A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Influence of nonmetallic inclusions on the resistance of metal weld to brittle fractures
According to statistics, up to 80% of all fixed metal structure accidents are associated with welded joints. However, most of the emergency destructions, usually caused by non-metallic inclusions in the weld metal, are fragile. The probability of brittle fracture decreases with increasing plasticity. And plasticity, that depends on the mobility of dislocations to a great degree, decreases with temperature decrease and increase in the strain rate. The plasticity of the metal is a structurally sensitive property and depends on the type of crystal lattice that determines the number of densely packed directions and slip planes. Low-alloy steels, mainly used in welded steel structures, have a volume-centered cubic lattice with a relatively small number of planes and sliding direction. These steels are ductile at relatively high temperatures and become brittle at negative temperatures. The only way to improve the ductility of the metal without significantly reducing its strength is to grind grain. One of the effective ways to obtain finegrained structure of the weld metal is to introduce modifiers into the weld pool. The modifiers should be in the form of refractory compounds (oxides, carbides, nitrides), which in the crystallization zone of the weld pool are crystallization centers and increase the number of grains per unit volume. Studies of the modification of the crystallizing metal in the conditions of casting and fusion welding have shown that the melt overheating reduces the effect of modification. In electric arc welding with an arc temperature of more than 6000K, the danger of deactivation of the modifier is high. One way to reduce overheating and improve the efficiency of modifiers in welding is the introduction of modifying particles in the weld pool in combination with more massive granules in the form of chopped wire, serving as micro-refrigerators. This method, called welding with a metalchemical additive (MCA), is successfully used in bridge construction. Modification of the weld pool with refractory particles, along with the positive effect of grinding grain in the weld there is also a negative moment: modifying particles that remain in the weld in the form of non-metallic inclusions are stress concentrators and can become centers of cracking
Influence of nonmetallic inclusions on the resistance of metal weld to brittle fractures
According to statistics, up to 80% of all fixed metal structure accidents are associated with welded joints. However, most of the emergency destructions, usually caused by non-metallic inclusions in the weld metal, are fragile. The probability of brittle fracture decreases with increasing plasticity. And plasticity, that depends on the mobility of dislocations to a great degree, decreases with temperature decrease and increase in the strain rate. The plasticity of the metal is a structurally sensitive property and depends on the type of crystal lattice that determines the number of densely packed directions and slip planes. Low-alloy steels, mainly used in welded steel structures, have a volume-centered cubic lattice with a relatively small number of planes and sliding direction. These steels are ductile at relatively high temperatures and become brittle at negative temperatures. The only way to improve the ductility of the metal without significantly reducing its strength is to grind grain. One of the effective ways to obtain finegrained structure of the weld metal is to introduce modifiers into the weld pool. The modifiers should be in the form of refractory compounds (oxides, carbides, nitrides), which in the crystallization zone of the weld pool are crystallization centers and increase the number of grains per unit volume. Studies of the modification of the crystallizing metal in the conditions of casting and fusion welding have shown that the melt overheating reduces the effect of modification. In electric arc welding with an arc temperature of more than 6000K, the danger of deactivation of the modifier is high. One way to reduce overheating and improve the efficiency of modifiers in welding is the introduction of modifying particles in the weld pool in combination with more massive granules in the form of chopped wire, serving as micro-refrigerators. This method, called welding with a metalchemical additive (MCA), is successfully used in bridge construction. Modification of the weld pool with refractory particles, along with the positive effect of grinding grain in the weld there is also a negative moment: modifying particles that remain in the weld in the form of non-metallic inclusions are stress concentrators and can become centers of cracking
Influence of nonmetallic inclusions on the resistance of metal weld to brittle fractures
BOLDYREV Alexander Mikhaylovich (author) / ORLOV Alexander Semenovich (author) / GUSCHIN Dmitry Alexandrovich (author) / RUBTSOVA Elena Grigorievna (author) / SANNIKOV Vladimir Gennadievich (author)
2018
Article (Journal)
Electronic Resource
Unknown
Metadata by DOAJ is licensed under CC BY-SA 1.0
Nonmetallic phosphorus inclusions in steel
| Engineering Index Backfile | 1961
Nonmetallic phosphorus inclusions in steel
| Engineering Index Backfile | 1961
Influence of nonmetallic inclusions on the fatigue strength of metals
| British Library Online Contents | 2007
A modified size effect model for brittle nonmetallic materials
| British Library Online Contents | 2002
Nonmetallic inclusions in rails with various methods of deoxidation
| Engineering Index Backfile | 1965