The difference between application of 20# steel and Q345 steel. 20# steel is mainly used for making parts, which can be heat treated; Q345 steel is mainly used for making engineering structural parts, which is usually not heat treated. Q345 steel does not emphasize the composition, but its yield strength must be above 345mpa. Because the composition A709 grade HPS50W bridge steel plate is not fixed, Q345 steel is difficult to heat treatment (the temperature and time control of heat treatment are related to the composition, and different components use different processes).
The hardness of the steel plate is very high, so special equipment is needed to complete the processing and cutting of these materials, A709 grade HPS50W bridge steel plate. In order to cut the plate into an ideal size, the steel plate cutting needs to use natural gas flame for preheating, which will generate a large amount of oxygen flow during the operation. These substances will oxidize the steel plate, and then form a cutting edge, then the cutting operation process is basically completed. In the actual processing work, there are many different classifications for steel plate cutting.
Try to use A709 grade HPS50W bridge steel plate high-quality alkaline covered electrode as much as possible, and don't use inferior electrode to save money. According to the theory of chromium poor, chromium carbide will be precipitated on the upper edge of the grain boundary of the weld and heat affected zone when the A709 grade HPS50W bridge steel plate temperature range is between 450 ℃ and 850 ℃, resulting in chromium poor grain boundary, which is insufficient to resist corrosion.
The production process of hot-rolled steel plate and cold-rolled steel plate is different. Hot rolled steel plate is rolled at high temperature, and cold rolled steel plate is rolled at normal temperature. Generally speaking, cold rolled steel plate has better strength and hot rolled steel plate has better ductility. The thickness of A709 grade HPS50W bridge steel plate cold rolling is generally smaller, and that of hot rolling can be larger. The surface quality, appearance and dimension accuracy of cold rolled steel plate are better than that of hot rolled steel plate.
