440C Stainless steel is a type of modern steel and famous for its high corrosion resistant, wear resistance, strength and hardness qualities among all the stainless alloys, capable of attaining (after heat treatment) the highest hardness (60 HRC). It has good resistance to the atmosphere, fresh water and mild acids. It has best resistance in the hardened, tempered and passivated condition. It allows creating a smooth polished surface and Razor sharp edges. It is being used in rolling element bearings, valve seats, casters, ball bearings and valve parts.

 

420C is a martensitic stainless steel with 12% Chromium which is sufficient to give good corrosive resistance properties. .It’s best corrosive resistance is when hardened and surface is ground or polished. It has good ductility in the annealed condition but can be hardened up to 500HB (highest of the chromium grades) due to its excellent harden-ability, it is capable of getting hardened up to 56 HRC Rockwell or higher. Martensitic Grades are known for high hardness and allowances must be made for poor weld ability and usually allowances for a final harden and temper treatment. 420 steel is magnetic and welding is not recommended. Material will not pass the 72 hours salt bath test.

 

316 is Austenitic stainless steel with features similar to AISI 302/304/304L series, but they can be anti-magnetic and, above all, the addition of molybdenum offers greater chemical resistance, particularly in sulfuric acid concentration. All balls can be annealed and passivated. The most common applications include their use in the chemical, paper and textile industries (valves, pumps and bearings).

 

MATERIAL	C%	Si%	Mn%	P%	S%	Cr%	Mo%	Ni%	N
AISI440C	0.95-1.20	1	1	0.03	0.03	16.0-18.0	0.4-0.75
		max	max	max	max
AISI302	0.15max	1.01	2	0.045	0.03	17.0-19.0		8--10	0.1max
		max	max	max	max
AISI304	0.08max	1.02	2	0.04	0.03	17.0-29.0		8--10
		max	max	5max	max
AISI316	0.08max	1.03	2	0.045	0.03	16.0-18.0	2.0-3.0	10--14	0.1max
		max	max	max	max
AISI420	0.26--0.35	1.04	1	0.035	0.03	12.0-14.0
		max	max	max	max