In-House Surface Finishing
Shivam Forge provides in-house surface treatment services for forged components — shot blasting to Sa 2.5, zinc electroplating (8–25 μm), manganese phosphate (5–15 μm), zinc phosphate, black oxide (Fe₃O₄), and passivation for stainless steel per ASTM A967/A380. Single-source supply from forging to finished surface with XRF thickness verification and salt spray testing per IS 11776.
Surface treatment is not a cosmetic step — it determines corrosion life, wear resistance and paint adhesion in service. At Shivam Forge, surface finishing is integrated into our manufacturing process, not outsourced. This means the same quality system that governs your forging also governs its surface treatment. You receive a single supplier, a single quality record and a single point of accountability.
Steel shot or grit blast to Sa 2.5 cleanliness grade per ISO 8501-1 — the standard pre-treatment before painting, phosphating or zinc plating. Removes mill scale, rust and forging oxide completely. Surface profile Ra 25–75 μm provides mechanical anchor for coatings.
Alkaline or acid zinc electroplating to IS 1573, depositing 8–25 μm zinc per requirement. Passivation options: clear (Fe0), yellow iridescent (Cr6-free trivalent), black passivation. Salt spray resistance: clear 96 hr, yellow 120 hr, black 72 hr minimum per IS 11776.
Manganese phosphate coating 5–15 μm (Mn₃(PO₄)₂) for internal wear surfaces, gears, shafts and bushes. Dark grey-black appearance. Post-treatment oil impregnation reduces initial break-in wear and provides mild corrosion protection. Used extensively in automotive and agricultural equipment forgings.
Zinc phosphate pretreatment (3–10 μm) before wet painting or powder coating. Converts the steel surface from oxide to phosphate crystals, providing superior paint adhesion and under-film corrosion resistance compared to shot-blasted steel alone.
Hot black oxide (magnetite, Fe₃O₄) conversion coating 1–2 μm thickness for mild corrosion protection and decorative appearance. Applied at 135–145°C in alkaline oxidizing salt bath. Post-treatment oil or wax provides additional corrosion protection. Common for fasteners, bushes and small forgings.
Citric acid or nitric acid passivation per ASTM A967 or ASTM A380 to restore the passive oxide layer on stainless steel forgings disturbed by machining, grinding or welding. Removes free iron contamination. Verified by copper sulfate test or high-humidity test per ASTM A967.
Fischer X-RAY XRF thickness gauge used for non-destructive zinc plating thickness measurement. Reports actual μm thickness at minimum 5 points per component. Ensures plating is within specified tolerance before dispatch.
Neutral salt spray (NSS) testing per IS 11776 / ASTM B117 for zinc-plated and phosphated components. Sample components from each batch tested at 35°C, 5% NaCl solution. White rust (zinc corrosion) and red rust (base metal corrosion) hours recorded and reported.
Cross-cut adhesion test per ISO 2409 for paint and powder coat adhesion on phosphated or blasted substrates. Rating 0 (no peeling) is required for acceptance. Batch-by-batch testing on coated sample panels.
100% visual inspection for blistering, bare spots, burning, hydrogen embrittlement cracks and passivation uniformity. Forgings with localized bare areas or uneven passivation colour are rejected for re-treatment.
High-strength forgings (hardness above 34 HRC / 320 HBW) are baked at 190–210°C for minimum 4 hours within 4 hours of zinc plating to relieve hydrogen embrittlement per IS 1573 and ASTM B633 requirements.
Manganese phosphate on gears, shafts and axle components. Zinc plating with yellow passivation on fasteners, brackets and brake hardware. Consistent coating on high-volume automotive forgings with batch-by-batch salt spray testing.
Shot blasting + zinc phosphate + paint primer for tillage tools, PTO shafts and implement linkage forgings. Extended outdoor corrosion protection critical for agricultural equipment stored in field conditions.
Black oxide for bushes, pins and small forgings requiring mild corrosion protection and professional appearance. Manganese phosphate for wear-resistant surfaces on pump shafts, guide pins and sliding components.
Zinc plating (12–15 μm, clear passivation) on hydraulic cylinder end caps, valve bodies and pneumatic fittings. Tight plating thickness control to maintain thread tolerances on plated fasteners and fittings.
Citric acid passivation per ASTM A967 for SS304, SS316 and SS316L food processing, dairy and pharmaceutical forgings. Removes free iron from machined surfaces and restores the full corrosion resistance of stainless steel.
