Stainless Steel-409L

AISI-409L is a stabilized version of AISI-409 that contains chromium as well as some nitrogen and carbon. This stainless steel grade is widely used by manufacturers for a variety of applications and equipment. AISI-409L is a low-cost corrosion-resistant stainless steel option. It also has a good combination of corrosion and heat resistance, making it an excellent choice for mildly corrosive applications or environments.

Classification

Ferritic stainless steel

Application

It is widely used in automotive exhaust systems, heat exchangers, catalytic converter systems, culverts, home heating systems, automotive thermostats, fuel filters, farm equipment components, electrical transformer cases.

Processing

Heat to 790-900°C and air cool. This grade cannot be hardened by thermal treatment.

Forming

Cold forming with a small degree of deformation is simple at temperatures above room temperature. Avoid sharp bending parallel to the rolling direction. Plates with greater thicknesses and/or degrees of deformation should be preheated to temperatures ranging from 200 to 400°C. If necessary, hot forming at 700 to 900°C may be required. Hot forming or annealing colors after welding or scaling reduce corrosion resistance. Pickling (pickling solution), grinding, or sand blasting are required to remove these. Only iron-free tools are permitted for these operations. Machining is identical to that of unalloyed carbon steels with comparable respective corresponding strength.

Weldability

Welding is simple, but a pre-heat of 150-260°C is advised. Although AISI-409 or AISI-430 electrode or filler rods can be used, AS 1554.6 requires AISI-409L rods or electrodes to be used. These austenitic fillers make the weld more ductile. Weld ductility is improved by post-weld annealing at 760-815°C. Post-weld annealing is not required when welding thin sections. Typically, automotive exhaust tubing is welded without the use of filler metal (autogenously). To reduce the effects of grain growth, all welding must be performed with the least amount of heat input.

Corrosion

Welding is simple, but a pre-heat of 150-260°C is advised. Although AISI-409 or AISI-430 electrode or filler rods can be used, AS 1554.6 requires AISI-409L rods or electrodes to be used. These austenitic fillers make the weld more ductile. Weld ductility is improved by post-weld annealing at 760-815°C. Post-weld annealing is not required when welding thin sections. Typically, automotive exhaust tubing is welded without the use of filler metal (autogenously). To reduce the effects of grain growth, all welding must be performed with the least amount of heat input.