416 Stainless Steel 416 Stainless Steel Tubing

Type 416 Stainless Steel is a stainless steel which is martensitic and can be hardened by heat treatment to higher strength and hardness levels. It has much better machining properties than the austenitic grades, but lower corrosion resistance. In dry conditions and in environments that are mildly corrosive, 416 machining grade is practically comparable with unmodified types. Type 416 is somewhat inferior in corrosion resistance to other 12% chromium stainless steels, such as type 410. Type 416 Stainless Steel may also be heat treated to varying degrees of strength and hardness by appropriate treatment. It may be used in welding, with some difficulty, and it must be annealed after welding at about 1450° F to improve its ductility and corrosion resistance.

416 Stainless Steel is a martensitic free machining grade of stainless steel that can be hardened by heat treatment to achieve elevated strength and hardness. Due to its low cost and ready machinability, 416 stainless steel is readily used in its highly tempered state. It exhibits better machining characteristics than austenitic grades, however, sacrifices corrosion resistance. Since 416 stainless steel is free of high sulfer content it is not suitable for marine or any chloride exposure situations. We can supply our 416 stainless steel for any project big or small.

Grade 416 is sometimes used in the unhardened or hardened and highly tempered condition because of its low cost and ready machinability.

Grade 416 has the highest machinability of any stainless steel, at about 85% of that of a free-machining carbon steel. As for most other free-machining stainless steel the improvement in machinability is achieved by addition of sulphur which forms manganese sulphide inclusions; this sulphur addition also lowers the corrosion resistance, weldability and formability to below that of its non-free machining equivalent Grade 410.

Martensitic stainless steel are optimised for high hardness, and other properties are to some degree compromised. Fabrication must be by methods that allow for poor weldability and usually also allow for a final harden and temper heat treatment. Corrosion resistance is lower than the common austenitic grades, and their useful operating temperature range is limited by their loss of ductility at sub-zero temperatures and loss of strength by over-tempering at elevated temperatures.

These properties are specified for bar product in ASTM A582. Similar but not necessarily identical properties are specified for other products such as wire and forgings in their respective specificationsChemical Composition

Typical compositional ranges for grade 416 stainless steel are given in table 1.

Table 1.Composition ranges for 416 grade stainless steel

Mechanical Properties

Typical mechanical properties for grade 416 stainless steel are given in table 2.

Table 2.Mechanical properties of 416 grade stainless steel

* Annealed properties are typical for Condition A of ASTM A582.
** Hardened and tempered Condition T of ASTM A582 – Brinell Hardness is specified range, other properties are typical only.
# Due to associated low impact resistance this steel should not be tempered in the range 400-580°C

Physical Properties

Typical physical properties for annealed grade 416 stainless steels are given in table 3.

Table 3. Physical properties of 416 grade stainless steel in the annealed condition

416 Stainless Steel Grade Specification Comparison

Approximate grade comparisons for 416 stainless steels are given in table 4.

Table 4. Grade specifications for 416 grade stainless steel

416 Stainless Steel Possible Alternative Grades

Possible alternative grades to grade 416 stainless steels are given in table 5.

Table 5. Possible alternative grades to 416 grade stainless steel

416 Stainless Steel Corrosion Resistance

Useful resistance to dry atmospheres, fresh water and mild alkalies and acids, but less resistant than the equivalent non-free-machining grades. Less corrosion resistant than the austenitic grades and also less than 17% chromium ferritic alloys such as Grade 430. High sulphur content free machining grades such as 416 are totally unsuitable for marine or other chloride exposure.

Maximum corrosion resistance is achieved in the hardened condition, with a smooth surface finish.

416 Stainless Steel Heat Resistance

Fair resistance to scaling in intermittent service up to 760°C and up to 675°C in continuous service. Not recommended for use in temperatures above the relevant tempering temperature, if maintenance of mechanical properties is important.

416 Stainless Steel Heat Treatment

Full Annealing – Heat to 815-900°C for ½ hour per 25mm of thickness. Cool at 30°C per hour maximum to 600°C and air cool.

Sub-Critical Annealing – Heat to 650-760°C and air cool.

Hardening – Hardened by heating to 925-1010°C, quenching in oil, and tempering to suit the mechanical requirements. See accompanying table.

Note: The tempering range 400-580°C should be avoided, due to poor ductility.

416 Stainless Steel Welding

Grade 416 has poor weldability. If welding is necessary use Grade 410 low hydrogen electrodes. Pre-heat to 200-300°C. Follow immediately with annealing or re-hardening, or a stress relief at 650-675°C.

A better option if the weld is not required to be hard is to use a Grade 309 austenitic stainless steel filler rod

416 Stainless Steel Machining

Grade 416 offers exceptionally good machinability, the highest of any of the commonly available stainless steels. Best machinability is in the sub-critical annealed condition.

416 Stainless Steel Applications

416 stainless is used for applications requiring good mechanical properties and involving corrosive conditions that are not too severe, such as valves and valve parts, machine parts, screws, bolts, pump rods, pistons, food industry machine parts, cutlery, etc. It can be turned, threaded, formed or drilled at speeds approaching those of screw stock. In the annealed condition, it can be drawn or formed. 416 is used for parts such as compressor shrouds, where oxidation resistance is required up to 1000° F. Useful at high temperatures only when stresses are low. Maximum corrosion resistance of 416 is obtained by hardening and polishing.

416 Stainless Steel Typical applications include:

•         Valve Parts

•         Pump Shafts

•         Automatic Screw Machined Parts

•         Motor Shafts

•         Washing Machine Components

•         Bolts and Nuts

•         Studs

•         Gears