AISI 4140 steel Manufacturer and Exporter, supplied with round, square, flat, block, and shaft etc. AISI 4140 is defined as a low alloy steel which has 1% Cr-Mo as strengthening alloy elements.Compared with AISI 4130, it has a higher carbon content with good balance of strength, toughness, abrasion and impact resistance and heat treatment capabilities, but poor in weldability characteristics. AISI 4140 is generally supplied in quenched and tempered condition with hardness 28-32HRC.
| Supply Form | Size(mm) | Process | Tolerance | |
| Round | Φ6-Φ100 | Cold Drawn | Bright/Black | Best H11 |
| Φ16-Φ350 | Hot Rolled | Black | -0/+1mm | |
| Peeled/ground | Best H11 | |||
| Φ90-Φ1000 | Hot Forged | Black | -0/+5mm | |
| Rough Turned | -0/+3mm | |||
| Flat/Square/Block | Thickness :120-800 | Hot Forged | Black | -0/+8mm |
| Width:120-1500 | Rough Machined | -0/+3mm | ||
Remark: Tolerance can be customized as per requests
| Standard | Grade | C | Si | Mn | P | S | Cr | Ni | Mo |
| ASTM A29 | 4140 | 0.38-0.43 | 0.15-0.35 | 0.75-1.00 | ≤ 0.035 | ≤ 0.04 | 0.8-1.1 | – | 0.15-0.25 |
| EN10083 | 42CrMo4 | 0.38-0.45 | ≤ 0.4 | 0.6-0.90 | ≤ 0.025 | ≤ 0.035 | 0.9-1.2 | – | 0.15-0.30 |
| 1.7225 | |||||||||
| JIS G4105 | SCM440 | 0.38-0.43 | 0.15-0.35 | 0.6-0.85 | ≤ 0.035 | ≤ 0.04 | 0.9-1.2 | – | 0.15-0.30 |
| GB 3077 | 42CrMo | 0.38-0.45 | 0.17-0.37 | 0.5-0.80 | ≤ 0.035 | ≤ 0.035 | 0.9-1.2 | – | 0.15-0.25 |
| BS 970 | EN19 | 0.35-0.45 | 0.15-0.35 | 0.5-0.80 | ≤ 0.035 | ≤ 0.035 | 0.9-1.5 | – | 0.2-0.40 |
| Density g/cm3 | 7.85 | ||||
| Melting point °C | 1416 | ||||
| Poisson's ratio | 0.27-0.30 | ||||
| Machinability (AISI 1212 as 100% machinability) | 65% | ||||
| Thermal expansion co-efficient µm/m°C | 12.2 | ||||
| Thermal conductivity W/(m.K) | 46 | ||||
| Modulus of elasticity 10^3 N/mm2 | 210 | ||||
| Electric resistivity Ohm.mm2 /m | 0.19 | ||||
| Specific heat capacity J/(kg.K) | 460 | ||||
| Modulus of elasticity 10^3 N/mm2 | 100 ℃ | 200 ℃ | 300 ℃ | 400 ℃ | 500 ℃ |
| 205 | 195 | 185 | 175 | 165 | |
| Thermal expansion 10^6 m/(m.K) | 100 ℃ | 200 ℃ | 300 ℃ | 400 ℃ | 500 ℃ |
| 11.1 | 12.1 | 12.9 | 13.5 | 13.9 | |
| Mechanical Condition | R | S | S | T | U | V | W |
| Ruling Section mm | 250 | 250 | 150 | 100 | 63 | 30 | 20 |
| Tensile Strength Mpa | 700-850 | 770-930 | 770-930 | 850-1000 | 930-1080 | 1000-1150 | 1080-1230 |
| Yield Strength Mpa Min | 480 | 540 | 570 | 655 | 740 | 835 | 925 |
| Elongation % | 15 | 13 | 15 | 13 | 12 | 12 | 12 |
| Izod Impact J Min | 34 | 27 | 54 | 54 | 47 | 47 | 40 |
| Charpy Impact J Min | 28 | 22 | 50 | 50 | 42 | 42 | 35 |
| Hardness Brinell HB | 201-255 | 233-277 | 233-277 | 248-302 | 269-331 | 293-352 | 311-375 |
| For quenched and tempered heavy forgings | |||||||
| Diameter mm | Yield strength MPa | ||||||
| 20 ℃ | 100 ℃ | 200 ℃ | 250 ℃ | 300 ℃ | 350℃ | 400℃ | |
| ≤250 | 510 | 486 | 461 | 441 | 422 | 392 | 363 |
| 250-500 | 460 | 431 | 412 | 402 | 382 | 353 | 324 |
| 500-750 | 390 | 333 | 333 | 324 | 304 | 275 | 245 |
Forging temperature should be carried out between 900℃-1200℃,The lower the forging-ending temperature ,the finer the grain size .Hold the temperature till uniform before forge,minimum forging temperature 850°C,so don’t forge below 850℃.AISI 4140 steel should be cooled as slowly as possible in still air or in sand after forged.
Normalizing is used to refine the structure of forgings that might have cooled non-uniformly after forged,and considered as a conditioning treatment before final heat treatment.Normalizing temperature for AISI 4140 steel should be carried out between 870℃-900℃. hold suitable time for the steel to be thoroughly heated to complete the ferrite to austenite transformation.Cool in still air.
After Forged,AISI 4140 steel may be annealed .Annealing temperature should be carried out between 800℃-850℃, hold suitable time for the steel to be thoroughly heated. Cool slowly in the furnace.This treatment will form a structure suitable for machining.The maximum Hardness is 241 HB.
This heat treatment will obtain martensite structure after quenched.It should be carried out between 840℃-875℃, hold suitable time for the steel to be thoroughly heated, soak for 10-15 minutes per 25 mm section, and quench in oil, water, or polymer as required.Tempering should be followed immediately after quenched.
Tempering is usually carried out to relieve stresses from the hardening process, but primarily to obtain the required hardness and mechanical properties. The actual tempering temperature will be chosen to meet the required properties.Heat the AISI 4140 carefully to a suitable temperature ,usually between 550℃-700℃, soak at the temperature for 2 hours per 25mm of ruling section, then cool in air.Tempering between 250℃-375℃ is not avoided as tempering within this range will seriously reduce the impact value,result in temper brittleness .
AISI 4140 steel finds many applications as forgings for the aerospace,oil and gas,automotive, agricultural and defense industries etc.
Typical applications for 4140 steel uses include:forged gears,spindles,fixtures,jigs,collars,Axles,conveyor parts,crow bars,logging parts,shafts,sprockets,studs,pinions,pump shafts, rams, and ring gears etc
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