Evaluation Test And The Welding Technology Of SCW550 And Q345B Steels

Increasing pressure of rising prices of raw materials and labor costs,it is more and more serious to the engineering machinery market competition.In this background,the lowest cost of the engineering machinery manufacturing is the biggest pursuit of enterprise of the company.In addition to meet the performance of construction machinery under different conditions and requirements,improve the reliability,give full play to the performance and economically complementary advantages,the welding of dissimilar steel has been widely used in the industry.According to the demands of development and improvement of excavator product,this paper has studied the fabrication weldability and service weldability of SCW550-Q345B dissimilar steel systematically by C02 shielded welding welding test,cast steel SCW550 material weldability test,Q345B material weldability test,Weldment structure test.Also,using the cast steel SCW550 to replace the Q345B material of excavator front-end and rear-end head has been studied.The result reveals that:1.Pure CO2 gas shielded arc welding is unsuitable for SWC550-Q345B dissimilar steel welding,80%Ar +20%CO2 mixed gas shielded arc welding is suitable for SWC550-Q345B dissimilar steel welding;2.Welding SWC550-Q345B dissimilar steel,selecting the?1.2 wire,when welding the bond coat,the best welding current is 220±20A,the best arc voltage is 24±2V;when welding the packed bed and surface coat,the best welding current is 240±20A,the best arc voltage is 26±2V.3.With.the addition of welding heat inputting,the content of Coarse Grain Heat Affected Zone eutectoid ferrite and lath ferrite is increased,reducing joint toughness;As the welding heat inputting increased,the Austenite grain and Widmanstatten is increased,increasing the joint brittleness.4.Preheat reduces the strength of SCW550-Q345B dissimilar weld joint,increasing the width of HAZ width significantly.5.SCW550-Q345B dissimilar steel has good fabrication weldability and service weldability,boasts a fine performance in welding without preheating before welding processing.6.SCW550 steel is able to take the place of Q345B materials as the materials of excavator front-end and rear-end head.It has the prospect of popularization and application on the other models and a new generation of model.