【摘要】 本文利用透射电子显微相和电子衍射相测定了18Ni(250)马氏体时效钢的焊缝组织。利用数个不同晶带的衍射相,鉴别了金相中沿柱状晶界析出的白色块状物即逆转变奥氏体。试验表明,焊缝组织的不均匀性,特别是块状逆转变奥氏体,和在晶界、晶内局部区域密集分布的脆性相,是使焊缝韧性低于母材的主要原因。并据此提出了改善焊缝韧性的途径。更多还原

【Abstract】 The structure of weld metal of 18Ni(250) maraging steel is studied under transmission electronmicroscope and by electron diffraction method. Using diffraction patterns of various crystal zones,the white blocky structure, precipited along the interface of columnar crystals in the microstructurewas identified as reverse transformation austenite. It is proved that the heterogenity of weld structure,especially blocky reverse transformation austenite and dispersive brittle phase at grain boundariesand within the grains are the main causes which bring the fracture toughness of the weld metallower than that of the parent metals. Methods to improve the toughness of weld metal are suggested.更多还原