Sanmac 4435 (Billets)

Chemical composition (nominal) %

Forms of supply

Sizes and tolerances

Round-cornered square, as well as round billets, are produced in a wide range of sizes according to the following tables. Larger sizes offered on request.

Surface conditions

Square billets

Unground, spot ground or fully ground condition.

Round billets

Peel turned or black condition.

Sizes and tolerances apply to the rolled/forged condition.

Other products

• Solid bar (Sanmac)
• Hollow bar (Sanmac)
• Welding wire
• Covered electrodes

Mechanical properties

Testing is performed on separately solution annealed and quenched test pieces. The following figures apply to material in the solution annealed and quenched condition.

At 20°C (68°F)

1 MPa = 1 N/mm²
a) R_p0.2 and R_p1.0 correspond to 0.2% offset and 1.0% offset yield strengths, respectively.
b) Based on L₀ = 5.65 √S₀ where L₀ is the original gauge length and S₀ the original cross-sectional area.

The impact energy (Charpy V) at 20°C (68°F) is min 100 J (74 ft-lb).

At high temperatures

Imperial units

Physical properties

Density: 8.0 g/cm³ , 0.29 lb/in³

1) Mean values in temperature ranges (x10^-6)

1) (x10³)

Corrosion resistance

General corrosion

Sanmac 4435 has good resistance in:

• Organic acids at high concentrations and moderate temperatures
• Inorganic acids, e.g. phosphoric and sulphuric acids, at moderate concentrations and temperatures. The steel can also be used in sulphuric acid with concentrations above 90% at low temperature.
• Salt solutions, e.g. sulphates, sulphides and sulphites
• Caustic environments.

Pitting and crevice corrosion

Resistance to these types of corrosion improves with an increasing molybdenum content. Sanmac 4435, containing about 2.6% molybdenum, has substantially higher resistance to attack than steels of type AISI 304 and also better resistance than ordinary AISI 316L steels with 2.1%.

Stress corrosion cracking

Austenitic steels are susceptible to stress corrosion cracking. This may occur at temperatures above about 60°C (140°F), if the steel is subjected to tensile stresses and at the same time comes into contact with certain solutions, particularly those containing chlorides. In applications demanding high resistance to stress corrosion cracking, we recommend the austenitic- ferritic steel Sanmac SAF 2205.

Gas corrosion

Sanmac 4435 can be used in:

• Air up to 850°C (1560°F)
• Steam up to 750°C (1380°F)

Creep behaviour should also be taken into account when using the steel in the creep range. In flue gases containing sulphur, corrosion resistance is reduced. In such environments, the steel can be used at temperatures up to 600–750°C (1110–1380°F), depending on service conditions. Factors to consider are whether the atmosphere is oxidizing or reducing, i.e. the oxygen content, and whether impurities such as sodium and vanadium, are present.

Hot working

Hot working should be carried out at a material temperature of 900-1200°C (1650-2190°F). Hot working of Sanmac 4435 should be followed by rapid cooling in air or in water. If additional heat treatment is needed, it should be carried out in accordance with the recommendations given for heat treatment.

Heat treatment

Sanmac 4435 billets are delivered in the hot worked condition. If another heat treatment is needed after further processing, the following is recommended.

Solution annealing

1040–1120°C (1900–2050°F), rapid cooling in air or water.

Welding

Suitable welding methods for Sanmac 4435 are manual metal-arc welding with covered electrodes and gas shielded arc welding, with the TIG and MIG methods as first choice. Preheating and post-weld heat treatment are not normally necessary. Due to the fact that this material is alloyed in such a way that it has good machinability there can be a higher amount of surface oxides on the weld beads, compared to standard 316L steels. This may lead to arc instability during TIG welding. Correct setting of the welding current is very important.

Since this material has low thermal conductivity and high thermal expansion, welding must be carried out with a low heat input and with welding plans well thought out in advance so that the deformation of the welded joint can be kept under control.

As filler metals for gas shielded arc welding we recommend wire electrodes and rods Sandvik 19.12.3.L,19.12.3.LSi. In manual metal-arc welding, covered electrodes Sandvik19.12.3.LR, 19.12.3.LB or 19.12.3.LRHD are recommended. Correct setting of the welding current is of the utmost importance.

Filler metals for welding

The sizes listed below are Sandvik stock standard. The local stocks carry sizes in common demand on the market. For technical information on filler metals, please refer to brochure S-236-ENG.

