Forged Hollow Bar / Hollow Round Bar – Martensitic Stainless Steel 410 / 420 /

• Martensitic forged hollow round bar series: 410, 420, 431, 440C, compliant with ASTM A479 / A182 forging & seamless blank standards
• Fully hardenable via quenching + temper heat treatment to reach adjustable hardness & superior wear resistance
• Nickel-free low-cost raw material, all grades completely magnetic under all processing states
• 410 low-carbon martensite for general low-load pump & valve hollow blanks
• 420 medium-carbon grade balanced hardness & mild corrosion for mold & tool tubular parts
• 431 nickel-modified martensite with excellent toughness for high-pressure hydraulic hollow components
• 440C high-carbon molybdenum grade achieves max HRC58–62 for precision bearing hollow stock
• Seamless forged hollow structure eliminates heavy deep boring of solid bar, cuts machining cost
• Custom OD, ID, wall thickness, length & full CNC boring/turning per customer CAD/PDF drawings

This series martensitic forged hollow round bars are manufactured via open-die forging + radial piercing seamless forming process. All blanks are delivered in fully annealed soft state for easy CNC machining; customers can conduct custom quenching & tempering to achieve target hardness levels.

Without expensive nickel alloy elements, martensitic hollow bar has prominent price advantage compared to 304/316L austenitic hollow tubes. Four grades are tiered by carbon & nickel content to cover diversified industrial demands: low-carbon 410 for general mechanical hollow parts; medium-carbon 420 for mold and hardware tubular blanks; nickel-alloyed 431 for high-pressure hydraulic cylinder sleeves; ultra-high carbon 440C for precision bearing and measuring tool hollow stock. Seamless hollow design saves massive solid bar boring workload, widely machined into pump sleeves, hydraulic cylinder blanks, valve hollow bodies, bearing bushings and mold tubular components for machinery, mold, hydraulic and petroleum industries.

Low-carbon 13% chromium martensitic steel. Soft after full annealing, great machinability; moderate hardness after quenching & tempering, suitable for low-load pump sleeves, general valve hollow blanks and dry mechanical tubular parts.

Medium-carbon martensite with higher hardening capacity than 410. Balanced wear resistance & mild anti-rust performance, ideal mold holder hollow sleeves, kitchen hardware tubular stock and instrument hollow components.

Nickel-added martensitic stainless steel. Extra nickel greatly improves impact toughness under cyclic pressure, perfect high-pressure hydraulic cylinder hollow blanks and heavy-duty valve tubular parts.

Highest carbon martensite with molybdenum additive. Reaches extreme hardness up to HRC62 after heat treatment, outstanding abrasion resistance, premium hollow stock for precision bearing bushings and wear-resistant measuring fixtures.

• Martensitic Stainless Steel: 410,420,431,440A,440B,440C,416
• Ferritic Stainless Steel: 409,430,439,444
• Austenitic Stainless Steel: 304,316L,321,347,904L
• Duplex Stainless Steel: 2205,2507,S32750,F51,F55
• PH Stainless Steel:17-4PH,15-5PH,17-7PH
• Nickel Base Alloys: Monel400/K500, Incoloy825, Inconel600/625, Hastelloy C276
• Alloy & Carbon Steel: A105,4140,F22,F91,A516 Gr.70

No expensive nickel composition, far lower raw material cost than austenitic hollow tubes for dry & weakly corrosive industrial environments.

All martensitic grades can be hardened after CNC machining; 440C reaches HRC58–62 for extreme wear-resistant hollow parts.

Magnetic in all heat treatment states, ideal magnetic mechanical hollow sleeves and fixture blanks.

410 general machinery, 420 mold hardware, 431 high-pressure hydraulics, 440C precision bearings for one-stop material selection.

Pre-pierced hollow blank removes deep boring operation on solid bar, shortens processing cycle and reduces material waste.

• 410: Pump sleeve hollow blanks, general valve tubular bodies, low-load mechanical shaft sleeves
• 420: Mold holder hollow sleeves, hardware fixture tubular stock, light equipment hollow shafts
• 431: High-pressure hydraulic cylinder blanks, heavy-duty valve hollow components, marine pump sleeves
• 440C: Precision bearing bush hollow stock, measuring tool tubular parts, wear-resistant fixture blanks
• General: Oil well small hollow sleeves, machinery gear housing blanks, hydraulic piston tubular parts

We provide integrated open-die forging & radial piercing seamless hollow production, full CNC precision machining per customer CAD/PDF drawings:

• Custom fixed-length cutting, facing, inner & outer diameter turning, chamfering
• Precision boring, grooving, threading, internal & external grinding
• Fully annealed / Quench & temper custom heat treatment service
• Surface pickling, passivation finishing treatment

We supply martensitic forged hollow round bar for mold, hydraulic, machinery and petroleum global industrial clients.

• 100% UT + Eddy Current dual testing to detect forging lamination & internal bore defects
• Full batch tensile, yield & hardness mechanical performance inspection
• High-precision caliper & CMM for OD/ID/wall thickness tolerance control
• Spectrometer full spectrum chemical composition analysis per heat lot
• Metallographic martensite microstructure inspection after heat treatment

Mill Test Certificate EN 10204 3.1 can be issued and delivered with shipment documents before delivery.

• Inner: Plastic end caps + waterproof anti-rust plastic film full wrap for inner bore protection
• Outer: Reinforced fumigated wooden pallet with partition strips to avoid tube collision & scratch
• Custom heavy-duty export packaging available upon customer request

Normally 10 – 45 working days after receiving advance payment. Exact lead time depends on OD/ID wall size, order quantity and custom heat treatment/machining demands.