等温淬火对超高碳钢组织和性能的影响
Effects of Isothermal Quenching on Microstructure and Mechanical Properties of Ultra-high Carbon Steel
管 琴1, 孔令来2, 商庆云1, 李印青1
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作者单位：(1. 河北工业大学 材料学院, 天津 300132; 2. 天津职业大学, 天津 300410)
中文关键字：超高碳钢； 贝氏体； 等温淬火； 冲击韧度
英文关键字：ultra-high carbon steel; bainite; austempering; impact toughness
中文摘要：对不同等温淬火工艺下超高碳钢贝氏体组织形态及力学性能进行了研究。 结果表明，较低的等温温度(250 ℃)下，贝氏体转变孕育期较长(30 min)，转变速度慢，但贝氏体可转变彻底。等温温度升高到300～350 ℃，孕育期显著缩短到10～5 min，贝氏体不完全转变显著，等温时间延长，未转变奥氏体发生非整形铁素体和渗碳体分解。在贝氏体转变量较少时，随后采取空冷，与水冷相比，贝氏体转变较多。经250 ℃ × 90 min等温淬火处理，获得下贝氏体组织及残留碳化物，表现出高硬度和良好的冲击韧度
英文摘要：The microstructure and mechanical properties of ultrahigh carbon steel austempered under isothermal temperature of 250 ℃ ～350 ℃ were studied. The results show that the incubation period(30 min) of bainitic transformation isothermal treated at 250 ℃ is longer and transformation velocity is slow, but bainitic transformation is complete. While isothermal temperature elevates as high as 300 ℃～350 ℃, the incubation period is shortened as 10～5 min, the incomplete bainitic transformation occurs, meanwhile, the untransformed austenite decomposes into cementite and allotriomorphic ferrite under long isothermal time. At the beginning of bainitic transformation with little bainite formation, bainite continues to form by air-cooling to room temperature. The high hardeness and high impact toughness of UHCs with dominated bainite microstructure was exhibited by austempering process with low holding temperature as 250 ℃ and long holding time.