Research on Welding Process of Alloy Cast Steel and High Strength Wear-resistant Steel

    
    Abstract
    
    This paper mainly introduces the welding process, select of welding process, parameters, precautions and other related knowledge of alloy cast steel and high-strength wear-resistant steel. Alloy cast steel generally refers to cast steel with alloy elements added to engineering carbon steel. The high strength wear-resistant steel is made of high-strength steel, medium carbon alloy steel and special alloy by reasonable heat treatment and reasonable combination of chemical elements. The welding method of high-strength wear-resistant steel has higher demands on welding parameters, welding process, welding materials and other aspects, and the welding process is more complicated. The selection of welding process, welding parameters, precautions and other knowledge are introduced in detail in this paper. At the same time, a lot of data supporting drawings are used to illustrate.
    
    1. Introduction
    
    Alloy cast steel is a cast steel added with alloy elements such as manganese, chromium, molybdenum, vanadium, niobium, titanium and copper during smelting. The high strength wear-resistant steel is produced by reasonable heat treatment and reasonable combination of chemical elements. According to the different proportion of alloy elements, it can be divided into three ways: low-alloy steel, medium-alloy steel and high-alloy steel. In the process of melt metallurgy, the volume fraction of alloy elements will reach 0.2% ~ 3% in the matrix. Due to the higher hardness, higher yield strength and good impact toughness, high-strength wear-resistant steels can be used for making machinery parts with strong impacts, such as blades and lining plates in many machinery and equipment.
    
    2. Selection of Welding Process
    
    Due to the complexity of high-strength wear-resistant steel and the high requirements of welding process and welding parameters, before welding, the welding process of high-strength wear-resistant steel needs to be reasonably selected according to the material, shape, size and condition of parts, so as to ensure the weld quality. The common welding process includes manual arc welding, gas shielded welding, submerged arc welding and electroslag welding.
    
    For the welding of alloyed cast steel, manual arc welding should be used as far as possible, the specific welding method is manual shielded arc welding, and the welding material is low hydrogen welding rod series of welding wire. The welding speed should be relatively fast, but the heat input should be reduced as far as possible to reduce the thermal stress impact on the heat affected zone.
    
    3. Welding Parameters
    
    In order to ensure the welding quality of alloy cast steel and high strength wear-resistant steel, the welding parameters should be selected reasonably.
    
    1. For the manual shielded arc welding of alloy cast steel, the welding current is preferably in the range of 70 ~ 110A, the welding speed is in the range of 30 ~ 50 cm/min and the welding size is 3.2 ~ 4.0mm.
    
    2. In the welding of high-strength wear-resistant steel, the welding current of manual arc welding is selected in the range of 70 ~ 110A, and the welding speed is in the range of 10 ~ 15 cm/min. The size of the welding wire is selected in the range of 2.8 ~ 3.2mm.
    
    3. For gas shielded welding, the welding current is selected in the range of 130 ~ 160A, the welding wire size is selected in the range of 2.8 ~ 3.2mm, and the welding speed is selected in the range of 25 ~ 40 cm/min. The heat input is preferably not more than 15KJ/mm.
    
    4. For submerged arc welding, the welding current is selected in the range of 200 ~ 250A, the welding wire size is selected in the range of 4.0 ~ 5.0mm, and the welding speed is selected in the range of 30 ~ 60 cm/min. The heat input is preferably not more than 20KJ/mm.
    
    4.Precautions
    
    1. The preparation of welding should be in strict accordance with the welding process before welding, paying attention to the tempering treatment and the selection of welding materials.
    
    2. The welding process should be controlled strictly during welding, paying attention to the control of welding speed and arc voltage, and avoiding excessive current.
    
    3. The welding shall meet the technical requirements of the pressure vessel design specification, and the temperature of the heat affected zone shall be checked at intervals to ensure that the temperature does not exceed the specified value.
    
    4. Strict inspection and control should be carried out after welding, and qualified welds should be inspected according to relevant standards to ensure quality.
    
    5. Conclusion
    
    The welding of high strength wear-resistant steel needs to select the welding process, parameters, and necessary precautions, and we should strictly carry out according to the design requirements and the relevant standards for welding, so as to ensure the quality of welding. In addition, different welding processes have different welding requirements, precision, welding speed and other parameters, so it is necessary to pay attention to control, firmly grasp the welding of alloy cast steel and high strength wear-resistant steel.

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