Stainless steel quirks (work hardening, welding, boundary wear)

?Likely causes

• It is sticky, work hardens easily, and has low thermal conductivity, so cutting force and cutting heat are highAgreed by 2+ makers^[1][2]
• When rubbed by the tool during cutting, the surface becomes hard, shortening the life of later operations (tapping, reaming)One maker^[2][3][4]
• High affinity with the tool grade, so welding, built-up edge, and rake face wear tend to occurAgreed by 2+ makers^[1][5][6]
• Because of work hardening, hand tapping is difficult, and machine tapping is recommendedOne maker^[7]
• Rubbing on the work-hardened layer tends to cause boundary wear, which causes burrsAgreed by 2+ makers^[1][8][5]
• The impact when sawtooth chips break tends to chip the cutting edgeOne maker^[1]
• By family, precipitation-hardening grades are the hardest to machine, followed by duplex and austenitic grades. SUS304 in particular work hardens easilyAgreed by 2+ makers^[1][2]

✓Fixes

Cutting conditions

• Do not reduce the feed too much (more rubbing advances work hardening)One maker^[3][9]
• Use a step amount for the tap drill hole of about 0.5 times the drill diameter as a guideline, and do not make it too fineOne maker^[3]
• In face milling, raise the cutting speed (180-200 m/min) so that centrifugal force throws the chips offOne maker^[10]
• For boundary wear, change the depth of cut with each passOne maker^[8][5]

Tool

• Use a sharp edge geometry with a large rake angle to reduce cutting force and temperatureOne maker^[1][10]
• Select heat-resistant tool materials and coated gradesAgreed by 2+ makers^[1][6]
• Drill the tap drill hole with a through-coolant carbide drill for stainless steel or a sharp HSS drillOne maker^[3]

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