Because of its natural oxide protective layer, stainless steel is an excellent choice for durability and product lifespan. If appropriate practices are not followed, warping, corrosion, and even metallurgical changes can occur.
Metalworkers unfamiliar with stainless steel fabrication, Sydney, as well as experienced welders and fabricators in a hurry, must pay special attention to proper Martain Stainless Steel working techniques and processes in order to preserve the metal’s integrity and keep the final product in spec.
Learn why adding surface contamination is one of the most dangerous mistakes to make when working with stainless steel and how to avoid this and other faults during the fabrication process.
Changes in Metallurgy
How it occurs:
- Because stainless steel has a lower thermal diffusivity (4.2 mm2/s) than other metals, the Heat Affected Zone (HAZ) during welding or thermal cutting is bigger.
- This can result in a grade change (austenitic stainless steel becoming martensitic, more brittle, and harder) or weakening of the heated metal.
Options for cutting:
Experts discuss the four methods of cutting and the aspects to consider when using them during stainless steel manufacturing in the post of HAZ.
Waterjet cutting, shearing, and manual cutting
They do not generate a HAZ since the sheet metal is not overheated.
Laser cutting
Because it applies heat to a relatively small region, it produces the least HAZ of any thermal cutting technique.
Cutting using plasma
Because the plasma pulse is wider than a laser beam, it produces an intermediate HAZ. Higher currents allow for a faster cutting speed, which reduces the exposure time and HAZ width.
Cutting with oxyacetylene
Because of the tremendous heat, moderate pace, and wide flames, it produces the widest HAZ of any thermal cutting technique.
Weld Deterioration:
Welding can cause chromium depletion in the base metal near the weld due to intense localized heat. The metal becomes more corrosive as a result of this alteration. These options for controlling stainless steel sensitization were listed in a study.
- A high-temperature anneal and quench after welding to redissolve chromium at grain boundaries and prevent chromium carbide production.
- To avoid carbide formation, choose a low-carbon stainless steel grade (e.g., 304L or 316L).
- A chrome-rich alloy (e.g., alloy 310)
Distortion
How it occurs:
Because of its low heat conductivity and fast expansion rate, stainless steel is prone to distortion during welding.
Welding Advice:
- Use the lowest feasible amperage without affecting weld quality.
- Interpass temperatures are controlled.
- Use a copper backing plate, clamping jigs, or controlled tack welding.
Surface Contaminants are Introduced
How it occurs:
- Stainless steel comes into contact with iron filings and other environmental pollutants.
- Hand grease, chalk, and other objects brought into contact with the surface while handling can contaminate it.
- Both of these factors can contribute to localized rust.
Contamination of the Surface:
- Use stainless steel abrasive for grinding, blending, and deburring.
- Separate stainless steel abrasive materials from abrasives used on different metals. Never use an abrasive that has previously been used on a different metal.
- Stainless steel should be kept apart from carbon steel and other metals.
- Keep stainless steel in its container as long as possible to keep it safe from the weather.
- Remove any transport adhesives from the stainless steel since they can harden and cause crevice corrosion on the job site.
Conclusion:- You’ll get an in-spec, well-finished stainless steel product if you use proper welding and cutting processes, are aware of the HAZ, and follow appropriate quality control and anti-contamination measures. To avoid typical stainless steel manufacturing blunders, make sure you and your team read this article.
