Available Shapes
420 Tool Steel
SS420 / SUS 420 / 1.4021 / UNS S42000 steel stockholders and suppliers, delivering to the whole of the Middle East. Nifty Alloys LLC are suppliers of 420 stainless tool steel in round bar, flat bar and plate in full lengths or bandsaw cut. 420 is a chromium alloyed stainless plastic mould steel, which is characterised by good polishability, good hardenability with high hardness achievable after heat treatment. The steel has fair corrosion resistance giving this plastic mould stainless steel grade suitability for applications requiring good hygiene in industries such as medical and optical.
Related Specifications
AISI ASTM A681 DIN 17350 BS EN ISO 4957
Applications
Typical Analysis
Forging
Annealing
Stress Relieving
Hardening
Tampering
Applications
420 stainless steel is ideally suited for plastic moulds, acid aggressive plastics, PVC or acetates and can be used with plastics containing abrasive fillers. 420 is suitable to produce components for medical and optical applications where a high surface finish is required.
Typical Analysis
Carbon | 0.40% | Silicon | 0.75% |
Manganese | 0.50% | Chromium | 13.50% |
Forging
420 plastic mould stainless steel can be forged by heating slowly and uniformly to 1000°C. After forging cool slowly in furnace or thermoinsulating material.
Annealing
420 is commonly supplied in the annealed condition. Re-annealing will only be necessary if the steel has been forged or hardened. To anneal heat slowly to 780°C. Cool slowly in furnace to 600°C and then cool in air.
Stress Relieving
When heavy machining or grinding of 420 plastic mould stainless steel has been carried out it is advisable to stress relieve in order to minimise the danger of distortion or cracking during the subsequent heat treatment. To stress relieve, heat the tools slowly to 650°C, soak for a minimum of two hours per 25mm of section and allow to cool down in the furnace to 500°C then continue to cool freely in air. The tools can then be finish machined, leaving on an allowance for final grinding after hardening and tempering.
Hardening
Pre heat the 420 stainless steel to 600-700°C until heated through. Continue heating the 420 to the final hardening temperature of 980-1050°C ensuring that the component is heated through. Protect the 420 component against decarburisation by using a neutral salt bath, controlled atmosphere furnace or vacuum. Air cool or quench in oil.
Tampering
Heat uniformly and thoroughly to the selected tempering temperature and hold at heat for one hour per 25mm of total thickness. Double tempering is recommended. To achieve the best permutation of hardness, toughness and corrosion resistance it is recommended to temper at 250°C.
Temperature [°C] | 100 | 200 | 300 | 400 | 500 | 600 |
Hardness [HRc] | 56 | 54 | 52 | 54 | 53 | 34 |