter ! RH vacuum degassing ! continuous casting ! 2800 mm plate rolling mill ! normalizing ! inspection ! supply. 3. Technology required 3.1. Composition Typical composition ranges are shown in Table 1. 3.2. Mechanical properties These are summarized in Table 2. 4. Mechanical properties 4.1. Tensile test The results are shown in Table 3. 4.2. Low-temperature tensile test As shown in Table 4, the tensile strength increases slightly with decreasing experiment temperature; the elon- gation and reduction of area remain almost unchanged with the experimental temperature. International Journal of Pressure Vessels and Piping 76 (1999) 13–17 0308-0161/99/$ - see front matter q 1999 Published by Elsevier Science Ltd. All rights reserved. PII: S0308-0161(98)00110-0 * Corresponding author.
Transcript of The properties of high toughness low-temperature −70°C steel 09MnNiDR
The properties of high toughness low-temperature2708C steel09MnNiDR
Xiao Chen*, Aimin Guo, Hanxiong Dong, Shuriu Li
National Enterprise Technology Centre of Wuhan Iron and Steel (Group) Co., 28 Yejin Road, Qingshan District, Wuhan, Hubei 430080,People’s Republic of China
Received 1 September 1998; accepted 28 September 1998
Abstract
The weldability and comprehensive mechanical properties of steel 09MnNiDR have been researched and its practical applications inpetroleum and chemical equipments are discussed. It was found that the excellent weldability and low-temperature toughness is useful in themanufacture of low-temperature pressure vessels.q 1999 Published by Elsevier Science Ltd. All rights reserved.
Keywords:High toughness; Low-temperature steel; Properties
1. Preface
With the rapid development of the construction of petro-leum and chemical equipment industry in China, a low-temperature steel is needed for service at2608C or2708C, so that there is less reliance on import whichcosts a large amount of money. In 1988, we started withthe laboratory research and then began an industrial experi-ment using the advanced melting equipment and processingflow, so that eventually the practical properties of09MnNiDR will reach or partly exceed those of13MnNi63 steels.
09MnNiDR and its corresponding weld materials passedall phases of assessment of new materials used in pressurevessels, as required by the Chinese National PressureVessels Technology Committee. A meeting about09MnNiDR and its corresponding weld materials was heldby the Mechanics–Electrics Ministry in Changsha inDecember 1992. The committee highly recommended09MnNiDR for its excellent weldability and low-tempera-ture toughness. They considered 09MnNiDR to be an idealmaterial for the manufacture of low-temperature holdersserved at2708C.
Till now, about 3000 tons of 09MnNiDR has beenproduced with a thickness ranging from 12 to 65 mm;using which many vessels have been made. In this article,the research of 09MnNiDR is introduced.
2. Processing flow
This can be outlined as follows:Melting Iron ! KR Desulphurization! 50 ton LD
converter ! RH vacuum degassing! continuouscasting! 2800 mm plate rolling mill! normalizing!inspection! supply.
3. Technology required
3.1. Composition
Typical composition ranges are shown in Table 1.
3.2. Mechanical properties
These are summarized in Table 2.
4. Mechanical properties
4.1. Tensile test
The results are shown in Table 3.
4.2. Low-temperature tensile test
As shown in Table 4, the tensile strength increasesslightly with decreasing experiment temperature; the elon-gation and reduction of area remain almost unchanged withthe experimental temperature.
International Journal of Pressure Vessels and Piping 76 (1999) 13–17
0308-0161/99/$ - see front matterq 1999 Published by Elsevier Science Ltd. All rights reserved.PII: S0308-0161(98)00110-0
* Corresponding author.
4.3. High-temperature tensile test
Table 5 shows that with the increase of experimentaltemperature, yield point and tensile strength decreaseslowly, while elongation and reduction of area have anobvious increase.
X. Chen et al. / International Journal of Pressure Vessels and Piping 76 (1999) 13–1714
Table 1Chemical composition (%) (if necessary other alloys can be added).
C Si Mn P S Ni Nb Als
# 0.12 0.15–0.50 1.20–1.60 # 0.025 # 0.015 0.30–0.80 # 0.040 $ 0.015
Table 2Mechanical properties.
