| Chemical Composition |
| Min. % | Max % |
| Carbon | 0.09 | 0.15 |
| Silicon | 0 | 1.00 |
| Manganese | 0 | 1.50 |
| *Nickel | 0 | 1.00 |
| Chromium | 11.50 | 14.00 |
| *Molybdenum | 0 | 0.60 |
| Phosphorous | 0 | 0.0.6 |
| Sulphur | 0.15 | 0.35 |
| *Nickel & Molybdenum additional option |
| Mechanical Property Requirements For Material in the Annealed and
Heat Treated - Condition P To AS2837 - 1986 416 and BS970 Part3
1991 416S21 |
| Condition | Annealed | P |
| Tensile Strength Mpa | Min | | 550 |
| Max | | 700 |
| 0.2% Yield Strength Mpa | Min | | 340 |
| Elongation on 5.65√S0 % | Min | | 15 |
| Impact Izod J | Min | | 34 |
| Hardness HB | Min | | 152 |
| Max | 207 | 207 |
| Material stocked generally in annealed condition 76.2 mm dia and
larger.Material stocked generally in condition P up to and
including 63.5 mm dia. NB. Check the mill certificate if critical
for end use. |
| Typical Mechanical Properties At Room Temperature - Annealed and
Hardened and Tempered to Condition P |
| Condition | Annealed | *P |
| Tensile Strength Mpa | 530 | 650 |
| 0.2% Yield Strength Mpa | 290 | 490 |
| Elongation in 50mm % | 27 | 24 |
| Impact Izod J | 75 | 95 |
| Hardness HB | 160 | 190 |
| *Typical Hardening Temperatures | 950oC - 1010oC |
| *Typical Tempering Temperatures | 650oC - 680oC |
| 620oC - 660oC |
| Typical Mechanical Properties At Room Temperature - Hardened By Oil
Quench at 980oC and Tempered as Indicated |
| Temperature oC | 150 | 250 | 370 | 480 | 540 | 595 | 650 | 700 |
| Tensile Strengt Mpa | 1210 | 1190 | 1180 | 1100 | 950 | 780 | 710 | 660 |
| 0.2% Yield Strength Mpa | 950 | 940 | 930 | 870 | 760 | 650 | 570 | 520 |
| Elongation in 50mm % | 10 | 11 | 14 | 15 | 16 | 17 | 21 | 22 |
| Impact | Izod J | 27 | 34 | 34 | *22 | *34 | 54 | 65 | 105 |
| Charpy J | 27 | 30 | 30 | *20 | *30 | 54 | 68 | 100 |
| Hardness | HB | 360 | 350 | 350 | 330 | 285 | 235 | 205 | 190 |
| Rc | 39 | 38 | 38 | 36 | 31 | 23 | 16 | 12 |
| High tensile strength and high yield strength but low impact
properties when tempered below 400oC.*Note drop in impact
properties.Tempering within the range 400oC - 580oC should be
avoided. |
| Elevated Temperature Properties |
| While 416 displays a reasonable resistance to scaling in continuous
service up to 650oC, it does however experience a substantial drop
in tensile strength, creep and stress rupture strength at
relatively low working temperatures. It is also susceptible to hot
cracking due to its high sulphur content.NB. High temperature use
is therefore not generally recommended. |
| Low Temperature Properties |
| 416 is not recommended for use at sub-zero temperatures due to a
substantial drop in impact properties consistent with most steels
other than the austenitic steel types. |
| Cold Bending |
| 416 has limited cold bending properties and it is generally not
recommended. |
| Hot Bending |
| In the hardened and tempered condition, it is not recommended due
to its affect on the mechanical properties within the heat affected
zone. Even in the annealed condition it should also be avoided if
possible due to its susceptibility to hot cracking. |
| Corrosion Resistance |
416 due to its higher sulphur content has lower resistance to all
corrosion types than grade 410, and indeed all of the 400 series
martensitic stainless steels.Its selection therefore is generally
based upon its excellent machinability coupled with its lower
corrosion resistance capabilities. NB. It has optimum corrosion
resistance in the hardened and tempered condition and is not
therefore recommended for use in the annealed condition.It is most
important that oxygen is always allowed to circulate freely on all
stainless steel surfaces to ensure that a chrome oxide film is
always present to protect it. If this is not the case, rusting will
occur as with other types of non stainless steels.
