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以30CrMnSi、40CrNiMo和37CrNi3钢进行几种加热工艺的试验结果表明,钢的加热温度、加热速度,原始组织和加热后是否保存原始奥氏体晶界都影响钢的晶粒大小和断口。除证实Садовский所指出钢的组织遗传性(如缓慢加热引起晶粒大小和断口的遗传性,加热至再结晶温度能使晶粒和断口细化)外,还发现,当加热后仍保持原始奥氏体晶界时,晶粒虽经细化,但断口仍属粗大,韧性较低。实验揭示,这是由于碳化铬在晶界存在所致。因此,碳化物在晶界的富集应成为过热以及组织和断口遗传性的一种机制。37CrNi3钢过热后任何加热工艺都保留原始晶界,因此不能导致韧性回复。经常发现,原始组织为非平衡组织(马氏体、贝氏体、魏氏组织等)的一些钢,当加热到Ac_3以上时,奥氏体化过程并不伴随着组织的细化,所形成的新的奥氏体晶粒恢复或继承了原始粗大奥氏体晶粒,这就是所谓的组织遗传性。以往一些工作,尤其是苏联Садовский学派的一系列工作对此虽作了比较深入的阐述,但对遗传性所表现的现象还需补充,产生遗传性的原因还有待进一步讨论。本文研究三种合金结构钢的不同加热速度,加热方法对组织和断口遗传性的影响,特别注意了晶界上富集相的作用,这一点对断口遗传性和性能应该起很大的影响,但目前尚未引起国内外的足够注意。
The experimental results of several heating processes with 30CrMnSi, 40CrNiMo and 37CrNi3 steels show that the heating temperature, heating rate, the original microstructure and the preservation of the original austenite grain boundaries after heating affect the grain size and fracture of the steel. In addition to confirming that Садовский indicates the tissue heredity of the steel (eg, slow heating causes grain size and fracture inheritance, heating to a recrystallization temperature allows grain and fracture refinement), it is also found that when heated, the original Austrian When the grain boundary, the grain refinement, but the fracture is still coarse, toughness is low. Experiments revealed that this is due to the presence of chromium carbides in the grain boundaries. Therefore, the enrichment of carbides at grain boundaries should become a mechanism of overheating and geneticity of the tissue and the fracture. 37CrNi3 steel overheating any heating process to retain the original grain boundaries, it can not lead to toughness recovery. It is often found that some of the steels whose primary structure is unbalanced (martensite, bainite, Widmanstatten, etc.) are not accompanied by refinement of the structure when heated above Ac 3 The new austenite grains restore or inherit the original coarse austenite grains, which is called tissue heredity. A series of previous work, especially the Soviet Union Садовский school of work made a more in-depth elaboration, but the phenomenon of the hereditary needs to be added, the causes of genetic causes remains to be further discussed. In this paper, the effects of different heating rates and heating methods on the hereditary properties of the microstructure and fracture were studied, and the effect of the enrichment phase on the grain boundary was studied. This point should have great influence on the inheritance and properties of the fracture. However, not enough attention has been drawn at home and abroad so far.