In the present work,the irradiation hardening behavior of a Chinese low-activation ferritic/martensitic steel CLF-1,a candidate for fusion reactor blankets,is studied.Specimens were irradiated with high-energy14N and5...In the present work,the irradiation hardening behavior of a Chinese low-activation ferritic/martensitic steel CLF-1,a candidate for fusion reactor blankets,is studied.Specimens were irradiated with high-energy14N and56Fe ions at the terminal of a cyclotron to three successively increasing damage levels of 0.05,0.1 and 0.2 displacements per atom(dpa)at about-50°C.The energy of the incident ions was dispersed to 11 successively decreasing grades using an energy degrader,thereby generating an atomic displacement damage plateau in the specimens from the surface to a depth of 25μm,which is sufficiently broad for the Vickers hardness test.Eight different loads(i.e.98 mN,196 m N,490 m N,980 m N,1.96 N,4.9 N,9.8 N and 19.6 N)were applied to the specimens to obtain the depth profiles of the Vickers hardness by using a microhardness tester.Hardening was observable at the lowest damage level,and increased with increasing irradiation dose.A power-law correlation of the Vickers hardness with the damage level(HV0=1.49+0.76 dpa0.31)is proposed.Testing with a nano-indentation technique was also performed,and a linear relationship between the Vickers micro-hardness and the nanohardness(HV0=0.83 H0)was observed.A comparison with other RAFM steels(CLAM,JLF-1,F82 H,EUROFER97 etc.)under neutron or charged particle irradiation conditions shows that most of the RAFM steels exhibit similar power-law exponents in the dose dependence of irradiation hardening.The difference in the irradiation hardening may be attributed to differences in microstructure prior to irradiation.展开更多
低活化铁素体/马氏体耐热(RAFM)钢在强辐照条件下仍具有良好的力学性能、导热性及抗热膨胀性,被认为是目前核聚变反应堆的首选结构材料,但是其较低的高温蠕变抗力和抗辐照性能极大限制了其使用温度,进而影响了核聚变反应堆的转换效率。...低活化铁素体/马氏体耐热(RAFM)钢在强辐照条件下仍具有良好的力学性能、导热性及抗热膨胀性,被认为是目前核聚变反应堆的首选结构材料,但是其较低的高温蠕变抗力和抗辐照性能极大限制了其使用温度,进而影响了核聚变反应堆的转换效率。纳米级MX型碳氮化物作为钢中重要的强化相,在高温下仍具有良好的稳定性,能够有效阻碍位错的运动及湮灭,可以有效提高钢的高温蠕变性能。此外,纳米级MX型碳氮化物的析出还可以增加钢中的界面比,而界面是良好的缺陷陷阱,可以有效诱捕辐照产生的离位原子、空位等点缺陷,从而提高钢的抗辐照性能,因此进一步增加钢中的MX型碳氮化物含量被认为是提升RAFM钢力学性能的有效途径。目前,提高RAFM钢中MX型碳氮化物强化最有效的方式主要有三种:氮化物强化工艺、形变热处理工艺(TMT)和Ti元素的添加工艺。三种工艺均能有效提高钢的高温拉伸及蠕变性能,但它们对钢综合力学性能的影响并不完全相同。氮化物强化工艺主要是通过降低钢中的C含量同时提高N含量,从而达到促进MX型碳氮化物析出的目的。但由于钢中的N含量较高,极易形成粗大的TaN夹杂,在低温条件下,钢的临界裂纹尺寸会大幅降低,TaN夹杂就会成为冲击过程的裂纹源,从而使钢的韧脆转变温度(DBTT)大幅升高。TMT工艺主要是将钢加热到奥氏体化温度以上进行保温,使钢中碳化物充分溶解,之后降温至M 23 C 6型碳化物熔点以上,对钢引入较大的变形量,从而产生大量位错,促进MX型碳氮化物的形核。由于较高的固溶温度和较大的变形量,TMT处理后,钢具有较大的晶粒尺寸和较高的应力状态,从而使钢的冲击性能大幅降低。Ti元素添加工艺主要是在钢中引入Ti元素,Ti是良好的碳氮化物形成元素,在钢中极易与C、N元素结合形成MX型碳氮化物,从而提高钢中的MX型碳氮化物含量。与氮化物强化及TMT工艺不同,Ti元素添加后,钢中并未出现粗大的夹杂物及过大尺寸的晶粒,其表现出最佳的综合力学性能,与传统RAFM钢相比,其高温力学性能及室温冲击性能均大幅增加,仅DBTT值略有升高。本文从强化机理出发,重点介绍了近年来MX型碳氮化物强化RAFM钢的发展情况,并分析对比了三种MX型碳氮化物强化工艺对钢综合力学性能的影响。此外本文还指出了RAFM钢未来发展过程中可能遇到的其他问题,并对今后的研发重点进行了简要的分析。展开更多
