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国内外许多试验研究工作表明:低碳马氏体是高强度、大韧性相结合的组织状态。然而低碳钢或低碳合金钢的淬透性毕竟是较低的,在增大截面尺寸,心部获得非马氏体分解产物时,其综合机械性能变化规律如何?迄今还缺乏这方面的研究报导,为此本文通过试验,寻找了15、25、20Cr、和18CrMnTi四种钢,经过强烈淬火,保证心部获得100%、90%及50%低碳马氏体的最大钢棒直径,并同时分析研究了不同直径的上述四种钢心部非马氏体分解产物的变化规律及其对性能的影响。大截面静拉伸和扭转试验结果表明:试样心部出现10%的铁素体,对各项性能指标影响甚微,从静强度来说一般均在140～120公斤/毫米~2左右的高强度钢的强度范围,而心部出现10%以下屈氏体和铁素体时,虽有一定影响,但影响程度不大,心部组织中出现大量铁素体或屈氏体,性能将大大恶化。18CrMnTi钢大截面心部冲击值的模拟试验表明,心部出现20%的铁素体,室温冲击值在8公斤一米/厘米~2左右,而在-70℃时仍达6公斤一米厘米~2这说明非马氏体分解产物对低碳马氏体的脆性倾向影响较小,这是很可贵的。
Many experimental studies at home and abroad show that low-carbon martensite is a combination of high strength and high toughness. However, the hardenability of low-carbon steel or low-carbon alloy steel is, after all, low, and the law of comprehensive mechanical properties changes when increasing the cross-sectional dimension and obtaining non-martensite decomposition products in the heart. According to the research reports, four kinds of steels, 15, 25, 20Cr and 18CrMnTi, were found for the purpose of this study. After quenching, the maximal rod diameter of 100%, 90% and 50% At the same time, the variation regularity of the non-martensite decomposition products of the above-mentioned four kinds of steel with different diameters and the influence on the performance were analyzed. The results of large-area static tensile test and torsion test show that 10% ferrite appears in the heart of the sample, and has little effect on various performance indexes. The static strength is generally about 140 to 120 kg / mm 2 The strength of high strength steel range, and the heart appears below 10% troostite and ferrite, although some impact, but little effect, there is a lot of heart tissue ferrite or troostite, the performance will be Greatly worse. The simulation results of the large cross-section heart impact value of 18CrMnTi steel show that 20% of the ferrite appears in the heart, and the impact value at room temperature is about 8 kg / m ~ 2 while it still reaches 6 kg / m ~ 2 at -70 ° C ~ 2 This shows that non-martensitic decomposition products have a small effect on the brittleness tendency of low-carbon martensite, which is very valuable.