Condition Tensile test Impact test Bend testThickness (mm) s s (MPa) sb (MPa) d5 (%) Experimental temperature (8C) Akv (J) b � 2a 1808
Anneal or 10–16 $ 300 440–570Anneal 1 . 16–36 $ 280 430–560 $ 23 270 $ 31 d � 2aTemper . 36–60 $ 270
Table 3Results of tensile test.
Grade Thickness (mm) Sampling location Sampling orientation YP (MPa) TS (MPa) d5 (%) c (%)
09MnNiDR 16 t/2 L 455 435 515 515 36 35 78 77T 385 420 505 515 38 35 74 74
24 t/2 L 455 – 505 510 36 36 76 76T 410 – 500 505 35 34 73 75
60 t/4 L 415 415 500 500 35 41 77 78T 385 385 500 500 36 38 – –
t/2 L 410 410 505 500 33 32 76 78T 375 400 495 500 36 35 78 77
13MnNi63 24 t/2 T 390 385 575 580 29 31 75 7426 t/2 L 395 385 560 555 30 36 74 76
T 370 385 560 560 31 32 70 71
Table 4Results of low-temperature tensile
Thickness (mm) Sampling direction Sampling Location Temperature (8C) YP (MPa) TS (MPa) d5 (%) c (%)
24 T t/2 410 – 500 505 35 34 73 75240 390 395 550 545 32 32 75 75270 410 405 575 570 33 34 72 74280 440 430 590 590 34 35 70 73
Table 5Results of high-temperature tensile test.
Sampling direction Sampling location Temperature (8C) YP (MPa) TS (MPa) d5 (%) c (%)
T t/2 RT 380 – 510 – 34 –300 363 372 497 499 24 24 65 70350 338 339 498 484 28 24 73 75400 340 313 473 466 32 34 79 78450 302 312 423 411 36 34 84 81
Table 6Results ofZ-direction tensile test.
TS (MPa) c z (%)
505–525 73–75
4.4. Z-direction tensile test
A Z-direction tensile test was made on 09MnNiDR plate,t � 60 mm,d0 � 10 mm, andL0 � 1.5d0. This test wasdone at room temperature, the results of which are shown inTable 6.
From Table 6, we can find that 09MnNiDR has goodLamellar tearing resistance.
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Table 7Ductility–brittleness transition temperature and2708C impact test results
Grade Thickness (mm) Specimen orientation Sampling location vTE vTS Akv (2708C) J
09MnNiDR 16 L surface 282 280 215T 270 270 98
24 L surface , 280 280 207T , 280 255 136
60 L t/4 , 280 260 178T , 280 260 142
13MnNi63 24 L surface 275 260 153T 275 245 141
26 T surface 264 265 42
Table 8NDT temperature of 09MnNiDR.
Grade Thickness (mm) Specimen type Impact energy (J) NDT temperature (8C)
09MnNiDR 16 P3 392 26020 P2 392 , 26024 P2 392 60
13MnNiDR 24 P2 455 50
Fig. 1. V notch charpy impact test results oft � 16 mm plate. Fig. 3. V notch charpy impact test results oft � 60 mm plate.
Fig. 2. V notch charpy impact test results oft � 24 mm plate.
Table 9Results of J integral test.
Grade Thickness (mm) Temperature (8C) JIC (kJ/m2)
09MnNiDR 20 20 33213MnNi63 26 20 227
4.5. Series temperature impact
Series temperature impact curves of 16, 24, and 60 mmthick plates are shown in Figs. 1–3.
The ductility–brittle transition temperature and the Akvat 2708C are determined from series temperature impactresults (see Table 7). Here,vTE is the impact transitiontemperature by 50% maximum shelf energy, andvTS isthe fracture appearance transition temperature by 50% brit-tle grain fracture.
4.6. Nil ductility transition test
The results of a programme of nil-ductility transition test-ing are shown in Table 8.
4.7. Crack toughness test
4.7.1. JIC testAccording to ASTME 813-81 standards, the three-point-
bending method was used to determine the JIC of09MnNiDR and 13MnNi63 (Table 9).
