回火温度对铬镍合金结构钢组织性能的影响

利用SEM、TEM手段研究了不同回火温度对铬镍合金结构钢组织性能影响。结果表明:随回火温度的升高,试验钢的硬度、强度呈下降趋势;塑性、韧性先下降,随后出现缓慢上升平台,最后迅速提高;低温下剪切唇主要为韧窝状,有的韧窝较大且较浅,断口心部呈现准解理断裂特征,随回火温度升高,心部的韧窝数量随之增加;淬火后,200 ℃回火组织为合金渗碳体尺寸细小、板条界面清晰的回火马氏体,400 ℃回火组织为合金渗碳体呈杆状、界面较模糊的回火托氏体,600 ℃回火组织为合金渗碳体呈球状、无板条状特征的回火索氏体。

Effect of tempering temperature on microstructure and properties of Cr-Ni alloy structural steel

Microstructures and mechanical properties of Cr-Ni alloy structural steel under different tempering temperatures were studied by means of tensile tester, impact tester, hardness tester, metallographic microscope, scanning electron microscope, transmission electron microscopy and other equipments. The results show that the hardness and strength of the tested steel decline, plasticity and toughness decrease at first, then show a curve platform rising slowly and increase linearly at last with the increase of tempering temperatures. Under lower temperature the shear lip is composed of dimples, some of them are big and shallow. The core parts are quasi-cleavage fracture. The quantity of dimples increases with the rising of tempering temperatures. After quenching and tempering at 200 ℃, the microstructure is tempered martensite with small amount of carbide and clear lath boundaries, when tempered at 400 ℃, the microstructure is tempered troostite with rod carbide and fuzzy boundaries, and when tempered at 600 ℃, the microstructure is tempered sorbite with globular carbide and no lath boundaries.