Post-weld heating process to prevent weld seam cracking of high carbon equivalent vacuum extra-thick composite billet

Abstract

The invention relates to a post-welding heating process for preventing a high-carbon equivalent vacuum composite blank welded joint from cracking. The carbon equivalent of an ultra-thick composite blank is 0.6%-1.8% and the thickness is larger than or equal to 500 mm; and the post-welding heating process comprises the following steps that 1) after being welded by a vacuum electron beam, the ultra-thick composite blank is continued to be slowly cooled in a vacuum chamber for 1-3 hours, and then a vacuum is broken; 2), the composite blank is conveyed to a resistance heating furnace for being heated by sections; and 3), the composite blank enters a chamber furnace for being heated, a layer of plain carbon steel cold-rolled sheet is covered on the upper surface of the composite blank before the composite blank enters the chamber furnace, and the composite blank is heated through a sectional heating mode. According to the process, after being welded by the vacuum electron beam, the composite blank is slowly cooled and heated by multiple stages, so that the situation that cracks are generated in the rolling process due to the fact that the composite blank is directly fed into the furnaceafter being welded is avoided.

Description

technical field [0001] The invention relates to the technical field of metal composite plate production, in particular to a post-weld heating process for preventing weld seam cracking of a high-carbon equivalent vacuum extra-thick composite billet. Background technique [0002] High carbon equivalent steel is very sensitive to the formation of cold cracks due to its greater tendency to harden and form high carbon martensite. At the same time, the martensite structure formed in the heat-affected zone of welding is hard and brittle, resulting in a great decrease in the plasticity and toughness of the joint. Therefore, the weldability of high carbon equivalent steel is extremely poor, and hot cracks and cold cracks are prone to occur during welding. [0003] The current common practice of high carbon steel welding is preheating before welding and heat preservation after welding. These methods are relatively easy to realize under conventional welding conditions, but they are ra...

AI Technical Summary

Problems solved by technology

[0005] The vacuum chamber electron beam welding equipment does not have a heating function. Previously, there were public documents that proposed to use pre-weld preheating to avoid welding cracks. However, practice has proved that pre-weld preheating alone cannot meet the production requirements of high-carbon steel clad plates. Requirements, although it avoids cracks in the welding process, cracking will still occur in the heating and rolling process