Heat Treatment Methods for Straight Seam Steel Pipes

Steel pipes with welds parallel to the longitudinal direction of the pipe are known as straight seam steel pipes. Their production process is simple, efficient, and cost-effective, resulting in rapid growth. Heat treatment methods for straight seam steel pipes include: The mold layout should be rational, with minimal thickness and symmetrical shape. For molds with significant deformation, deformation rules should be understood, and machining allowances should be made. For delicate and complex molds, preheating, aging, tempering, and nitriding treatments can be used to control mold precision. When repairing mold defects such as pinholes, pores, and wear, use cold welding machines or other repair equipment with minimal thermal shock to avoid deformation during the repair process. Preheating delicate and complex molds should eliminate residual stresses from machining. For delicate and complex molds, if conditions permit, vacuum quenching should be attempted, followed by a low-temperature treatment. While ensuring mold hardness, precooling, staged cooling, or warm quenching should be attempted. Appropriate material selection is crucial. For delicate and complex molds, select low-deformation mold steel with good raw material quality. Die steel with severe carbide segregation should undergo proper casting and tempering heat treatment.

In the early days of the steel pipe industry, there were many deceptive practices, but now that people are more proficient in the industry, these tactics can be identified with the naked eye.

1. If the wall thickness of the steel pipe is insufficient, the gate method will be used. The end of the steel pipe will appear thicker with a hammer shield, but the original shape can be revealed by measuring with an instrument.

2. Straight seam steel pipe is used as a seamless steel pipe. The number of straight seam welds is less than one longitudinal weld. The entire steel pipe is polished using a machine commonly called a polishing process, giving the appearance of seamless seams.

3. A more complex method is now available for seamless steel pipe, which is also a heat-expanded steel pipe. After expansion, lead powder is visible on the inside, and burn marks are visible on the outside. The weld is also invisible.

4. Girth-welded straight seam steel pipe uses polishing to replace seamless steel pipe.