Embodiments disclosed herein relate to a large vacuum chamber body that has been welded together. The chamber body may have a high emissivity coating on at least one surface therein. Due to the large size of the chamber body, the chamber body may be formed by welding several pieces together rather than forging the body from a single piece of metal. The pieces may be welded together at a location spaced from the corner of the body, which may be under the greatest stress during evacuation, to ensure that the weld, which may be the weakest point in the body, does not fail. At least one surface of the chamber body may be coated with a high emissivity coating to aid in heat transfer from incoming, heated substrates. The high emissivity coating may increase substrate throughput by lowering the time that may be needed to reduce the substrate temperature.