4.7.2. COD testExperiments were carried out using the GB2038-80 stan-
dard, the results of which are shown in Table 10.
5. Effect of SR annealing on mechanical properties
The tensile and impact results of 24 mm-thick plate usingdifferent SR annealing are listed in Table 11.
6. Cold weld crack test
6.1. Maximum hardness test
A plate of thicknesst � 24 mm, was welded withf4 mm, YTW707A electrode, without preheating; the maxi-mum hardness distribution of HAZ is shown in Table 12.
6.2. Y-slit restraint cracking test
GB4675. 1-84 standard was adopted, with a platethickness of 24 and 60 mm,f 4 mm YTW707A electrode,
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Table 10COD test results.
Thickness (mm) Specimen orientation Temperature (8C) d1 (mm) d0.05 (mm)
16 T–L 20 0.271 0.310270 0.184 0.231
20 T–L 20 0.225 0.298270 0.191 0.239
24 T–L 20 0.385 0.423270 0.253 0.297
60 T–L 20 0.479 0.521270 0.358 0.413
Table 11Effect of SR treatment on tensile strength and impact test.
Plate condition Tensile test VE (J)YP (MPa) TS (MPa) d 5 (%) 208C 2608C 2708C
SR 390 535 29 243 244 251 107 124 137 150 138 121370 510 34 (246) (123) (136)
SR1 5608C × 2h 355 500 33 199 218 224 138 129 71 120 114 95360 500 36 (214) (113) (110)
SR1 6008C × 1h 360 500 36 133 131 139 94 140 122360 500 36 (134) (119)
Table 12Maximum hardness distribution (Test position interval is 0.5 mm fromposition 0 to 7, 0 is the centre of weld metal. The maximum hardness is274. Located on point 3 and 4. Near to bondline.).
Test position 0 1 2 3 4 5 6 7
Left 260 260 270 274 274 266 264 264Right 260 262 256 266 268 260 260 262
Table 13Results ofY-slit groove welding test.
Thickness (mm) Preheat (8C) Crack rate (%)Surface Section Root
24 RT 0 024 RT 0 060 50 0 6.560 50 0 0
environment temperature of 178C, and relative humidity of86%, the results are shown in Table 13.
7. Mechanical properties of welded joint
7.1. Tensile and bend test
Thickness of tensile samples was the same as the weldedplate. To determine the whole section elongation andcompact bend-samples are tested wholly by side bend, theresults are shown in Table 14.
The results reveal that the tensile strength and side bendof welded joint are qualified, no matter downhand weldingor automatic submerged-arc welling (SAW). The weldmetal matches well with the base metal.
7.2. Impact test on welded joint
See Table 15.
8. Conclusion
1. 09MnNiDR has exceedingly good low-temperaturetoughness, its practical properties are superior to thoseof 13MnNi63.
2. A proper stress relief annealing has little effect onmechanical properties of 09MnNiDR.
3. 09MnNiDR has excellent weldability.
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Table 14Results of tensile and bend test.
Thickness (mm) Weld ways Heat input (kJ/cm) TS (MPa) Split position Side bend 1008
16 Downhand vertical 12–21 540 545 Base metal Good16 Downhand 10–15 540 550 Base metal Good24 Downhand 12–18 540 545 Base metal Good16 Submerged-arc welding 20 540 540 Base metal Good16 Submerged-arc welding 25 540 540 Base metal Good24 Submerged-arc welding 20 545 550 Base metal Good
Table 15Results of impact test of welded joint.
Thickness (mm) Weld ways Heat input (kJ/cm) Temperature (8C) Akv (J)Weld HAZ
16 Downhand vertical 12–21 270 20 45 57 49 90 9316 Rewelding 10–15 270 24 62 7016 Downhand 10–15 270 39 51 67 53 118 13016 Downhand 10–15 240 70 75 8124 Downhand 12–18 270 28 41 68 190 195 19724 Downhand 12–18 270 131 137 14516 Submerged-arc 20 270 27 39 52 35 40 7816 Submerged-arc 20 260 36 40 40 62 63 7724 Submerged-arc 20 270 24 37 40 21 67 13824 Submerged-arc 260 44 47 47
