23-05-2021, 12:52 PM
Hi
I have only just read the latest entries to this topic.
I am a toolmaker by trade and have worked in the automotive press tool industry and Plastic mold making until teaching engineering in the last 10 years.
my knowledge of metallurgy and heat treatment tells me that although 4140 is a nitridable high tensile steel ,it is not however regarded as a nitriding special steel. Those materials invariably contain aluminium in small concentrations.
One trade name for this was Nitralloy and I think it was developed during WW2. It exhibits superior characteristics to 4140 and is fine grained
So I believe there are better alternatives to 4140 (EN40b). In New Zealand 4140 is only available in rounds so it cant be used for flat billet cranks here.
P20 is the modern plastic die steel of this aluminium alloyed nature, used in industry for plastic molds and manufacture of stressed parts including crankshafts and gears among others, it is supplied in a heat treated stress relieved condition which means it is able to be sawn and milled/turned in a toughened state and ready for nitriding once machined and ground.
it is usual to polish the journals after the nitriding operation. it is around 60 tons tensile in this state and the hardness of the surface 63 Rockwell C plus.
A piece of this material of the dimensions required is around $160 NZ or 80 pounds UK.
I am certain of its availability in UK (West Yorkshire Steel Has it in stock in plate form - 45mm thick heat treated and stress relieved).
Heat treatment does not mean hardened ,but heated until it is tough and machinable and stable after machining.
I hope this is useful and would be interested if other engineers agree with my opinions on this.
Cheers Steve Hainsworth, Wellington NZ
I have only just read the latest entries to this topic.
I am a toolmaker by trade and have worked in the automotive press tool industry and Plastic mold making until teaching engineering in the last 10 years.
my knowledge of metallurgy and heat treatment tells me that although 4140 is a nitridable high tensile steel ,it is not however regarded as a nitriding special steel. Those materials invariably contain aluminium in small concentrations.
One trade name for this was Nitralloy and I think it was developed during WW2. It exhibits superior characteristics to 4140 and is fine grained
So I believe there are better alternatives to 4140 (EN40b). In New Zealand 4140 is only available in rounds so it cant be used for flat billet cranks here.
P20 is the modern plastic die steel of this aluminium alloyed nature, used in industry for plastic molds and manufacture of stressed parts including crankshafts and gears among others, it is supplied in a heat treated stress relieved condition which means it is able to be sawn and milled/turned in a toughened state and ready for nitriding once machined and ground.
it is usual to polish the journals after the nitriding operation. it is around 60 tons tensile in this state and the hardness of the surface 63 Rockwell C plus.
A piece of this material of the dimensions required is around $160 NZ or 80 pounds UK.
I am certain of its availability in UK (West Yorkshire Steel Has it in stock in plate form - 45mm thick heat treated and stress relieved).
Heat treatment does not mean hardened ,but heated until it is tough and machinable and stable after machining.
I hope this is useful and would be interested if other engineers agree with my opinions on this.
Cheers Steve Hainsworth, Wellington NZ