共查询到19条相似文献,搜索用时 78 毫秒
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含硅低碳贝氏体钢冷却速度与组织的关系 总被引:2,自引:0,他引:2
研究了低碳含硅贝氏体钢冷却速度对组织的影响。实验发现,在贝氏体中温区可分别转变为粒状贝氏体、粒状组织、混合组织。粒状贝氏体与粒状组织中都存在(M-A)岛。随冷速增加,岛的平均直径减小,岛的形状由颗粒状向条状、甚至膜状转变。 相似文献
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设计了一系列Mo质量分数从0.1%到0.8%的Fe-Mo-C三元模型钢.采用两种不同热处理工艺制度得到不同的组织,研究了Mo元素对耐火钢高温强度的两种强化形式:固溶强化和贝氏体相变强化.Mo可以显著提高耐火钢的高温强度,它在耐火钢中的主要高温强化机理是固溶强化.Mo质量分数不高于0.5%时,其高温固溶强化效果明显,每添加0.1%的Mo,600℃的屈服强度增量为13.71 MPa;但当Mo质量分数大于0.5%后,高温强度增幅逐渐减小.此外,贝氏体相变强化对耐火钢的高温强度也有重要影响.当贝氏体体积分数达到20%时,耐火钢的高温强度显著增加. 相似文献
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采用Nb和B合金化.在热轧状态下可得到由贝氏铁素体基体和均匀分布的M/A组元组成的粒状贝氏体组织。在这样的组织转变强化机理作用下,即使C含量圾低也可获得良好的强韧性能。研究发现γ中的固溶Nb和游离态B是粒状贝氏体形成的先决条件。而且B含量对获得完全贝氏体转变强化效果有一个临界值。B的临界值随着C含量的增加而增加。由于在γ中形成了B的C化物或固溶Nb含量减少.因而C削弱B促进贝氏体转变的效果。Mn、Mo和Ni对γ转变的影响和Nb、B的作用是类似的。说明这些合金元素对Bs温度影响的参数Mneq也由此产生了.贝氏体钢的强度和Bs温度成反比的关系得到证实。 相似文献
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12Cr1MoV钢经正火回火后组织为先共析铁素体和珠光体,有时出现粒状贝氏体。研究了12Cr1MoV钢粒状贝氏体的形成及其对高温持久性能的影响。结果表明,微量氮和火温度地粒状贝氏体的形成非常敏感,粒状贝氏体有利于提高持久断裂强度,但使时效冲击韧性有所降低。 相似文献
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Dong-Jun Choi Tae-Yeong Kim Hyun-Uk Hong Joonoh Moon Chang-Hoon Lee Dong-Ik Kim Jae-Hyeok Shim Heung Nam Han Young-Su Lee 《国际钢铁研究》2023,94(2):2200103
Herein, a series of low-Mo (0.2 wt%) fire-resistant steels with varying amounts of Ti (0.008–0.13 wt%) are investigated to study the effects of Ti on yield strength at elevated temperatures. At room temperature (RT), precipitation strengthening by nanoscale TiC precipitates is found to be the major factor for the enhanced strength. The amount of TiC precipitates and both the yield and tensile strengths increase monotonically with the Ti content. However, the yield strength ratio (YS at 600 °C divided by YS at RT) of the steel with the highest Ti content (0.13 wt%) is significantly reduced to 0.6. In contrast, the YS ratio of the steels with Ti content in the range of 0.008–0.087 wt% remains above 0.7 and increases with Ti content. The difference between the steels lies in the B content and the resultant bainite volume fraction. The steel with 0.13 wt% Ti does not contain B and has only 4% bainite, whereas the other steels contain 20 ppm B and approximately 60% bainite. Hence, a microstructure with a sufficient fraction of bainite is required to ensure strength at elevated temperatures. The properties can be further improved by Ti precipitation strengthening. 相似文献
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遇火强化型耐火钢Q420FRE的物理冶金原理与力学性能 总被引:2,自引:0,他引:2
根据微合金纳米第二相在加热升温过程中的析出特点,充分发挥微合金第二相的强化作用,提出了遇火强化型耐火钢技术新思路。与传统耐火钢相比,通过降低钼含量,可以降低钢材成本。遇火强化型耐火钢的生产工艺路径为热轧+快速冷却,抑制微合金纳米第二相在热轧板冷却过程中析出的同时,获得中低温转变组织。工业试制Nb-V-Ti-Mo复合微合金化遇火强化型耐火钢Q420FRE组织类型为细小的粒状贝氏体,力学性能满足耐火钢标准GB/T 28415—2012的要求,其中室温伸长率和-40 ℃低温冲击韧性优异。经计算,工业试制的遇火强化型耐火钢Q420FRE在600~700 ℃下的纳米MC相沉淀强化增量超过50 MPa。模拟测试表明,工业试制Q420FRE的耐火极限温度接近650 ℃,600 ℃高温回火3 h不失效,空冷至室温后屈服强度上升,具有二次耐火性。 相似文献
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《钢铁研究学报(英文版)》2011,(Z1):590-594
Trials to develop a C-Mn-Mo-Nb type fire-resistant steel have been carried out by adopting recrystallization rolling (RCR) + air cooling (AC),two-stage rolling (TSR) + AC and RCR + water cooling (WC).Both RCR and TSR followed by AC resulted in polygonal ferrite (F) + pearlite (P) microstructure,while F + bainite (B) microstructure was formed by RCR + WC.The plates with F+P microstructure show tensile strengths ≥490MPa,while those with F+B exhibit tensile strengths ≥590MPa.All the plates show favorable low yield ratios ≤ 0.75,good charpy v-notch impact property >101J at 0℃ and satisfactory high temperature strength (≥2/3 of room temperature yield strength retained at 600℃). 相似文献
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《钢铁研究学报(英文版)》2011,(Z1):903-907
In order to ensure fire-resistant property of the steel under the condition of the least molybdenum content,effects of molybdenum on microstructure and properties of the fire-resistant construction steel,specially on high temperature strength were investigated.The results show that the room temperature and high temperature strength of the steel is enhanced due to increased Mo content but the impact toughness deteriorates at the same time.The fraction of bainite in the microstructure increases with increasing Mo content while the fractions of polygonal ferrite and pearlite decrease.Comparing with the steel of adding Nb alone,it was obvious that combined addition of Mo and Nb could provide better effect in high temperature strengthening.Addition of 0.25mass% Mo in the steel containing Nb could meet fire-resistant requirements of the construction steel and provide better economical effectiveness. 相似文献
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采用Formastor-FⅡ全自动相变仪实现不同冷却速度,利用金相显微镜、扫描电子显微镜和透射电子显微镜,研究了45CrMoV钢在不同冷却速度下的组织转变规律以及回火温度对组织的影响。结果表明,随着冷却速度的变慢,45CrMoV钢的组织由马氏体变为马氏体、先共析铁素体、下贝氏体和粒状贝氏体的混合物。冷却速度进一步变慢,先共析铁素体数量增多,下贝氏体和粒状贝氏体总量减少,材料硬度不断下降;45CrMoV钢中的粒状贝氏体为岛状、颗粒状,也有不规则形状,下贝氏体铁素体板条比低碳钢和超低碳钢中的板条更宽,分布更分散,板条形态不规则;随着回火温度的升高,45CrMoV钢中的渗碳体由细针状变为细条状,最后长大为椭球状,材料强度下降,韧性上升。 相似文献
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