(1) The internal composition of the landscape ingot of weathering steel is seriously segregated, especially the elements of C, S and P. Smelting and ingot casting should be noted.
As a result of the large ingot internal solidification formation crystallisation process is slow, small inclusions ground convergence into naked eye observation visible or ultrasonic for flaw detection of large inclusions. The lower part of the ingot is prone to produce some silicate deposits, in the forging process should remove these deposits.
(2) weathering plate after forging, often can get no uniform, coarse recrystallisation of the organisation grain, austenite grain structure size for generally 3 ~ 4, sometimes even greater. Weather-resistant plate can not be forged in a fire. It needs to be heated several times and forged several times.
Weathering steel landscape production in what need to pay attention to?
Weathering plate products are mainly used for structural parts of Chinese manufacturing enterprises, such as containers, railway vehicles, oil derricks, port buildings, oil companies production management platform development and data from corrosive and chemical media containing sulfur container oil equipment. Due to these characteristics and the effects of segregation and inclusions, the core of the weathered plate should be fully forged, and the forging ratio should be in the range of 2.5 to 4 in order to make the internal structure of the ingot homogeneous, cracking, and welding looseness.
(3) in the process of heating and naturally conducted cooling system, weathering plate inside and outside the temperature difference between the influence of the structure of the thermal stress and the structure of the design of the stress is also larger, may be due to the heating and rapid cooling mode square fa improper treatment and lead to cracking. Due to the large cross-sectional size of hydrogen, it is difficult to escape, so it is necessary to prevent the appearance of white spots.
Weathering plate tempering after rapid cooling also produces residual organisational structure for stress, affecting a great deal. Take 34CrNi3Mo steel with a diameter of 700mn as an example, 650 forging was carried out. For example, in some of the ground for landscape parks, these issues are a red steel floor that can be folded or twisted by depending on the different topography of the enterprise and the surrounding structure, covering the entire social national cultural park with continuous strips.
Therefore, large forgings should be cooled slowly after tempering to reduce residual stresses. Selection of steel for weathering plates should be based on the production of forgings to carry out the size, the performance of the mechanical management system, the use of parts of the network environment and the performance of the process to be fully considered.
