Technical Information - Heat Treating
Process Capabilities
Air Hardening
We have two modern computer controlled Abar Ipsen vacuum furnaces for austenitising air-hardening steels.
Our furnaces use convection assisted heating and directional quenching to increase temperature uniformity and minimise distortion. Both furnaces are computer controlled and data-logged for consistency and tracability.
Commonly Air Hardened Materials
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D2, H13, 400 Series Stainless Steel, A2, Calmax, 2767 - EN30b, A6, High Speed Steel, CPM3V, CPM4V, CPM10V, CPM15V, Vanadis 4, Vanadis 10.
Maximum Sizes
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Vacuum Furnace Number One - 900 mm width x 1,200 mm length x 600 mm height, 1,100 kg maximum load.
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Vacuum Furnace Number Two - 650 mm width x 1,000 mm length x 500 mm height, 500 kg maximum load.
Turnaround Times
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D2, 420, Stavax - Allow 2 days.
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H13 - Allow 3 days.
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High Speed Steel, CPM - Weekends Only.
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2767, K600 - Allow 5 days.
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A2, Calmax - Allow 5 days.
Aluminium Treatment
Some aluminium alloys can be solution treated and/or age hardened to increase strength and machinability. HTL use a dual drop bottom oven specifically designed for the solution treatment of aluminium. Features include: computer control and data logging, hot or cold water quench, 5 second quench delay.
Common Tempter Designations
Commonly Treated Materials
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2014, 2024, 6060, 6061, 6063, 6351, 7075, 7079, CC601, LM25, LM13.
Maximum Sizes
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Solution Treatment - 650 mm width x 1,000 mm length x 1,000 mm height, 700 kg maximum load.
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Age Hardening - 1,200 mm width x 2,800 mm length x 1,200 mm height, 3,000 kg maximum load.
Turnaround Times
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Typically 3-4 days, however a faster turnaround can be arranged for urgent work.
Black Corrosion Resistant Nitriding (NITREG® + ONC®)
Very hard, corrosion resistant, and an aesthetically pleasing black
Heat Treatments Ltd is pleased to be able to offer the Nitreg®+ONC® process to the New Zealand market. As part of our technology agreement with Nitrex Metal Inc we have been working hard at developing and proving this sought after treatment here in our Auckland plant.
For applications where resistance to atmospheric corrosion and an attractive dark finish is desirable, the Nitreg® nitride plus ONC® is the appropriate process. The objective with this treatment is to transform the very top portion of the nitride white layer into a complex spinel structure consisting mostly of Fe3O4 iron oxide.
Such a post-nitriding oxidation treatment has an effect of enhancing the corrosion resistance of an already nitrided component while giving the surface an attractive dark finish, which is expressly desired by many customers.
ONC®, applied in combination with the Nitreg® potential-controlled nitriding or Nitro-carburising process is a clean technology that in many instances can replace chrome plating and salt bath nitriding with their inherent problems of pollution and cost.
Depending on the type of steel, parts treated with the Nitreg®+ONC® process can easily pass well over 200 hours of salt-spray test as per ASTM B117 before the first corrosion spot appears.
Advantages of ONC®
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Improved corrosion resistance of up to 400 hours of regular usage
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Inherent wear resistance
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Attractive black surface finish
Advantages Compared to Hard Chrome
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More wear resistant than hard chrome.
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Cannot flake off like hard chrome. No adhesion issues as it's not a coating.
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Uniform layer thickness (hard chrome can't go down deep holes or bores etc).
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More resistant to dents and bruising than hard chrome due to the diffusion layer below.
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Can be done on most steels & cast irons - MS, 1040, 4140, cast iron.
Turnaround Times
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Most common items will be processed during a weekend only run.
Carbonitriding
Carbonitriding is a surface hardening treatment similar to carburising, however carbon and nitrogen are diffused into the surface of a low alloy/low carbon steel. This results in a component with a hard, wear resistant surface and a softer, tough core. Carbonitriding is more suitable for plain carbon and mild steels.
We carbonitrides by the gaseous method, using computer controlled sealed-quench furnaces. Extremely tight control of carbon concentration, diffusion rates and temperature are required to process a component with minimum distortion and achieve optimum mechanical properties. The controlled atmosphere sealed-quench furnace is the most proven and respected method of producing high quality carbonitriding.
Commonly Carbonitrided Materials
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Mild Steel, 1020, 1040, 1045, Carbon Hollow Bar.
Maximum Sizes
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620 mm width x 950 mm length x 470 mm height.
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1,000 kg maximum load.
Turnaround Times
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Allow 3 days for general work. Extraordinarily large pieces or deep case depths may take longer. A faster turnaround can be organised for urgent work.
Carburising
Carburising is a surface hardening treatment in which carbon is diffused into the surface of a low alloy/low carbon steel. This results in a component with a hard, wear resistant surface and a softer, tough core.
