Part A: General Topic
Properties of stainless steel
• Corrosion resistant
• Good tensile strength
• Good low and high temperature service
• Appearance
• Hygienic
• Has a respectable friction coefficient
Corrosion resistant
Stainless steel has a chromium-rich rust protective oxide thin film on the surface known as a passive layer, in which prevents corrosion by blocking oxygen diffusion to enter the passive layer and spreads rust into the internal material. As seen in Figure 1, stainless steel rather than forming a rust layer like other carbon steels, it produces an macroscopically invisible layer in which protects against rusting.
[2]
Figure 1: Stainless steel compared to other non-rust protection material
Given that there …show more content…
Other properties are:
• Cannot be heat treatment hardened
• Able to be hardened to high strength level whilst retaining a good level of ductility and toughness
• Depending on composition and work hardening they are generally non magnetic
• High hygienic properties in temperature changes
Martensitic→ has highest content of carbon of the group (1%) and thus are able to be hardened and tempered resulting in being used high strength (with sacrificial ductility and toughness properties) and moderate corrosion resistance (labelled as DSS 2205 in figure 4). Is magnetic.
Duplex → has a microstructure that generally contains 50% ferrite and 50% austenite which result higher strength than both groups. Has;
• Resistant to corrosion but with better strength and stress corrosion properties (Check Figure 4 for reference proof)
• Can be weld able but aided with correct welding consumables and heat input
• Moderate formability
• Low magnetic properties because of austenitic phase …show more content…
For that matter so does the other components but we will see into more detail. Taking in consideration the SAE 52100 raw material manufacturers follow this composition range: [11]
The manufacturing procedure specifically for the SAE 52100 are as follows [11]
Turning section
The rings (both inner and outer) are machined from forged rings with same material as the cage and balls. The set passes through a grinder which alters the rough dimension of the ring to the correct thickness. Later a gauge checks each width to the correct value as it exits the grinder so to separate the inner and outer ring from the same grinding process. This is done to grind each outer ring’s circumference on separate machines.
The outer ring enters the grinder which shapes its outer surface to a precise roundness and diameter. A coolant lubricant (water based liquid) prevents them from overheating which would cause warping. Then a gauge checks the diameter as it exits the grinding