Research on the Effect of Preheating Temperature on the Microstructure and Mechanical Properties of the Heat Affected Zone of Q960E Steel
The welding heat-affected zone of high-strength steel Q960E used in engineering machinery has welding problems such as embrittlement and softening.To solve this problem,the welding thermal simulation technology was adopted,different preheating temperatures and heat inputs were set,the welding heat-affected zone was obtained,and the effects of preheating temperature and heat inputs on the microstructure and mechanical properties of the welding heat-affected zone were explored through microstructure analysis and mechanical property testing.The results indicate that the microstructure of the welding heat-affected zone of Q960E steel is mainly composed of low-carbon martensite and bainite.As the preheating temperature increases,the content of bainite increases and granular bainite brittle structure begins to appear.The tensile strength of the welding heat-affected zone slightly decreases with the increase of preheating temperature.The preheating temperature has little effect on the microhardness of the welding heat-affected zone.The low-temperature impact toughness first increases and then decreases with the increase of preheating temperature.Under experimental conditions,the best comprehensive mechanical properties of the welding heat affected zone microstructure were obtained when the welding line energy was 1.5 kJ/mm and the preheating temperature was 150℃.
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