Copyright Goodheart-Willcox Co., Inc. 127 Objectives After completing this chapter, you will be able to: ❑ Identify types and grades of steel and steel alloys. ❑ Identify shapes and forms of steel and steel alloys. ❑ Select the appropriate steel filler metal based on the steel to be welded. ❑ Explain joint preparation, weld backing, and preheating for steels. ❑ Recall welding procedures and techniques for welding steel using DCEN. ❑ Recall correct torch positioning for various types of welds. ❑ Differentiate between stringer beads and weave beads. ❑ Recognize groove and fillet weld defects. ❑ Recall factors that influence postweld treatment. Key Terms Introduction The GTAW technique required for a given job depends on many factors, including the weld joint design. Welders must constantly monitor and adjust many critical variables in order to produce a high- quality weld. The effects of these variables can be seen in the behavior of the weld pool as the weld is being made. Welding skill is acquired by practice, practice, and more practice. Changing one variable at a time is the best way to determine what the weld needs. The following questions should be considered when practicing welding: • Is the weld the right size? • Is the weld too high or too low? • Is the proper travel speed being used? • Is the torch angle correct? • Is the welding rod being held at the proper angle? • Is the weld pool fl owing properly? • Is the current (amperage) correct? • Is the voltage (arc length) correct? • Is the weld in the proper location? • Is the fi llet weld leg the proper size? Also, it is important to remember to fi ll the crater at the end of the weld and hold the torch over the end of the weld until it cools. This allows the postfl ow of shielding gas to protect the hot metal. Chapter 8 Manual Welding Techniques annealing casting chromium-molybdenum steels forging heat treating martensite quenching stringer bead tempering travel angle walking (rocking) the cup weave bead wetted work angle