Al对淬回火H11钢力学性能和碳化物的影响

Influence of Al on mechanical properties and carbides of quenched and tempered H11 steel

研究了Al质量分数为0.77%及不含Al的H11钢在不同淬回火处理工艺下的硬度和冲击功的变化规律,并对两种钢原始退火态、1060℃淬火、1060℃淬火＋510℃回火、1060℃淬火＋560℃回火和1060℃淬火＋600℃回火处理后的试样进行碳化物萃取,同时借助扫描电子显微镜（SEM）和X射线衍射仪（XRD）分析了Al对H11钢中碳化物形态及类型的影响.结果表明：（1）Al能提高H11钢的冲击韧性和回火硬度,但会使淬火硬度有所降低.（2）Al可以促进H11钢淬火过程中碳化物的溶解和元素的均匀分布.（3）Al会阻碍H11钢回火过程中碳化物的析出和聚集,这种作用在560℃以下回火时更加显著.（4）Al可以使H11钢回火时的（Fe,Cr）2C、MoC、Cr7C3类碳化物更加稳定,抑制（Fe,Cr）3C、Mo2C和Cr（23）C6类碳化物的析出,这是因为Al可以阻碍H11钢中碳及合金元素在回火过程中的聚集.

H11 steel with mass fraction of Al（0. 77% and 0） was treated by different quenching and tempering processes,and the variation of hardness and impact energy were systematically investigated. Moreover,carbide extraction at annealed,1060 ℃quenched,1060 ℃ quenched ＋ 510 ℃ tempered,1060 ℃ quenched ＋ 560 ℃ tempered,and 1060 ℃ quenched ＋ 600 ℃ tempered were conducted. Finally,the type and morphology of carbides were analyzed by X-ray diffraction（XRD） and scanning electron microscopy（SEM）. The main conclusions are as follows：（1） Al can improve the impact toughness and tempering hardness of H11 steel;however,it reduces the hardness of quenching.（2） Al can promote the dissolution of carbides and the homogeneity of elements during the austenitizing process.（3） Al can prevent the precipitation and accumulation of carbides during the tempering process,which is more obvious under 560 ℃.（4） Al can prevent the accumulation of carbon and alloy elements,such that（Fe,Cr）2 C,Mo C and Cr7 C3 become more stable and suppresses the precipitation of（Fe,Cr）3 C,Mo2 C,and Cr_（23）C_6 during the tempering process.