Wire electrodes and filler wire/rods

Sandvik 19.12.3.L
Sandvik 19.12.3.LSi

Covered electrodes

Sandvik 19.12.3.LR
Sandvik 19.12.3.LB
Sandvik 19.12.3.LRHD

Machining

General

Sanmac stands for Sandvik Machinability Concept. In Sanmac materials, machinability has been improved without jeopardising properties such as corrosion resistance and mechanical strength.

Improved machinability is brouhgt about by:

• Optimised non-metallic inclusions
• Optimum chemical composition
• Optimised process and production parameters

Detailed recommendations for the choice of tools and cutting data, for turning, thread cutting, parting/grooving, drilling, milling and sawing, are provided in the brochure S-029-ENG.

Machining chart

The diagram shows the ranges, within which data should be chosen in order to obtain a tool life of 10 minutes minimum, when machining the austenitic Sanmac 4435. The ranges are limited in the event of low feeds because of unacceptable chip breaking. In the case of high cutting speeds, plastic deformation is the most dominant cause of failure. When feed increases and the cutting speed falls, edge frittering (chipping) increases significantly. The diagram is applicable for short cutting times. For long, continuous cuts, cutting speeds should be reduced.

Figure 1. Machining chart for Sanmac 4435.

The lowest recommended cutting speed is determined by the tendency of the material to stick to the insert (built-up edge), although the integrity of insert clamping and the stability of the machine are also of great significance.

It is important to conclude, which wear mechanism is active, in order to optimise cutting data with the aid of the diagram.

Turning Sanmac 4435

Recommended insert and cutting data (starting values)

Drilling Sanmac 4435

The recommended methods for drilling give the most cost effective results for the respective diameter ranges. When producing holes with diameters larger than 58 mm, short hole drilling is used up to 58 mm, followed by internal turning, up to the desired diameter. Cutting data for internal turning should be chosen in accordance with the turning recommendations. The recommendations for drilling are applicable for a tool life of 30 minutes.

Short hole drilling, diameter 12.7 - 58 mm

Coromant U-drill, R416.2

* GC1120 for diameters below 17.5 mm
** stable conditions, otherwise use GC1020

Drilling with Sandvik Coromant Delta C drill, diameter 3 - 12.7 mm

Code R415.5. Grade GC1220
(diameter range 3 - 20 mm)

* The lower feed value should be selected for smaller diameters

Drilling with high speed steel (HSS) drill

(diameter 1-3 mm)

* The lower feed value should be selected for smaller diameters
** The higher cutting speed should be selected for coated drills

Milling Sanmac 4435

Use of optimum cutting data means that milling can be carried out at cutting speeds above those where there is a risk of built-up edge formation. Dry milling results in long tool life. If coolant is needed (e.g. when the surface cannot be reached in the dry condition), the cutting speed must be reduced by approximately 40-60% to prevent tool wear due to increased thermal load on the inserts.

Threading Sanmac 4435

Indexable inserts can be used for external thread cutting of all diameters. Threading with screw-cutting dies or die heads is economical only for small diameters. For internal threading with short and normal cutting lengths, thread cutting with indexable inserts is recommended above a hole diameter of 12 mm. For long cutting lengths, thread cutting with indexable inserts is recommended for hole diameters above 20 mm.

Thread turning

Due to the tendency of austenitic materials to work harden, radial infeed is recommended. A generous flow of cutting fluid should also be used, partly to obtain a reliable process and partly to guide the chip. The recommendations apply to a tool life of 30 minutes.

Thread tapping

Compared with uncoated threading taps, coated threading taps can improve productivity by up to 100%. For the advantages of coated threading taps to be realised, a generous flow of cooling fluid must be used. The recommendations apply to a tool life of 30 minutes.

The higher range of cutting data should be chosen for coated threading taps

Sawing of Sanmac 4435

Cutting with bandsaws or cold saws gives the best cutting economy. If the demand for surface smoothness is great, circular sawing is preferable. Band sawing gives high productivity, is flexible and incurs low investment costs.

When band sawing Sanmac 4435, the Sandflex Cobra type 3851 bimetallic bandsaw blades, which is available from Bahco Group (formerly Sandvik Saws and Tools), is recommended.

Tooth spacing should be selected according to the dimensions of the material to be cut, and stated in TPI (the number of teeth per in.). The TPI should be reduced for thicker dimensions. For a bar dimension of D = 150 mm, 2/3 TPI or 1/2 TPI is recommended.

Feed is regulated to obtain a good chip form.

Applications

Sanmac 4435 is used for a wide range of industrial applications, where steels of type AISI 304/304L have insufficient corrosion resistance.