石油化工用Hastelloy C276焊接接头组织特征及性能

MICROSTRUCTURE AND PROPERTIES OF HASTELLOY C276 WELD JOINTS FOR PETROCHEMICAL INDUSTRY

文章采用OM、SEM等方法对C276合金激光焊接头的组织和性能展开了工艺研究。研究表明:该合金焊缝组织为奥氏体,其形貌与热输入密切相关;热影响区由长大粗化的等轴奥氏体晶粒和晶界析出物组成。对比4种参数的焊缝组织,发现热输入为30J/mm的焊缝为细小奥氏体等轴晶和胞晶,随着热输入增加,焊缝中奥氏体逐渐转变为柱状晶。力学性能测试表明,焊缝为接头力学性能薄弱区域,焊缝强度、硬度和延伸率随热输入增加而降低。电化学测试表明,酸性环境的焊缝耐蚀性弱于母材的,且热输入越大,焊缝的耐蚀性越差。采用低热输入30J/mm焊接的接头具有良好的塑性、强度和硬度配合,以及良好的耐蚀性。

This paper adopts OM and SEM methods to carry out process research on the microstructure and properties of laser weld joints of C276 alloy.The research indicates that the weld of this alloy consists of austenite,and its morphology is closely related to heat input.The heat affected zone(HAZ)is composed of coarsened equiaxed austenite grains and precipitates along grain boundary.Comparing the microstructure of weld joints with four different parameters,it is found that the weld with heat input of 30 J/mm is composed of fine equiaxed crystal and cell crystal austenite.With increasing heat input,the morphology of austenite is gradually transformed into columnar crystal.The mechanical properties tests show that weld is the weak area in joint.The strength,hardness and elongation of welding decrease with the increase of heat input.The electrochemical test shows that in simulated acid environment,the corrosion resistance of the weld is weaker than that of the base metal;and the larger the heat input,the worse the corrosion resistance of the weld.This indicates that the joint with low heat input of 30 J/mm has good combination of plasticity,strength and hardness,and good corrosion resistance.