稀土元素对P20钢性能的影响

研究了Ｐ２０钢中加入微量稀土元素后性能和组织的变化规律。结果表明，稀土元素的加入改变了钢中硫化物夹杂的组成和形貌，粒状复合稀土硫化物夹杂取代了条状硫化锰夹杂，从而提高了钢材的塑韧性、动态断裂韧性和等向性能。给出了钢中硫化物的长宽比与ＲＥ／Ｓ及钢的等向性能与硫化物长宽比的定量关系。

高品质热作模具钢SWPH13的性能研究

采用炉外精练、气体保护电渣重溶技术以及高温均质化处理、多向锻造、超细化处理技术研制的热作模具钢SWPH13的质量水平可与国际领先水平的瑞典ASSAB8407相媲美,标志着国产H13热作模具钢的质量水平跃上了一个新的台阶。

铈元素对H13模具钢等向性能影响的研究

对H13热作模具钢进行了Ce元素处理,配合等温球化热处理工艺,开展了对H13钢等向性能的研究。采用JBN-300摆锤式冲击试验机对冲击韧性进行了检测,采用MICROHARDNESS TESTER HV-1000显微硬度仪对显微硬度进行了检测。结果表明:随Ce含量的增加,H13钢的横、纵向力学性能呈先增加后减小的趋势,当Ce含量为0.05%时钢的等向性能有大幅提高且达到最大值91.10%;Ce元素对显微硬度影响不大;添加Ce元素钢的等向性能都有不同程度的增加。

Role of inclination angle on columnar-to-equiaxed transition in the eutectic Al-5Mg-2Si alloy fabricated by laser powder bed fusion

In this study,the effect of inclination angles relative to the building direction in the additively manufactured eutectic Al-5Mg-2Si alloy was investigated through the laser powder bed fusion(LPBF).The microstructures and mechanical properties of the Al-5Mg-2Si alloy manufactured with different inclination angles(0°,30°,45°,60°and 90°)were reported and discussed.It is found that the“semicircular”melt pool(MP)in the load bearing face of 0°sample was eventually transformed into“stripe-like”MP in the 90°sample,accompanied by an increased fraction of melt pool boundaries(MPBs).Moreover,the microstructural analysis revealed that the columnar-to-equiaxed transition(CET)of theα-Al grains and eutectic Mg2Si was completed in the 90°sample,which were significantly refined with the average size of 10.6μm and 0.44μm,respectively.It is also found that the 90°sample exhibited good combination of strength and elongation(i.e.yield strength of 393 MPa,ultimate tensile strength of 483 MPa and elongation of 8.1%).The anisotropic mechanical properties were highly associated with the refined microstructures,thermal stress,and density of MPBs.Additionally,the CET driven by inclination angles was attributed to the variation of thermal conditions inside the local MPs.

高温均匀化退火对H13钢芯棒带状偏析和冲击性能的影响

采用热轧态H13钢芯棒进行高温均匀化退火试验,研究了不同的保温温度、时间及冷速对带状偏析和冲击性能的影响。结果表明,H13钢在1250℃均匀化退火4 h,经快速冷却后,带状偏析明显减轻,二次碳化物和杂质元素在晶界偏聚倾向减小,冲击性能及等向性均得到提高。经生产实践检验,钢锭在锻造前进行1250℃均匀化处理,锻后快冷,钢材性能基本达到进口8407钢水平。