Welding Digest

While not as common as its workhorse cousin, carbon steel, stainless steel offers corrosion-resistant benefits that make it a popular choice for many applications across numerous industries, including construction, shipbuilding, storage, and food and beverage processing.   

Stainless steel has a protective coating — a chromium oxide layer across the surface — that grants it good resistance to corrosion, rust, and oxidation. However, this characteristic presents some challenges when properly storing, handling, and working with stainless steel.   

Learning to avoid common mistakes when cutting and grinding stainless steel using bonded abrasive products helps ensure successful results when working with the material. 

What Makes Stainless Steel Different? 

Stainless steel and carbon steel have the same basic composition of iron and carbon, but stainless steel has a higher chromium content as its alloying element, which helps provide the protective layer. When working with stainless steel, one of the most critical challenges is avoiding contamination or damage to that oxide layer. 

In addition, stainless steel is a high-value material compared to basic carbon steel. It costs more to produce and purchase, so any mistakes that cause rework or scrap of parts and material can be especially costly for an operation. Not only are the damaged or scrapped parts costly, but so is the added labor time for any rework. Companies often have their most skilled operators working on high-value parts, like those made from stainless steel, which can increase the labor costs of rework.  

Often, an operator can feel like they’re doing less work when cutting or grinding stainless steel vs. carbon steel. This may cause them to change their cutting or grinding style or apply more pressure, which is a big no-no. Here are some tips for maximizing efficiency and eliminating contamination when cutting and grinding stainless steel.  

Tip 1: Choose Products Designed for Stainless Steel 

A key factor is ensuring that the correct product is being used. When using bonded abrasives like grinding and cutting wheels on stainless steel, look for products designed to avoid contamination. These contaminant-free products, typically labeled INOX, contain little to no iron, sulfur, and chlorine, resulting in a worry-free solution for stainless steel applications. Many general-purpose abrasive products contain iron, and using these products on stainless steel can leave residue that results in after-rust.  

While contaminant-free products labeled as INOX can also be used to cut or grind carbon steel, a wheel that has been used on steel should never be used on stainless steel because it can cause cross-contamination.  

Choosing the appropriate cutting and grinding products for stainless steel is a key first step. 

Tip 2: Use Proper Storage and Handling 

Companies that work with stainless steel face several challenges to eliminating the chance of cross-contamination. The following are some typical occurrences that can happen to even the most experienced workers. 

Cross-contamination commonly occurs when the wrong abrasive product is used on stainless steel or when a stainless steel wheel that has already been used on carbon steel is used on stainless. However, contamination can also happen through improper storage and handling practices.  

Storage and handling are more important than you think. For example, don’t store stainless steel and carbon steel in the same bin or place stainless steel material on a carbon steel shelf, as this can cause it to pick up contaminants. To avoid this, many companies place a piece of wood or some noncontaminating barrier between a carbon steel shelf and stainless steel parts or materials. 

Some large end-users build physical barriers between steel and stainless/aluminum production and keep operations in separate bays or cells as an added step to prevent cross-contamination. 

Because cross-contamination can occur in multiple ways, it’s important to take steps to safeguard against all possible contamination sources.  

Tip 3: Be Careful with Heat 

Stainless steel is typically more labor intensive to grind, especially when using the wrong abrasive. Operators may grind with more force or dwell too long in spots. As a result, more heat is produced, which is the nemesis when working with stainless steel. Too much heat or dwelling in the same area too long can cause discoloration on the material surface, leading to rework or even product scrap.  

Again, choosing high-performance products designed for stainless steel will help reduce the labor involved with grinding the material. Abrasives that are contaminant-free and use ceramic grains are a great choice. They self-sharpen and maintain a consistent cut rate throughout their life, which allows the operator to achieve the desired results without heavy pressure. In addition, using proper technique can help reduce heat buildup. Be sure to use constant, fluid movements and longer strokes when working with stainless steel and avoid dwelling in one spot. It’s also important to avoid using too much pressure with stainless steel. When operators have to press hard to get the performance they want from a product, they are likely using the wrong product.  

Products Available for Stainless Steel  

All the same basic styles of abrasive products used for cutting and grinding carbon steel are also available for stainless steel. As previously mentioned, products specifically designed for INOX and/or that contain ceramic grains are the best options for most stainless applications. 

The self-sharpening crystals of ceramic grains in those products allow operators to use lighter or medium pressure, which helps prevent heat discoloration and allows them to cut through the material more easily.  

Aluminum oxide is also a good general-purpose grain that is available in contaminant-free wheel options. In addition, new technologies are helping to drive advancements in cutting and grinding stainless steel. 

Optimizing Results with Stainless Steel  

When working with stainless steel, never cut corners when selecting or storing abrasives. Because stainless steel offers specific characteristics, it is often used on high-value parts, and mistakes can be costly. Following these tips for abrasive product selection, operator technique, and handling and storage of stainless steel can help operations get better results when cutting and grinding the material. 

This article was written by Tony Hufford (category manager of metal fabrication at Weiler Abrasives) for the American Welding Society.