For optimum corrosion resistance surfaces must be free of scale and
foreign particles.
Finished parts should be passivated.
|
| Forging |
Heat uniformly to 1150oC - 1200oC, hold until temperature is
uniform throughout the section.Do not soak but commence forging
immediately. Do not overheat as this can cause a loss of toughness
and ductility.Do not forge below 900oC
Finished forgings should be cooled slowly in air, ashes or dry lime
etc. to room temperature and annealed immediately. NB. Severe upset forging of this grade is not recommended.
|
| Heat Treatment |
| Sub-Critical Annealing |
| Heat uniformerly to 650oC - 750oC as required, hold until
temperature is uniform throughout the section.*Soak as required,
cool in air. |
| Annealing |
| Heat to 820oC - 900oC, hold until temperature is uniform throughout
the section. *Soak as required. Cool in furnace. |
| Hardening |
| Heat to 950oC - 1020oC, hold until temperature is uniform
throughout the section. *Soak as required.Quench in oil or air
cool. Temper immediately while still hand warm. |
| Nitriding |
| Prior to nitriding, the chrome oxide film which protects the
surface must be broken down by pickling or fine sand
blasting.Nitriding is carried out at 500oC - 550oC followed by slow
cooling (no quench) reducing the problem of distortion. Parts can
therefore be machined to near final size, leaving a grinding
tolerance only. Always ensure that the tempering temperature
employed during the initial heat treatment was higher than the
nitriding temperature otherwise the core strength will be affected. |
| Tempering (Condition R) |
Heat to 650oC - 750oC as required, hold until temperature is
uniform throughout the section. *Soak as required. Cool in air.416
can of course be tempered at much lower temperatures, producing
much higher tensile strengths, but with subsequent lower impact
properties. NB. Tempering however within the range 400oC - 580oC
should be avoided due to the brittleness, resulting in a
considerable reduction in impact properties and loss of corrosion
resistance.*Heating temperatures, rate of heating, cooling and
soaking times will vary due to factors such as work piece
size/shape, also furnace type employed, quenching medium and work
piece transfer facilities etc.
Please consult your heat treater for best results.
|
| Machining |
| 416 was developed as a free machining grade and has by far the best
machinability of all the 400 series martensitic stainless steels.
It also has much better machinability than grade 303 free machining
austenitic stainless steel and all operations such as turning,
drilling, broaching, tapping, milling, reaming and threading etc.
can be readily carried out as per machine manufacturers
recommendations for suitable tool type, feeds and speeds. |
| Welding |
| 416 is not generally recommended for welding in either the annealed
or hardened and tempered condition, due to its high sulphur content
resulting in hot cracking or its hardening capability resulting in
cold cracking.If it is really necessary to weld in either condition
the following procedure may be taken as a guide only. |
| Welding Procedure |
Welding electrodes or rods should be low hydrogen types 410 or
*similar when strength is required or post-weld hardening and
tempering, otherwise an austenitic stainless electrode or rod such
as 308 or *similar may be used to give a more ductile weld, when
strength is not so critical and post-weld annealing is not possible
or intended.Pre-heat at 200oC - 300oC and keep heat input to a
minimum to reduce dilution of sulphur and filler metal. On
completion of welding cool slowly as possible until hand warm and
as required: Post-weld sub-critical anneal at 650oC - 750oC or full
anneal and harden and temper as required.*Please consult your
welding consumables supplier.
|