We carburises by the gaseous method, using computer controlled sealed-quench furnaces. Extremely tight control of carbon concentration, diffusion rates and temperature are required to process a component with minimum distortion and achieve optimum mechanical properties. The controlled atmosphere sealed-quench furnace is the most proven and respected method of producing high quality carburising.
Commonly Carburised Materials
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8620, 9310, EN36A, EN39B, 1.2764, E230, E200, E110, Impacto, Super Impacto, Carbon Hollow Bar.
Maximum Sizes
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620 mm width x 950 mm length x 470 mm height.
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1,000 kg maximum load.
Turnaround Times
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Allow 3 days for general work. Extraordinarily large pieces or deep case depths may take longer. Faster turnarounds can be arranged for urgent work.
Cryogenic Tempering
Cryogenic tempering is a heat treatment in which the material is cooled to cryogenic temperatures to the order of -185°C, usually using liquid nitrogen. It has been shown to increase strength and hardness in some circumstances, sometimes at the cost of toughness. Whilst the cryogenic process is a relatively new discovery, there is evidence that most tool steels will demonstrate an increase in wear resistance after cryogenic processing. This treatment is more suitable for tool steels, high-carbon and/or high-chromium steels where the absolute maximum possible wear resistance is the primary requirement.
We use a liquid nitrogen cooled cryogenic chamber, built in-house.
Commonly Cryogenically Treated Materials
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D2, A2, HSS, other high alloy steels and carburising grades.
Maximum Sizes
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900mm width x 1300mm length x 1000mm height.
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800kg maximum load.
Turnaround Times
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Quite variable at the moment, please phone for details.
Induction Hardening
Induction hardening is a localised surface hardening treatment, usually performed on round components. The surface of the component is heated by electromagnetic induction and then quenched to produce a hard surface. The advantages of induction over other types of surface hardening are many: less distortion as only localised heating, no masking required, fast, deep case depths greater than 8mm. Induction is ideal for excavator pins, conveyer chain pins, splined shafts and axles, guide pins, etc.
We have now commissioned a twin-spindle CNC-controlled induction hardener. The twin spindles allow processing of two pins simultaneously to reduce the turn around time and processing cost of larger batch size jobs. CNC control provides high tolerance repeatability.
Commonly Induction Hardened Materials
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1040 - 1060, 4140, 4340, P20, 2767.
Maximum Sizes
Turnaround Times
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Typically 2 days, however a faster turnaround can be arranged for urgent work.
Metallurgical Services
To maintain our high quality standards we operate a modern well equipped metallurgical laboratory.
Available Services
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Metallurgical consultation.
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Failure analysis.
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Material and heat-treat recommendations.
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Hardness testing - on site and portable.
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Spectrographic analysis.
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Mag particle crack testing.
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Certification, release notes, reports.
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Digital microscopy available.
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Leco microhardness tester with digital facility.
Nitriding
Nitriding is a low temperature/low distortion surface hardening treatment that greatly improves wear resistance and other mechanical properties of most types of steels.
We use the patented Nitreg nitriding process. The Nitreg process is a computerised nitriding system where the nitriding potential of the furnace atmosphere is controlled. The nitriding potential has a direct relationship to mechanical properties and accurately controlling this gives us many advantages over conventional nitriding techniques
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Lower distortion levels.
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Results are predictable and repeatable.
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No brittleness of the white layer.
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Process times are reduced.
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Better uniformity of layer, regardless of geometry.
With the Nitreg system the recipe is adjusted to optimise case properties depending on the material and application or requirements.
Commonly Nitrided Materials
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P20, H13, D2, O1, 4140, 4340, 1040, 1045.
Maximum Sizes
Turnaround Times
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Most common items will be processed overnight, extraordinarily large pieces or deep case depths may take longer. Urgent jobs should be arranged in advance.
Oil Hardening
We oil harden in computer controlled sealed-quench furnaces, both the austenitising and the quench process is carried out in a controlled atmosphere to prevent oxidation or de-carb.
Commonly Oil Hardened Materials
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4130, 4140, 4340, 1050 - 1070, O1, S1, S5, EN30b, EN45.
Maximum Sizes
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620 mm width x 950 mm length x 470 mm height.
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1,000 kg maximum load.
Turnaround Times
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Allow 3 days, urgent jobs should be organised in advance.
Stress Relieving
Stress relieving is used to reduce residual stresses that may remain in a component as a consequence of welding, forming, machining, etc.
Stress relieving is performed to: facilitate further forming/machining, improve as-welded properties or to reduce distortion that may result during later heat-treatment.
Our stress relieving furnaces are computer controlled/data logged and have programmable heating and cooling rates.
Commonly Stress Relieved Materials
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Mild steels, Tensile steels, Tool steels, Aluminium, Titanium, Incolloy.
Maximum Sizes
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1,260 mm width x 3,000 mm length x 1,260 mm height.
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3,000 kg maximum load.
Turnaround Times
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Allow 2 days, however extraordinarily large jobs may take longer.
