Stainless steel is a very durable, but also versatile metal and because of that, there are many stainless steel fabricating techniques you can use. It’s recommended that you review the techniques prior to using them, since this way you’ll gain a much better understanding of the pros and cons of the various types of stainless steel fabrication processes. While stainless steel does have relatively high work hardening and strength rates, it is malleable enough to the point where it can be spun, deep drawn, welded, but also machined, folded and bent by using the right tools. With that in mind, below we’ll discuss more about the various stainless steel fabricating processes.
Work hardening with stainless steel is basically a process that deforms the metal in order to strengthen it. In general, stainless steel can harden quickly, but this does actually depend on the grade of the alloy used. For instance, compared to carbon steel, the austenitic family of stainless steel has a slight higher hardening rate and that is why it’s frequently use in various fabrication processes. It’s very important that the steel grade be matched with a specific work hardening treatment that’s proper for it. When it comes to austenitic stainless steel, cold working seems to be one of the best ways to harden it, with thermal treatment processes only being recommended for other grades.
Stainless Steel Work Hardening Rates
Lower work hardening rates are generally associated with ferritic SS and because of that, it seems that martensitic and austenitic SS are the only 2 series that benefit the most from work hardening applications. There are even cases where austenitic SS can be cold worked up to one thousand MPa, but the maximum is somewhere around eight hundred MPa. If it’s cold drawn, then the SS can achieve tensile properties of up to two thousand MPa and sometimes even greater than that. Such tensile properties though seem to generally be limited to fine wire sizes.
Other Characteristics of Stainless Steel
Stainless steel has a very slight magnetism, but the truth is that it can be significantly improved through work hardening. This means that if a piece of SS is subjected to a work hardening process, then it will exhibit higher magnetic rates post treatment. SS will also deform more at low forming speeds, so in order for the work hardening process to be as efficient as possible, the high speed forming process needs to be slowed down.
Machining Stainless Steel
Grades three hundred and three, four hundred and thirty, four hundred and ten and four hundred and sixteen develop chipping resistance when alloyed with manganese sulfide. When manganese sulfide is added, stainless steel becomes less resistant to corrosion and ductility and therefore has limited machining applications. In order to combat this, it seems that several companies have developed steel melting techniques that make it easier for them to machine this type of steel. As a result, the process will not only improve machining efficiency, but also increase the lifespan of the tools made using this type of steel.
Machine Stainless Steel
Machining stainless steel can be a very complex process at times and that’s especially the case when certain risks are taken into consideration. If you plan on machining this type of alloy, be sure to check out these tips:
1. Ensure the cutting edge is kept sharp at all times.
2. Go for a machine tool that minimizes vibration.
3. Deflect debris by using chip breakers.
4. Maintain constant feeds and light cuts.
5. Dissipate heat by using larger tools.
6. Ensure the equipment is properly lubricated and apply coolants on it.
Welding Stainless Steel
The majority of stainless steel types can be welded, yet when it comes to efficiency, it seems to depend on the grade. Below we’ll take a closer look at how you can weld certain types of stainless steel categories.
Duplex: For low thermal expansion, this set of grades is definitively a great choice. Welding grades such as Grade two thousand two hundred and five have a higher nickel content which is great for improving corrosion resistance, strength and ductility.
Ferritic stainless steel: As with other types of stainless steel, you may run into issues such as low ductility, sensitization and high grain growth. To overcome them, use austenitic stainless steel fillers.
Martensitic: While these grades can be welded, there is a chance they’ll crack in the process. To make sure that won’t happen, the material needs to be heated before and post welding.
Austenitic: The majority of grades of the austenitic family can be easily sued for welding, with the exception of free machining Grade three hundred and three. It’s important to bear in mind though that this group is indeed susceptible to inter granular corrosion and sensitization on thicker products.