Rebar is widely used in building materials, and it is in significant demand [
1,
2,
3]. In 2021, the world’s total steel output reached 1.951 billion tons, of which rebar accounted for approximately 18% [
4]. Ordinary rebars are prone to corrosion and expansion. Therefore, concrete structures can be damaged, and building life is severely reduced when the volume increases beyond the elastic limit of concrete [
5,
6,
7]. In addition, roads must be maintained, which has high costs. For example, according to the Federal Highway Administration, road maintenance costs more than USD 20 billion per year in the United States of America, and the annual maintenance cost for bridges in Germany is in the range of EUR 6–30 billion [
8]. In order to effectively improve the safety performance and service life of roads, bridges, and important buildings, two methods have been used that prevent and delay the corrosion of reinforcing bars in such structures. The protective ability of building structures can first be improved by increasing the thickness of the concrete. However, this method significantly increases the cost of the concrete structures [
9]. Protective layers have also been added to the surface of rebar by spraying epoxy resin powder or zinc plating, for example. However, the coatings are prone to damage and corrosion during transportation and construction [
10,
11,
12,
13]. Clad rebars use two different metal-rolled composite compositions. The rebar outer layer is composed of stainless steel, which has very high corrosion resistance, while the base metal is carbon steel, which meets the relevant mechanical property requirements. In addition, clad rebar has a lower price than stainless rebar. Several studies have been conducted on the optimization of the rolling process and the preparation technology for clad rebars. For instance, Szota et al. [
14] established the constitutive equation for the inner and outer layers of C45/306L rebar based on the Tresca yield criterion, and a numerical simulation of the finished hole and non-finished hole was conducted using Forge2005 software (Material Forming Research Center, Paris, France). The results showed that the thickness distribution of the steel cladding rolled with the flat elliptical pass was more uniform than that of the single-radius and multi-radius ellipses. Sawicki et al. [
15,
16] placed stainless steel rods below the non-melting electrode and used tungsten inert gas-shielded welding to generate the high temperature needed to melt the stainless steel rods and spray onto the carbon steel surface. However, this process was limited by certain issues, such as the uneven distribution of the stainless steel cladding and the difficulty of engaging the rolling mill. Feng et al. [
17] used a thermal simulator to prepare 20MnSi/306L rebars with different compression temperatures (950 °C and 1050 °C) and compression rates (50% and 70%). When the compression rate increased from 50% to 70%, the number of oxides on the composite interface significantly decreased, the grains became continuously thinner, and the tensile strength of the rebar increased from 589 MPa to 690 MPa. When the compression temperature increased, significant amounts of C elements crossed the composite interface to reach the stainless-steel side and reacted with Cr to produce carbon–chromium compounds, which resulted in an increase in the hardness value of the stainless steel near the composite interface. All these findings were based on thermal simulators, and whether they can guide industrial production should be verified. The American company STELAX recycled wasted iron scraps and fused them into rod shapes. They were then placed into a stainless steel pipe, which was subsequently sealed at the end face and then rolled. The South Dakota Department of Transport deduced from the performance test of its product that there were large holes between the clad and the base, which indicated that the iron scraps and stainless steel pipe could not undergo effective bonding during the hot rolling [
18]. Pak et al. [
19] used electroslag welding technology to prepare a composite billet of rebar. Stainless steel powder was first placed on the surface of the carbon steel. Resistance heat generated by the slag was then used to melt the stainless steel powder to form a preliminary bond between the stainless steel and carbon steel. However, the production efficiency of the assembly process was low, and significant amounts of impurities were present in the composite interface of the blank. Liu et al. [
20] used a flux deposition process to prepare a 20MnSiV/Cr13 composite billet. The 20MnSiV surface was first polished. The Cr13 stainless steel was then heated until liquefaction. Afterwards, the Cr13 was sprayed onto the carbon steel surface using a special nozzle. Although this process effectively solved the interface oxidation problem affecting the billet during the heating and rolling, the operation is more complicated, and it is still in the laboratory stage. Xie et al. [
21] first pulled a carbon steel rod and stainless steel pipe so that the inner and outer layers of the metal produced a certain pretension force, and the billet was then sealed and rolled with six passes. The experiment results showed that the clad of the cladded rebar was evenly distributed, with all the mechanical properties meeting the relevant requirements. However, this process requires a pulling process and supporting facilities to be added in the existing rebar production line, which reduces the production efficiency. Our team successfully rolled out 20MnSiV/316L rebar in Liuzhou Iron and Steel Plant with vacuum-hot-rolling technology in 2021. Through testing, it was found that the tensile properties, bonding properties, and bending properties of the 20MnSiV/316L rebar met the CNS GB/T 36707-2018 standard, and it was close to 316L stainless steel in terms of its corrosion-resistance properties, which is ten times as high as carbon rebar [
22].
This paper presents a preparation method for 55#/316L rebar that can be used to simplify the preparation process while guaranteeing the properties of the clad rebar, as well as providing experience and a reference to help scholars select materials for the inner and outer layers of rebar. This process involves inserting the carbon steel after surface treatment into a stainless steel pipe. Welding and sealing are then performed and, finally, hot rolling is conducted for shaping. In 2021, the as-produced clad rebars were successfully applied in the construction of the Quanhe Bridge in Linquan, which was the first application of its kind in China.