Shivam Forge offers integrated surface treatment services for forged components at our Rajkot, Gujarat facility — eliminating the quality risks and logistics delays of outsourced finishing. Our in-house capability covers the full process chain: shot blasting to Sa 2.5 cleanliness per ISO 8501-1, zinc electroplating (8–25 μm per IS 1573), manganese phosphate (5–15 μm), zinc phosphate primer, black oxide and passivation for stainless steel per ASTM A967. Coating thickness is verified by Fischer XRF measurement and reported per batch.
Zinc electroplating at Shivam Forge is available in three passivation options — clear (Fe0 blue-silver), yellow iridescent (trivalent Cr6-free) and black — to match customer aesthetic and corrosion-resistance requirements. For high-strength forgings above 34 HRC, we perform mandatory hydrogen embrittlement relief baking at 190–210°C for 4 hours per IS 1573. Salt spray testing per IS 11776 is conducted on sample components from each batch, with results reported on our quality certificate.
Manganese phosphate coating is the preferred surface treatment for wear-critical internal surfaces — gear teeth, shaft journals, piston rods and sliding pins. The manganese phosphate layer (Mn₃(PO₄)₂, 5–15 μm) creates a micro-porous surface structure that retains lubricating oil through capillary action, reducing the critical break-in wear phase. Post-treatment oil impregnation completes the process. This treatment is standard on agricultural, automotive and compressor forgings supplied by Shivam Forge.
Passivation of stainless steel forgings is often overlooked but critical for maintaining corrosion resistance. Machining, grinding and handling introduce free iron contamination onto the stainless surface, disrupting the passive chromium oxide layer and creating rust spots in service. Our citric acid passivation per ASTM A967 removes this free iron and restores full corrosion resistance. We verify passivation effectiveness using the copper sulfate test — a simple but definitive check that free iron has been removed.
The commercial advantage of Shivam Forge's integrated finishing is measurable in your supply chain. Eliminating an external plating or shot-blasting vendor removes 3–5 days from your lead time, reduces inbound inspection of sub-supplier quality and eliminates the freight cost of a round-trip to a finishing vendor. Contact us at +91-9265772827 or sales@shivamforge.com for a complete quotation covering forging, heat treatment and surface treatment as a single supply.
We offer shot blasting (Sa 2.5 per ISO 8501-1), zinc electroplating (8–25 μm per IS 1573) with clear/yellow/black passivation, manganese phosphate (5–15 μm), zinc phosphate, black oxide (Fe₃O₄) and passivation for stainless steel per ASTM A967/A380. Hard chrome plating is coordinated through a trusted external vendor.
Manganese phosphate provides superior wear resistance for metal-to-metal contact surfaces — gears, shafts and sliding components. It creates a micro-porous surface that retains oil, reducing break-in wear. Zinc plating is better for corrosion protection in atmospheric or wet environments where the component does not experience sliding contact.
Our zinc electroplating achieves minimum 96 hours to white rust and 240 hours to red rust with clear passivation (8 μm minimum), 120 hours white rust with yellow trivalent passivation, and 72 hours with black passivation — all per IS 11776 neutral salt spray test. Actual values are reported per batch test.
We use a Fischer XRF gauge for non-destructive zinc plating thickness measurement. We test minimum 5 points per component for critical components and report actual thickness in μm. For high-volume automotive batches, statistical sampling per IS 1573 Annexure applies.
During acid zinc plating, nascent hydrogen can be absorbed into high-strength steel and cause delayed fracture (hydrogen embrittlement). For forgings with hardness above 34 HRC or 320 HBW, we perform a bake-out at 190–210°C for minimum 4 hours within 4 hours of plating, per IS 1573 and ASTM B633 requirements.
Yes. We supply forgings shot blasted to Sa 2.5, zinc or iron phosphated, and wet-painted with customer-specified primer in one continuous operation. This is standard for agricultural equipment and infrastructure forgings requiring long-term outdoor corrosion protection.
We use citric acid passivation per ASTM A967 (Method C) as the default, which is environmentally cleaner than nitric acid. For applications requiring nitric acid passivation (ASTM A380), this is available on request. Passivation is verified by copper sulfate test per ASTM A967.
When forging and surface treatment are sourced separately, quality issues at the interface — surface contamination, rust between processes, incompatible pre-treatment — are common and difficult to assign responsibility. Single-source supply from Shivam Forge eliminates these handoffs. One supplier, one quality system, one quality certificate.
Why Choose Shivam Forge
Shivam Forge delivers precision hot-forged components from our integrated Shapar, Rajkot facility — covering forging, CNC machining, heat treatment, and quality inspection under one roof.
