A welding method for ultra-fine grain steel ss400 medium and thick plates
A welding method and ultra-fine grain technology, applied in welding equipment, welding accessories, arc welding equipment, etc., can solve the problems of poor stability of mechanical properties of welded joints, and achieve control of abnormal growth of austenite grains and structure deterioration, The effect of improving welding production efficiency and reducing the probability of occurrence
Active Publication Date: 2017-05-03
INNER MONGOLIA UNIV OF SCI & TECH
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[0004] In order to reduce the disadvantages that the existing welding process of ultra-fine grain steel SS400 tends to produce coarse structure in the overheated zone, increase in the width of the heat-affected zone, and the formation of the joint softening zone, resulting in poor stability of the mechanical properties of the welded joint, the present invention provides an improved ultra-fine grained steel SS400. A welding method for ultra-fine grain steel SS400 medium and thick plates, which reduces the width of the heat-affected zone and avoids the formation of the softening zone, and improves the uniformity of the mechanical properties of the microstructure around the weld.
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[0026] Weak links of the ultra-fine grain steel SS400X-groove welding of the present invention are mainly concentrated near the heat-affected zone, where hardened structures and softened zones with low plasticity and high hardness are likely to be produced. Therefore, the width of the heat-affected zone directly affects the performance of the welded joint. The experimental research shows that the grains of the original austenite structure in the superheated zone grow seriously with the increase of heat input, and some widmanstatte structures grow along the grain boundaries obviously. At the same time, the nucleation rate of the fully normalized zone and the incompletely normalized zone prone to softening phenomenon are accelerated, and the width of the zone is increased, resulting in an overall increase in the width of the heat-affected zone. According to the present invention, the optimum heat input range for keeping the width of the heat-affected zone narrow is: Figure 2(a...
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Abstract
The invention relates to a welding method for SS400 ultra-fine grained steel medium plates and belongs to the field of metal welding. According to the method, an X-shaped groove is formed between the SS400 ultra-fine grained steel medium plates, a weldment is preheated through flames at 100 DEG C, and the interlayer temperature ranges from 100 to 150 DEG C. The first welding heat input is controlled within a range from twelve kJ / cm to seventeen kJ / cm. The second welding heat input is controlled within a range from ten kJ / cm to twenty-two kJ / cm. After slag removal is carried out on welding joints, two layers of annealing welding beads are added to the obverse welding joint and the reverse welding joint respectively. Through the welding method for the SS400 ultra-fine grained steel medium plates, the breadth of a heat affected zone of SS400 ultra-fine grained steel is substantially reduced, abnormal growth and texture deterioration of austenite grains in a coarse grained region are effectively controlled, the probability of appearance of a softening zone is reduced, the nonuniformity of welding stress is reduced, and deformation is reduced.
Description
technical field [0001] The invention relates to a method for welding medium and thick plates of ultra-fine grain steel SS400, which belongs to the field of metal welding. Background technique [0002] Ultra-fine grain steel SS400 is the most commonly used steel grade in the Japanese Industrial Standard "Rolled Steel for Ordinary Structures" standard JISG3101-2004, and its maximum tensile strength reaches 400MPa. Ultra-fine grain steel SS400 has the characteristics of ultra-fine grain, ultra-purity and excellent comprehensive performance. It is widely used in general structural steel used in bridges, ships, vehicles and other structures. Since no alloy elements are added in the production process, the production cost It is greatly reduced, while the strength and toughness are doubled compared with commonly used steel with the same composition. [0003] However, affected by the welding heat cycle during the welding process of ultra-fine grain steel SS400, the original austeni...
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IPC IPC(8): B23K9/00
CPCB23K9/167B23K9/23B23K9/235B23K9/32B23K2101/18
Inventor 白庆伟麻永林邢淑清陈重毅
Owner INNER MONGOLIA UNIV OF SCI & TECH