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本文对火力发电设备常用的20、15CrMo、12Cr1MoV、10CrMo910、12MoVWBSiRe 及12Cr3MoVSiTiB(11)钢的不完全正火组织,作了组织稳定性试验。在550℃温度下,20钢不完全正火组织,与正常组织比是不稳定的,球化倾向大,当工作温度达540℃时,只要2000小时就将有石墨点出现。不完全正火组织的危害性,不能通过再次正常回火予以挽救。当达到中度球化之后,与进一步球化的同时,伴随着石墨化的进行。在相同试验条件下,12Cr1MoV 钢不完全正火组织与正常组织的稳定性基本相同。其石墨化倾向非常小,在试验条件范围内,即使达到完全球化,也未出现石墨点。不完全正火组织对10CrMo910钢组织稳定性有明显的影响,630℃以上,该钢组织不稳定。这种钢石墨化倾向小。15CrMo 钢和10CrMo910钢组织稳定性的特性相同。不完全正火组织对12MoVWBSiRe 和12Cr3MoVSiTiB 钢未显示出不利的影响。本文从合金化理论分析了不同类型钢具有不同组织稳定特性的机理,并讨论了焊缝不完全正火区的影响。
In this paper, we investigate the tissue stability of incompletely normalized structures of 20, 15CrMo, 12Cr1MoV, 10CrMo910, 12MoVWBSiRe and 12Cr3MoVSiTiB (11) steels commonly used in thermal power plants. In 550 ℃ temperature, 20 steel is not completely normalized organization, compared with the normal tissue is unstable, the tendency of spheroidization, when the operating temperature of 540 ℃, as long as 2000 hours there will be graphite spots. Not completely normalizing the harmfulness of tissue can not be salvaged by normal tempering again. After reaching a moderate spheroidization, with the further spheroidization, accompanied by graphitization. Under the same experimental conditions, the stability of incompletely normalized 12Cr1MoV steel is similar to normal tissue. The graphitization tendencies are very small, and within the range of experimental conditions, no graphite dots appear even after complete spheroidisation. Incompletely normalized microstructure has obvious effect on the stability of 10CrMo910 steel. When the temperature is above 630 ℃, the microstructure of the steel is not stable. This kind of steel tends to be less graphitized. 15CrMo steel and 10CrMo910 steel the same stability characteristics of the organization. Incompletely normalized tissue did not show adverse effects on 12MoVWBSiRe and 12Cr3MoVSiTiB steels. In this paper, the mechanism of different types of steels with different microstructures was analyzed from the alloying theory, and the influence of incompletely normalized weld zone was discussed.