基金sponsored by the National Magnetic Confinement Fusion Program(No.2011GB108003)National Natural Science Foundation of China(No.U1532262)。
文摘In the present work,the irradiation hardening behavior of a Chinese low-activation ferritic/martensitic steel CLF-1,a candidate for fusion reactor blankets,is studied.Specimens were irradiated with high-energy14N and56Fe ions at the terminal of a cyclotron to three successively increasing damage levels of 0.05,0.1 and 0.2 displacements per atom(dpa)at about-50°C.The energy of the incident ions was dispersed to 11 successively decreasing grades using an energy degrader,thereby generating an atomic displacement damage plateau in the specimens from the surface to a depth of 25μm,which is sufficiently broad for the Vickers hardness test.Eight different loads(i.e.98 mN,196 m N,490 m N,980 m N,1.96 N,4.9 N,9.8 N and 19.6 N)were applied to the specimens to obtain the depth profiles of the Vickers hardness by using a microhardness tester.Hardening was observable at the lowest damage level,and increased with increasing irradiation dose.A power-law correlation of the Vickers hardness with the damage level(HV0=1.49+0.76 dpa0.31)is proposed.Testing with a nano-indentation technique was also performed,and a linear relationship between the Vickers micro-hardness and the nanohardness(HV0=0.83 H0)was observed.A comparison with other RAFM steels(CLAM,JLF-1,F82 H,EUROFER97 etc.)under neutron or charged particle irradiation conditions shows that most of the RAFM steels exhibit similar power-law exponents in the dose dependence of irradiation hardening.The difference in the irradiation hardening may be attributed to differences in microstructure prior to irradiation.
文摘低活化铁素体/马氏体耐热(RAFM)钢在强辐照条件下仍具有良好的力学性能、导热性及抗热膨胀性,被认为是目前核聚变反应堆的首选结构材料,但是其较低的高温蠕变抗力和抗辐照性能极大限制了其使用温度,进而影响了核聚变反应堆的转换效率。纳米级MX型碳氮化物作为钢中重要的强化相,在高温下仍具有良好的稳定性,能够有效阻碍位错的运动及湮灭,可以有效提高钢的高温蠕变性能。此外,纳米级MX型碳氮化物的析出还可以增加钢中的界面比,而界面是良好的缺陷陷阱,可以有效诱捕辐照产生的离位原子、空位等点缺陷,从而提高钢的抗辐照性能,因此进一步增加钢中的MX型碳氮化物含量被认为是提升RAFM钢力学性能的有效途径。目前,提高RAFM钢中MX型碳氮化物强化最有效的方式主要有三种:氮化物强化工艺、形变热处理工艺(TMT)和Ti元素的添加工艺。三种工艺均能有效提高钢的高温拉伸及蠕变性能,但它们对钢综合力学性能的影响并不完全相同。氮化物强化工艺主要是通过降低钢中的C含量同时提高N含量,从而达到促进MX型碳氮化物析出的目的。但由于钢中的N含量较高,极易形成粗大的TaN夹杂,在低温条件下,钢的临界裂纹尺寸会大幅降低,TaN夹杂就会成为冲击过程的裂纹源,从而使钢的韧脆转变温度(DBTT)大幅升高。TMT工艺主要是将钢加热到奥氏体化温度以上进行保温,使钢中碳化物充分溶解,之后降温至M 23 C 6型碳化物熔点以上,对钢引入较大的变形量,从而产生大量位错,促进MX型碳氮化物的形核。由于较高的固溶温度和较大的变形量,TMT处理后,钢具有较大的晶粒尺寸和较高的应力状态,从而使钢的冲击性能大幅降低。Ti元素添加工艺主要是在钢中引入Ti元素,Ti是良好的碳氮化物形成元素,在钢中极易与C、N元素结合形成MX型碳氮化物,从而提高钢中的MX型碳氮化物含量。与氮化物强化及TMT工艺不同,Ti元素添加后,钢中并未出现粗大的夹杂物及过大尺寸的晶粒,其表现出最佳的综合力学性能,与传统RAFM钢相比,其高温力学性能及室温冲击性能均大幅增加,仅DBTT值略有升高。本文从强化机理出发,重点介绍了近年来MX型碳氮化物强化RAFM钢的发展情况,并分析对比了三种MX型碳氮化物强化工艺对钢综合力学性能的影响。此外本文还指出了RAFM钢未来发展过程中可能遇到的其他问题,并对今后的研发重点进行了简要的分析。
