15CrMo seamless steel tube and carbon plate welding fracture what is the reason?
Welding stress should be too concentrated, 15CrMo material is very brittle after quenching, when welding local high temperature, and then no corresponding insulation measures, lead to fracture.Welding: welding, can also be written as "welding" or welding, melt, is two or more than two kinds of material (homogeneous or heterogeneous) by heating and pressurizing, or both, so that the two parts produce atomic binding processing and connection mode. Welding is widely used, both for metals and for metals. Welding is the process of welding the workpiece interface to the molten state, without pressure to complete the welding process. When welding, the heat source rapidly melts and melts at the interface of the two workpiece to be welded to form a molten pool. The molten pool moves along with the heat source, and a continuous weld seam is formed after cooling, and the two workpieces are connected into a whole.
That's the problem of too much stress in the welding! 15CrMo material after quenching is very brittle, local high temperature welding, then there is no insulation measures, fast cooling speed caused by the welding part of a slight quenching appear, so the stress concentration caused by cold cracking!It is recommended that the 15CrMo pipe be heated to 150 degrees before welding! Pay attention to heat preservation after welding!If the heat treatment process needs to be welded, the heating rate is 200 degrees /h, rise to 715, holding 1 hours and 15 minutes, the cooling rate is 100 degrees /h, and the air cooling is down to 300 degrees centigrade.
Possible causes:1. the choice of welding material must be high strength than carbon plate, plastic is better than 15CrMo. Selection may not be based on the welding principle of heterogeneous steel for material selection.2. there is no proper welding procedure.2. preheating is not enough before welding.
The steel body may suddenly cool significantly high temperature processing have occurred that situation I experience after I put the steel body warmed a bit in the process you can try to fix if you can not in the upstream steel,,
Is heat-resistant steel, welding performance is poor, using ER80S-B2L welding wire, T1G welding bottoming, E309Mo-16 welding rod, electrode filling arc welding cover surface, welding without heat treatment
