Brief Introduction of 38CrMoAl Special Nitriding Alloy Structural Steel

38CrMoAl is a classic Chinese special aluminum‑containing nitriding steel under GB/T 3077 standard. Alloyed with Cr‑Mo‑Al elements, it is designed specifically for gas nitriding treatment. After quenching‑tempering pre‑treatment followed by nitriding, the workpiece achieves extremely high surface hardness, excellent wear‑resistance and fatigue performance, while the core retains good strength and toughness. Nitriding deformation is minimal, making it ideal for high‑precision mechanical components. It is supplied as hot‑rolled black round bars, precision bright bars, plates and forged blanks, widely used in machine tools, hydraulic, plastic extrusion and general heavy‑duty machinery industries.

Table 1: Chemical Composition of 38CrMoAl (Mass Fraction, wt.%)

表格

Table 2: International Equivalent Grades of 38CrMoAl

表格

Heat Treatment & Key Performance

Standard pre‑treatment: Quench at 930‑950 ℃ (oil cooling) + high‑temperature tempering at 620‑680 ℃. Tempered mechanical properties: tensile strength ≥980 MPa, yield strength ≥835 MPa, hardness HB 260‑320 with good core toughness抖音百科. Subsequent gas nitriding at 500‑540 ℃: surface hardness reaches HV 900‑1200 (equivalent to HRC 68‑72), effective nitriding depth 0.3‑0.6 mm. It keeps high surface hardness below 500 ℃ without temper softening, with very small dimensional change after nitriding. Limitation: Nitrided layer possesses certain brittleness, not suitable for parts subjected to heavy impact loads; poor welding performance, welding requires pre‑heating and slow cooling.

Main Application Fields

1. Machine‑tool precision components: High‑precision spindles, boring bars, lead screws, worms and gear shafts requiring low‑deformation nitriding treatment.
2. Hydraulic & pneumatic industry: Hydraulic cylinder piston rods, valve bodies, valve spools and high‑pressure pump shafts with wear‑resistant surface and tough core.
3. Plastic & rubber extrusion machinery: Extruder screws, barrel liners and wear‑resistant sleeves for plastic injection and extrusion equipment.
4. Power & general machinery: Cylinder liners, high‑pressure valve parts, nitrided gear blanks and measuring tool components under medium‑load friction conditions.

38CrMoAl features fast nitriding speed, stable surface hardness and controllable tiny deformation. It is the most widely‑used domestic nitriding steel for high‑precision wear‑resistant mechanical parts, well‑accepted by machinery manufacturers globally.

5 HD Matching Pictures (800×800 square for product page)

1. Stacked hot‑rolled black‑skin 38CrMoAl round bars in factory warehouse
2. Cross‑section close‑up of 38CrMoAl black bar with mill test certificate label
3. Precision ground bright 38CrMoAl alloy steel bar with smooth surface
4. Rough‑machined spindle blank manufactured from 38CrMoAl raw material
5. Finished nitrided hydraulic piston rod processed from 38CrMoAl steel