Project Description

AISI 9840 steel Manufacturer and Exporter,supplied with round,square,flat,block,and shaft etc.

AISI 9840 is defined as Cr-Ni-Mo series alloy steel as per USA standard ASTM A519.AISI 9840 steel is very similar to AISI 4340 steel, only the Ni element is lower, and the difference in other elements is almost negligible.

AISI 9840 steel has excellent performance after heat treatment, such as hardenability, strength and toughness, and wear resistance.It is usually used for seamless mechanical tubing,and also suitable for engineering applications,such as shafts,connected rods,gear shafts and crankshafts.

AISI 9840 Forged Flat steel with QT condition

AISI 9840 STEEL SUPPLY FORM & SIZE & TOLERANCE

Hot Forged Round bar:Φ80-Φ1000mm

Hot Rolled  Round bar:Φ16-Φ130mm

Hot Forged Square bar: Max Thickness:500mm

Flat bar/Blcoks:Thickness :120-800mm ,Width:120-1500mm

Surface FinishBlack-Forged Black-Rolled Turned   GrindingPolishedPeeledCold Drawn
Tolerance(0,+5mm)(0,+1mm)(0,+3mm)Best h9Best h11Best H11Best H11

AISI 9840 STEEL CHEMICAL COMPOSITION

GradeCSiMnPSCrMoNi
98400.38-0.420.15-0.350.7-0.9≤0.04≤0.040.7-0.90.20-0.300.85-1.15

AISI 9840 STEEL RELATED STANDARD & EQUIVALENT GRADE

China/GB 3077: 40CrNiMoA

Europe/EN10083: 39NiCrMo3/1.6510

Germany/DIN 17200: 36CrNiMo4/1.6511

WHAT IS AISI 9840 STEEL?

AISI 9840 steel is called Triple Alloy Steel because it has three main alloying elements: Cr-Ni-Mo.According to the SAE/AISI steel numbering designation system,we can clearly understand the meaning of 98XX from the table below.

TypeAISI/SAE DesignationChemical Composition


Nickel-Chromium-Molybdenum Steel
93XXNi 3.25%, Cr 1.20%, Mo 0.12%
94XXNi 0.45%, Cr 0.40%, Mo 0.12%
97XXNi 0.55%, Cr 0.20%, Mo 0.20%
98XXNi 1.00%, Cr 0.80%, Mo 0.25%

And the meaning of the last two “40” in the steel number 9840, it is very simple and clear to tell us that its average carbon content is 0.40% (0.38%-0.42%).

AISI 9840 STEEL FORGING

  • Initial Forging Temperature:1150℃
  • Final Forging Temperature:850℃
  • Forging Ratio:above 4:1

Post-Forging Treatment:AISI 9840 steel,as white-spot sensitive steel, is prone to cracks due to improper cooling after forged,so the recommended method is to arrange annealing heat treatment immediately after forging.

Advantages: First, it can eliminate processing stress and soften the material for further processing.Secondly, it can be used as a dehydrogenation heat treatment to prevent white spot defects and avoid material scrap.

AISI 9840 STEEL HEAT TREATMENT

  • AISI 9840 Steel Annealing & Normalizing

Annealing and normalizing of AISI 9840 steel are used as conventional preparatory heat treatment and are often used in actual production. Let’s take a look at their main characteristics.

AISI 9840 AnnealingAISI 9840 Normalizing
Temperature,℃840-880890-920
CoolingFurnace CoolingAir Cooling
Cooling Speed RateMuch SlowlyQuickly
Grain sizeNormalFine
Machinability Good Normal
Heat Treatment CycleLong timeShort time
Surface Hardness,HBW≤269/

AISI 9840 Forged steel for Normalizing

AISI 9840 Forged Round Steel For Normalizing

AISI 9840 Steel Mechanical Properties

Tensile Strength Yield StrengthElongationReduction of Area Impact Charpy-V Hardness
Normalizing1280Mpa860Mpa12.2%36%16363HBW
Annealing745Mpa470Mpa22%50%51217HBW
  • AISI 9840 Steel Quenching & Tempering(Q&T)

For Cr-Ni-Mo triple low alloy steel,there is no doubt that the maximum performance of the material itself needs to be achieved through quenching and tempering heat treatment,so is AISI 9840 steel.

For AISI 9840 steel, the recommended quenching temperature is between 840-860ºC with quench medium oil,and the holding time depends on the thickness of the material.It can achieve hardness 55-59HRC after quenched.

AISI 9840 steel Quenching Diagram

AISI 9840 Steel Quenching Diagram

Tempering process for AISI 9840 steel should be followed after quenching immediately.The recommended tempering temperature is generally between 550-650°C with hardness range 27-34HRC.

AISI 9840 Steel Tempering Diagram

AISI 9840 Steel Tempering Diagram

AISI 9840 Steel Tempering Temperature Vs Hardness


Grade
QuenchingTempering Temperature,ºC
Temperature,ºC Hardness150ºC 200ºC 300ºC 400ºC 500ºC 550ºC 600ºC 650ºC
9840850ºC >555554494438343027

AISI 9840 Steel Mechanical Property with Quenched and Tempered Condition

Quenching TemperatureQuenching MediumTempering TemperatureTensile Strength
Mpa
Yield Strength
Mpa
Elongation
%
Reduction
%
Charpy Impact
J

850ºC

Oil
400ºC≥1900≥1700≥5≥20≥30
600ºC≥1000≥850≥12≥55≥100
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