【摘要】 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。更多还原

【Abstract】 The effect of quenching(970 ℃) and tempering(540 ℃) on microstructure and style of carbide in Cr5 forged steel backup roll were studied by SEM and TEM. The ΔH and ΔG of formation and transformation were calculated by thermodynamic theories during this process. The results indicate that the matrix was pearlite, and the size of carbides was about 700~800 nm, complex hexagonal M7C3 and cubic M23C6 had the crystallographic orientation relationship of( 112ˉ0)K//( 011ˉ)α, [0001]K//[011]αand(511)K//( 011ˉ)α, [ 116ˉ ]K//[ 011ˉ]α with ferrite respectively. After quenching and tempering, the matrix microstructure was tempered sorbite, and a little of tempered martensite with undissolved carbides. The size of carbides decreased obviously which was about 200 nm. The carbide style transformed to orthorhombic M7C3 and had the crystallographic orientation relationship of( 11ˉ3)K//(200)α、[ 5ˉ12]K//[ 01ˉ1]αwith ferrite. In addition, the ΔH and ΔG of formation and transformation of carbides were both below zero during this process.更多还原