Comparison centre

Metal Finishing and Material Comparisons

Choose materials, processes, colours and test criteria from the decisions engineering, purchasing and QC teams make in real work.

Choose the decision you need to make

Each guide covers selection criteria, limits and links to the relevant tool or service.

S45C vs SCM440

S45C vs SCM440: which steel should you harden?

Compare S45C and SCM440 carbon, hardenability, HRC ranges, toughness, section-size effects and the information needed on a heat-treatment order.

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Black oxide vs Phosphate

Black oxide vs phosphate: which finish for screws, nuts and bolts?

Compare black oxide and manganese-zinc phosphate: thickness, colour, corrosion protection, oil retention, paint adhesion and what to specify on the order.

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Zinc plating vs Dacromet / zinc flake

Zinc plating vs Dacromet: which coating for screws and bolts?

Compare Cr3+ zinc electroplating and Dacromet/zinc flake: salt-spray hours, colours, hydrogen embrittlement risk, cost and how to specify each on an order.

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Grade 8.8 vs Grade 10.9 vs Grade 12.9

Grade 8.8 vs 10.9 vs 12.9 bolts: what actually differs?

Compare property classes 8.8, 10.9 and 12.9 per ISO 898-1: tensile strength, proof load, hardness, materials, quench & temper, hydrogen embrittlement and nut pairing.

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Case hardening vs Through hardening

Case hardening vs through hardening: which one for screws and bolts?

Compare carburizing (case hardening) and quench & temper (through hardening): materials, surface vs core hardness, case depth and how to choose for fasteners.

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Annealing vs Tempering vs Normalizing

Annealing vs tempering vs normalizing: which one does your part need?

Compare annealing, tempering and normalizing: temperatures, cooling method, resulting hardness and microstructure, where each fits in the process, and how to specify them.

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Carbonitriding vs Carburizing

Carbonitriding vs carburizing: which case-hardening for fasteners?

Compare carbonitriding and carburizing: temperature, case depth, diffused elements, distortion and how to choose for small low-carbon fasteners.

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Barrel plating vs Rack plating

Barrel plating vs rack plating: how small fasteners are actually plated

Barrel vs rack plating for screws, nuts, bolts and washers: thickness distribution, part size and weight limits, nesting and tangling, thread damage, cost per kg versus per piece, and when a part genuinely has to go on a rack.

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Quenching vs Tempering

Quenching vs tempering: two halves of one process

Quenching and tempering are not options you choose between. This page explains what each step changes in the steel, which one sets the final HRC, the ISO 898-1 minimum tempering temperature, and where the process goes wrong.

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SCM435 vs SCM440

SCM435 vs SCM440: one alloy step apart, and it shows

SCM435 versus SCM440 for fasteners: carbon content, attainable as-quenched hardness, hardenability by section size, property classes each realistically reaches, cold heading and quench-crack sensitivity.

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Class 10.9 vs Class 12.9

Class 10.9 vs 12.9: what you gain, and what you take on

Class 10.9 versus 12.9 per ISO 898-1: the real ~17% step in tensile and proof load, hardness ranges, the 425 °C and 380 °C minimum tempering temperatures, hydrogen embrittlement, ISO 4042 plating limits and ISO 15330 testing.

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Electroplated zinc vs Hot-dip galvanizing

Zinc plating vs hot-dip galvanizing: which one does your fastener need?

Electroplated zinc versus hot-dip galvanizing on fasteners: thickness, thread fit, 450 °C bath, property-class limits, corrosion life — and the jobs we send elsewhere.

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Zinc phosphate vs Manganese phosphate

Zinc phosphate vs manganese phosphate: match the coating to the job it does

Zinc versus manganese phosphate on fasteners: coating mass, oil retention, anti-galling, paint base, thread growth and which fastener suits each.

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Carburising vs Nitriding

Carburising vs nitriding: what a screw, nut or bolt actually gets

Carburising versus nitriding on small parts: temperature, surface hardness, case depth, distortion, cycle time — and why bulk fasteners get the carbon route.

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Zinc plating vs Zinc-nickel

Zinc plating vs zinc-nickel: when is the upgrade worth paying for?

Cr3+ zinc plating versus zinc-nickel on fasteners: corrosion, heat, contact with aluminium, embrittlement and cost — and why we do not run a Zn-Ni line.

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hardening

How Hard Can SCM440, SCM435 and S45C Get? Choosing a Steel Grade

S45C tops out near 50–58 HRC but is specified at 40–55 HRC in service. A 13-grade table for small parts separating the as-quenched ceiling from the after-temper value, plus which stainless grades harden at all.

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coloring

Zinc Plating Colour Chart: White, Blue, Yellow, Rainbow, Black, Green

The colour of zinc plating comes from the chromate passivation layer on top—it is not just looks; it also signals corrosion resistance. Here is the chart.

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plating

Zinc Plating vs Hot-Dip Galvanizing vs Chrome: Which to Choose

Compare electroplated zinc (Cr3+), hot-dip galvanizing and chrome plating on corrosion protection, thickness, cost and fit — with a buyer’s guide for screws, nuts and bolts.

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plating

Manganese vs Zinc Phosphate: Differences and When to Use Each

Phosphate comes in several types; the two main ones—manganese and zinc—differ in surface, colour and purpose. Here is which job suits which.

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testing

What Is HRC? Metal Hardness HRC, HV, HB with Conversion Table

HRC is the Rockwell C hardness scale, measured with a 120° diamond cone at 150 kgf and usable from about 20 to 65 HRC. Includes an HRC ↔ HV ↔ HB ↔ tensile conversion table and the reference values for each bolt property class.

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testing

Salt Spray Test (ASTM B117) — How to Read It

The salt-fog corrosion test: what the “hours” number means and how much to trust it.

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Metal Finishing and Material Comparisons

Choose the decision you need to make

S45C vs SCM440: which steel should you harden?

Black oxide vs phosphate: which finish for screws, nuts and bolts?

Zinc plating vs Dacromet: which coating for screws and bolts?

Grade 8.8 vs 10.9 vs 12.9 bolts: what actually differs?

Case hardening vs through hardening: which one for screws and bolts?

Annealing vs tempering vs normalizing: which one does your part need?

Carbonitriding vs carburizing: which case-hardening for fasteners?

Barrel plating vs rack plating: how small fasteners are actually plated

Quenching vs tempering: two halves of one process

SCM435 vs SCM440: one alloy step apart, and it shows

Class 10.9 vs 12.9: what you gain, and what you take on

Zinc plating vs hot-dip galvanizing: which one does your fastener need?

Zinc phosphate vs manganese phosphate: match the coating to the job it does

Carburising vs nitriding: what a screw, nut or bolt actually gets

Zinc plating vs zinc-nickel: when is the upgrade worth paying for?

How Hard Can SCM440, SCM435 and S45C Get? Choosing a Steel Grade

Zinc Plating Colour Chart: White, Blue, Yellow, Rainbow, Black, Green

Zinc Plating vs Hot-Dip Galvanizing vs Chrome: Which to Choose

Manganese vs Zinc Phosphate: Differences and When to Use Each

What Is HRC? Metal Hardness HRC, HV, HB with Conversion Table

Salt Spray Test (ASTM B117) — How to Read It

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