42CrMo4 / DIN 1.7225 Steel

42CrMo4 is a heat treatable steel which contains at least 0.9%Cr,0.15%Mo as strengthening elements.After quenched and tempered, It obtains high strength, good low-temperature impact toughness with a typical tensile strength of 900 -1200 N/mm2.42CrMo4 steel has better performance than 34CrMo4 steel due to the higher carbon and chromium content.Similar to AISI 4140,only a little difference in Mn,Cr content.This material also has good machinability,good wear-resistance,but the temper brittleness is not obvious,and poor in weldability.

42CrMo4 Supply Form & Size & Tolerance

Form of Supply	Size(mm)	Length(mm)
Round bar	Φ6-Φ1,000	3,000-10,000
Square bar	100×100-600×600	3,000-6,000
Plate/Sheet	Thickness :20-400 Width:80-1,000	2,000-6,000
Flat bar/Blcoks	Thickness :120-800 Width:120-1,500	2,000-6,000

42CrMo4 Surface Finish&Tolerance

Surface Finish	Black-Forged	Black-Rolled	Turned	Grinding	Polished	Peeled	Cold Drawn
Tolerance	(0，+5mm)	(0，+1mm)	(0，+3mm)	Best h9	Best h11	Best H11	Best H11

42CrMo4 Chemical Composition per EN 10083-3

GRADE	NUMBER	C	Si	Mn	P	S	Cr	Mo
42CrMo4	1.7225	0.38-0.45	≤ 0.40	0.60-0.90	≤ 0.025	≤ 0.035	0.90-1.20	0.15-0.30

42CrMo4 Relevant Standards

USA	UK	China	Japan	France	Russia
4140	EN19/708M40	42CrMo	SCM440	42CD4	42HM

42CrMo4 Mechanical Property

Diameter d mm	≤ 16	16-40	40-100	100-160	160-250
Thickness t mm	< 8	8-20	20-60	60-100	100-160
Yield Strength Mpa	≥900	≥750	≥650	≥550	≥500
Tensile Strength Mpa	1100-1300	1000-1200	900-1100	800-950	750-900
Elongation, %	≥10	≥11	≥12	≥13	≥14
Reduction of area ,%	≥40	≥45	≥50	≥50	≥55
impact	≥30	≥35	≥35	≥35	≥35

42CrMo4 Forging

42CrMo4 forging temperature:900 – 1100°C ,cooling as slowly as possible in still air or in sand after forged.

42CrMo4 Heat Treatment

• Normalizing:  850 – 880°C,Cooling in air
• Soft Annealing:680 – 720°C,Cooling in furnace
• Stress relieve:450-650°C,Cooling in air
• Hardening:820 – 880°C,oil or water quench
• Tempering:540 – 680°C,Cooling in air

42CrMo4 Surface Hardness

• Treated to improve shearability (+S):Max 255HB
• Soft annealed (+A):Max 241HB
• Pre Quenched and tempered:280-320HB
• Flame or induction hardening:Min 53HRC

NORMAL HARDENABILITY +H (850°C – hardness HRC – distance mm)
Distance mm	1.5	3	5	7	9	11	13	15	20	25	30	35	40	45	50
HRC Min	53	53	52	51	49	43	40	37	34	32	31	30	30	29	29
HRC Max	61	61	61	60	60	59	59	58	56	53	51	48	47	46	45

Key Features and Benefits

1. High Strength and Toughness:
   • Maintains mechanical integrity under high loads and shock.
2. Wear Resistance:
   • Chromium and molybdenum improve surface wear resistance, ideal for high-friction applications.
3. Hardenability:
   • Provides uniform hardness in larger cross-sections.
4. Fatigue Resistance:
   • Performs well in applications involving cyclic loading.
5. Versatility:
   • Adapts to various heat treatments, enabling tailored mechanical properties.

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Applications of 42CrMo4 / 1.7225 Steel

42CrMo4 is extensively used in high-performance applications across multiple industries:

• Automotive Industry:
  • Gears, axles, crankshafts, and connecting rods.
• Aerospace:
  • Landing gear, structural parts, and engine components.
• Machinery Manufacturing:
  • Hydraulic cylinders, spindles, and machine tool components.
• Oil and Gas Industry:
  • Drill collars, rotary shafts, and high-pressure equipment.
• Construction Equipment:
  • Pins, bushings, and heavy-duty components.

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Heat Treatment of 42CrMo4 Steel

Heat treatment processes allow 42CrMo4 to achieve the desired balance of strength, hardness, and toughness:

1. Annealing:
   • Heated to 740–770°C, followed by slow cooling to improve machinability and reduce hardness.
2. Normalizing:
   • Heated to 840–880°C and air-cooled, refining the grain structure for enhanced toughness.
3. Quenching and Tempering:
   • Quenched at 820–860°C in oil or water, followed by tempering at 540–680°C to achieve high strength and toughness.
4. Nitriding:
   • Surface hardening at 500–550°C improves wear resistance and fatigue strength without altering the core properties.
5. Stress Relieving:
   • Performed at 550–650°C to reduce residual stresses after machining or welding.

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Processing Techniques

1. Machining:
   • Best machined in annealed or normalized conditions. Carbide or high-speed steel tools are recommended for hardened states.
2. Welding:
   • Preheating to 200–300°C and post-weld stress relief are necessary to avoid cracking.
3. Cold Working:
   • Limited due to high strength; suitable for minor forming operations.
4. Forging:
   • Performed at 1,000–1,200°C, followed by air cooling or normalizing.

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Comparisons with Similar Grades

Steel Grade	42CrMo4 (1.7225)	AISI 4140	EN 19
Carbon Content	Medium (0.38–0.45%)	Medium (0.38–0.43%)	Medium (0.36–0.44%)
Chromium Content	0.90–1.20%	0.80–1.10%	Similar
Molybdenum Content	0.15–0.30%	0.15–0.25%	Similar
Applications	High-stress parts	General engineering	High-performance parts

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Certifications and Standards

42CrMo4 steel adheres to multiple international standards:

• DIN EN 10083-3: Steels for quenching and tempering.
• ASTM A829: Structural alloy steel.
• SAE J404: Chemical compositions for alloy steels.

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