The load-bearing beam is one of the main parts of the automobile, which is directly related to the load, service life, mechanical performance and safety of the vehicle. At present, most of the domestic special vehicle bearing beams are welded by steel plates, and the developed countries have widely used hot-rolled H-type wear-resistant steel plates as large beam steel. Compared with the traditional welded girder, the hot rolled H-type wear-resistant steel plate bearing girder has obvious advantages. Replacing traditional welded steel beams with hot-rolled H-shaped wear-resistant steel plates has good economic and social benefits, involving the following processes:
1. Composition design
Special vehicle bearing beam steel in the process of driving by a variety of impact, torsion and other complex stress, its manufacturing materials not only need to have a high strength, but also require good plasticity, toughness, so in the composition design, as far as possible to control C, Mn fluctuations in a small range, while reducing the content of P, S in steel. The composition is: C: 0.14-0.18; Mn: 1.4-1.5; Si: 0.20-0.40; V: 0.015-0.025; S≤0.020; P≤0.025.
2. Smelting process
According to product requirements, steel grade and internal control composition range are designed, and composition is fine-tuned through off-furnace refining. Qualified casting billets are produced by advanced technology such as continuous casting without oxidation protection. The smelting process is as follows: hot metal pretreatment → converter smelting →LF refining → continuous casting. The continuous casting billet is 240×375 specifications.
3. Rolling process
The hot rolled H-type wear-resistant steel plate has the characteristics of small total reduction ratio, large temperature difference in the rolling length direction, and different properties of the product section. Therefore, to ensure that the product has a stable and uniform performance, rolling process control is particularly important.
1) The heating temperature is 1080-1280℃, and the soaking temperature is 1080-1280℃; The furnace time is 120-210min.
2) The total deformation in the BD zone during the rolling process is controlled at about 30%, so that the steel grains in the recrystallization zone are preliminarily refined, and the rolling deformation in the finishing rolling zone is ensured to reach more than 45% ~ 70%, and the pass reduction rate is increased as much as possible. Rolling size is H196×149.
Special vehicles refer to vehicles for special purposes that exceed the limits of design vehicles in terms of size, weight, etc. There are many special car production plants in China, and the demand is large. Replacing the traditional welded steel beam with hot-rolled H-type wear-resistant steel plate is a development trend of future special truck bearing beam steel, and the market prospect is very broad.
