24 July 2021 Structural Steel Bar
AISI 4145H Structural Steel Bar
AISI 4145H is a hardenable alloy structural steel, which is equivalent to 45CrMnMo steel or 40CrMo steel in Chinese standards. AISI 4145 is a chromium molybdenum low alloy steel grade widely used in the oil and gas sectors but with a higher carbon content compared with AISI 4140. Larger diameters AISI 4145 bars are often supplied with higher Molybdenum level, 0.35% max.
AISI 4145H is the upgraded type of AISI 4145. AISI 4145H has improved hardenability and is commonly used in the high strength condition with min.110 KSI yield and suitable for downhole drilling tools such as subs, x-overs, drill collars, pup-joints and fishing tools. General engineering applications include components exposed to heavy strain, such as shafts, gear, bolts etc. AISI 4145H can also be used in hardened condition as machine parts exposed to heavy wear.
Chemical Composition:
| C(％) | Si(％) | Mn(％) | P(％) | S(％) | Cr(％) | Ni(％) | Cu(％) |
|---|---|---|---|---|---|---|---|
| 0.42～0.49 | 0.65 ~ 1.10 | 0.75 ~ 1.20 | ≤0.035 | ≤0.040 | 0.15～0.25 | 0.15 ~ 0.30 | ≤0.25 |
Mechanical Propoerties:
| Yield Strength Rp0.2(MPa) | Tensile Strength Rm(MPa) | Elongation δ5 (%): | Reduction of area ψ (%): | Impact energy Akv (J): | Impact toughness value αkv (J/cm2) | Hardness |
|---|---|---|---|---|---|---|
| ≥ 758(85) | ≥ 965(95) | ≥ 14.5 | ≥ 45 | ≥ 41 | ≥ 39(4) | ≥ 285 HB |
Heat Treatment:
Forging:
Preheat the steel carefully, then raise the temperature to 1150-1200°C for forging. Do not forge below 850°C. AISI 4145 has good forging characteristics but care must be taken when cooling the steel due to its susceptibility to cracking.
Annealing:
Heat the steel slowly to 800-850°C and allow enough time for the steel to be thoroughly heated. Cool slowly in the furnace to 480°C followed by air cooling.
Harding:
AISI 4145 steel is usually supplied ready heat treated to 30-36HRc. If further heat treatment is required annealed AISI 4145 should be heated slowly to 840-875°C and after adequate soaking at this temperature quench in oil. Temper as soon as the tools reach room temperature.
Tempering:
Heat carefully to a suitable temperature selected by reference to a tempering chart or table (usually between 550-700°C, soak at the temperature for 2 hours per 25mm of ruling section, then allow to cool in air. Tempering between 250-375°C is not advised as tempering within this range will seriously reduce the impact values of this steel.
Applications:
AISI 4145H is a low alloy steel suitable for downhole drilling tools such as subs, x-overs, drill collars, pup-joints and fishing tools. General engineering applications include components exposed to heavy strain, such as shafts, gear, bolts etc. AISI 4145H can also be used in hardened condition as machine parts exposed to heavy wear.
Equivalent Grade:
- EN 1.7225
- ASTM A255
- UNS G41450
- AISI 4145H Modified