Welding of dissimilar materials in the sintering machine cylinder
July 17 14:06:17, 2025
Problem Raised
In our company's welding parts, we often encounter components made from special materials. The cylinder shown in the drawing is a common part, but instead of being a single-piece structure, it was 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. Traditional welding methods require extensive preparation, such as preheating before welding and post-weld heat treatment, which increases production time and negatively affects the surface finish of the final product.
Workpiece
2. Solution
Previously, when dealing with dissimilar material welding, we used J507 electrodes, and experienced welders were quite skilled at handling them. However, this process required preheating and post-weld heat treatment to prevent delayed cracking. Now, we've decided to switch to A307 stainless steel electrodes. While it's generally recommended to use stainless steel electrodes for dissimilar material welding, the specific choice depends on detailed analysis and past experience. After evaluating the performance and characteristics of the electrode, we concluded that A307 was the best fit. The tensile strength of A307 is around 550MPa, making it suitable for both 40Cr and 20 steel.
3. Specific Implementation and Results
We decided to use φ4mm A307 stainless steel electrodes, which were baked for 1 hour at 250°C before welding. Unlike the previous method, there was no need for preheating. We simply cleaned the weld area with acetone, and no post-weld heat treatment was required. The welding current was set to 140A with DC reverse polarity.
The cylinders welded using A307 electrodes performed exceptionally well. They passed all quality checks smoothly, significantly improved production efficiency, and opened up a new and effective method for welding dissimilar materials within our company. This change not only saved time and resources but also enhanced the overall quality of the final product.
