The adjacent plates of the HBR series heat exchanger are stacked at an angle of 180 degrees and welded together to form a single unit. Heat exchange between hot and cold fluids occurs on both sides of each plate. The fully welded heat exchanger is constructed using argon arc welding without any seals. The main component for heat exchange, the plate bundle, is entirely welded using the same welding material as the plate material, eliminating the need for any additional sealing elements between the plate channels. This design not only ensures high heat transfer efficiency similar to that of detachable plate heat exchangers but also allows the heat exchanger to operate in conditions with a medium temperature of ≤400°C and pressure of ≤3.0 MPa. The absence of non-metallic, elastic sealing materials broadens the range of compatible working media, extends the safety usage period, and reduces maintenance costs. The plates are made of stainless steel, titanium, and other materials, molded through a unique process to achieve a smooth surface. Combined with specific flow channels, this design minimizes scaling tendencies on the working surface and facilitates easy cleaning. To meet various user requirements, the aspect ratio of the heat exchange plates can be determined through optimized design.