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运用SEM和TEM研究了Cr5锻钢支承辊调质处理(970℃淬火+540℃回火)对碳化物形貌和类型的影响,并通过热力学理论计算了该工艺下的碳化物形成及其转变过程中的ΔH和ΔG。结果表明:调质处理前,基体组织为珠光体,碳化物尺寸约为700~800 nm,复杂六方点阵的M7C3和复杂立方的M23C6分别与α-Fe具有(112ˉ0)K//(011ˉ)α、[0001]K//[011]α和(511)K//(011ˉ)α、[116ˉ]K//[011ˉ]α晶体学位向关系;调质处理后,基体组织为回火索氏体、少量回火马氏体,并伴有未溶碳化物,碳化物尺寸明显减小,约为200 nm,其类型转变为正交点阵的M7C3碳化物,与α-Fe晶体学位向关系为(1ˉ13)K//(200)α、[5ˉ12]K//[01ˉ1]α;此外,该工艺下碳化物生成和转变的ΔH和ΔG计算值均小于零。
The effects of quenching and tempering (970 ℃ quenching + 540 ℃ tempering) on the morphology and type of carbide were studied by SEM and TEM. The formation and transformation of carbide under this process were calculated by thermodynamic theory ΔH and ΔG during the process. The results show that the matrix microstructure is pearlite and the size of carbide is about 700-800 nm before quenching and tempering. M23C6 of complex hexagonal lattice and complex cubic M23C6 have (112ˉ0) K // (011ˉ) α, [0001] K // [011] α, and (511) K // (011ˉ) α, [116ˉ] K // [011ˉ] α crystallites. After quenching and tempering, Martensite, a small amount of tempered martensite, and accompanied by undissolved carbides, carbide size was significantly reduced, about 200 nm, its type into an orthogonal lattice M7C3 carbide, and α-Fe crystal orientation The relations are (1ˉ13) K // (200) α, [5ˉ12] K // [01ˉ1] α. In addition, the calculated values of ΔH and ΔG for carbide formation and transformation are all less than zero.