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钢件在锻热淬火加热时通常处于奥氏体化高温区(1100～1300℃),因而导致奥氏体晶粒粗化,淬火后得到的马氏体也较粗大。尽管一般认为,锻热淬火前粗大的奥氏体晶粒有利于提高奥氏体的稳定性,延缓过冷奥氏体的分解,因而可提高钢的淬透性。然而在材料本身具备足够淬透性的条件下,仍然希望获得细小奥氏体组织,以改善淬火回火钢的强韧性配合。 1.试验方法试验用钢:45Cr钢、直径50mm;化学成分(wt％):0.46C、0.30Si、0.64Mn、0.96Cr、0.25Ni、0.02S、P。切割下料后,分别按以下两种工艺处理样品(截面尺寸:15×15mm)。工艺(1):将坯料加热到1150℃出炉始锻,一次成型至900℃终锻,停留3～5秒后入油淬火。淬火态试样的工艺为:下料→一次锻造成型并油淬;
Steel in the forging quenching heating is usually in the austenitized high temperature zone (1100 ~ 1300 ℃), resulting in austenite grain coarsening, martensite obtained after quenching also coarser. Although it is generally believed that the coarse austenite grain size before forging quenching increases austenite stability and slows down the decomposition of undercooled austenite, thereby increasing the hardenability of the steel. However, the material itself has sufficient hardenability under the conditions, still want to obtain a small austenitic tissue to improve the toughness of quenched and tempered steel with. 1. Test Methods The test steel: 45Cr steel, diameter 50mm; chemical composition (wt%): 0.46C, 0.30Si, 0.64Mn, 0.96Cr, 0.25Ni, 0.02S, After cutting the material, the samples were processed according to the following two processes (cross-sectional size: 15 × 15 mm). Process (1): the billet is heated to 1150 ℃ baked forging, once formed to 900 ℃ final forging, stay 3 to 5 seconds after quenching into the oil. Quenching state of the sample process: cutting → a forging molding and oil quenching;