Welding of dissimilar materials in the sintering machine cylinder
July 17 13:06:41, 2025
Problem Raised
In our company, we often encounter welding parts made from special materials. One common example is the cylinder shown in the drawing. Normally, it should be a one-piece structure, but it's designed to be a welded assembly consisting of a 40Cr cylinder and a 20 Steel grease nipple. From a welding perspective, this design isn't ideal. However, the designer opted for this approach to reduce costs, as the two materials have very different properties and are difficult to weld together.
Welding these dissimilar materials requires a lot of extra work, such as preheating before welding and post-weld heat treatment. These steps not only extend the production cycle but also negatively affect the surface quality of the final product. The challenge lies in balancing cost, performance, and quality, which has led us to seek a better solution.
Workpiece
2. Solution
Previously, when dealing with similar material welding issues, we used J507 electrodes, and skilled workers were quite familiar with the process. Preheating and post-weld heat treatment were always necessary to prevent delayed cracking. However, we recently decided to switch to A307 stainless steel electrodes.
Although theory suggests that stainless steel welding rods are suitable for welding dissimilar materials, the specific choice depends on detailed analysis and practical experience. After evaluating the properties of the electrode and considering past experiences, we finally chose A307. This rod has a tensile strength of around 550MPa, making it well-suited for welding 40Cr and 20 Steel.
3. Specific Implementation and Results
We decided to use φ4mm A307 stainless steel electrodes. Before welding, they were baked at 250°C for 1 hour. Unlike previous methods, there was no need for preheating. We simply cleaned the joint area with acetone, and no heat treatment was required after welding. The welding current was set to 140A, using direct current reverse polarity (DCRP).
The results were very promising. The cylinders welded with A307 electrodes met all quality requirements, passed inspection smoothly, and significantly improved production efficiency. This new method has opened up a fresh approach for welding dissimilar materials within our company, proving that with the right materials and techniques, even complex challenges can be overcome effectively.
