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利用电子金相、定量金相和残留奥氏体含量测定等方法,对低合金高强度结构钢各类淬火组织进行研究。结果表明,在马氏体和贝氏体组织的基体内,都存在着颗粒状或条(片)状岛状组织。岛状组织是含碳量极不相同的富碳合金马氏体和奥氏体或二者的混合物,即所谓(M-A)组织。它的形成,主要是由于原始奥氏体中碳的偏聚和贝氏体转变过程中碳的扩散和富集。(M-A)组织可以分为扩散型、非扩散型和混合型。它们的形态、尺寸和分布,主要根据其所在基体不同而有所差别。三者的本质是一样的。 (M-A)组织在回火时可以发生分解和转变,并具有高于基体组织的回火抗力。低合金高强度结构钢经系列温度回火后,残留奥氏体含量的变化出现马鞍形,主要与(M-A)组织回火分解和转变有关。
Using the methods of electron metallography, quantitative metallography and determination of retained austenite content, various types of low-alloy high-strength structural steel quenched organizations were studied. The results show that in the matrix of martensite and bainite, there are granular or lamellar island-like tissue. Island tissue is a carbon-rich martensite and austenite or a mixture of both, a so-called (M-A) organization. Its formation is mainly due to the segregation of carbon in the original austenite and the carbon diffusion and enrichment during the bainite transformation. (M-A) organizations can be divided into diffuse, non-diffuse and mixed. Their shape, size and distribution, mainly depending on where the substrate is different. The essence of the three is the same. (M-A) The structure can be decomposed and transformed during tempering and have higher tempering resistance than the matrix structure. Low-alloy high-strength structural steel after tempering temperature series, the residual austenite content appears saddle-shaped, mainly with (M-A) tempering decomposition and transformation.