The stainless steel on my refrigerator door, dishwasher is scratched. How can I remove the scratches?

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Scratches are difficult to remove. Most kitchen appliances, sinks, and counters have a polished finish with short directional polishing lines. Restoring a polished finish to its original appearance requires a professional such as a company that specializes in fabricating or polishing stainless steel. If the refrigerator or dishwasher door panel is replaceable, purchasing a new panel is normally more cost effective than professional refinishing. The homeowner may want to consider obtaining replacement panels with angel hair, distressed, swirl, or embossed finish. These finishes help to hide light scratching and can be obtained from companies that specialize in stainless steel finishes. Counters and appliance doors that are not easily removable must be refinished in place. When the counter is refinished, it may have long rather than short polishing lines. If a slightly different finish is acceptable and cost is a consideration, a homeowner can refinish the counter or appliance using a non-metallic abrasive pad such as a Scotch Brite® pad. This can be done by rubbing the surface with the pad using long uniform strokes in the same direction as the current polishing lines. This will not eliminate deep scratches. A professional may offer this finish as a less expensive option. The resulting finish is normally referred to as a hairline or long grain finish. Some appliance companies are starting to offer this finish.

What is the recycle content of stainless steel?

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Stainless steel can be recycled 100%. That is all stainless steel can be re-melted to made a new stainless steel. The typical amount of recycled stainless steel "scrap" that is used to make new stainless steel is between 65 & 80%.

What does the "L" designation mean?

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The use of the letter L after the grade number, i.e., 304L, means that the carbon content is restricted to a MAXIMUM of 0.03% (normal levels are 0.08% max. and in some grades can be as high as 0.15% max.). This lower level of carbon is usually used where "welding" will be performed. The lower level of carbon helps to prevent the chromium from being depleted (by forming chrome carbides at the weld site) and therefore allow it to remain over 10 ½% so it can form the "passive" oxide layer that gives stainless its corrosion resistance.

Can Stainless steel be "hardened"?

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YES. The 300 series stainless steel can be "hardened" BUT only by "work hardening." That is by cold working the material, either by cold rolling down to lighter and lighter gauges, or by "drawing" through a die or other size altering operation. "Annealing" stainless steel will REMOVE the work hardening effect. YES and NO. The 400 series have two different stainless steel structures. One is called "ferritic" (409, 430, 434. 439) which cannot be hardened by heat treatment. The other is called "martensitic" (403, 410, 416, 420, & 440 A,B,C) which CAN be hardened by heat treatment.

15-5 PH Stainless Steel

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15-5 PH Stainless Steel
Specification: AMS 5862, AMS 5659, AMS 5826, ASTM A 564, ASTM SA 564, ASTM A 693,ASME SA 693, ASTM A 705,ASME SA 705

15-5PH Precipitation Hardening Stainless Steel Alloy (S15500) is a variant of the older 17-4 PH (S17400) chromium-nickel-copper precipitation hardening stainless steel. Both alloys exhibit high strength and moderate corrosion resistance. High strength is maintained to approximately 600°F (316°C). The 15-5 PH alloy was designed to have greater toughness than 17-4 PH, especially in the through-thickness (short transverse) direction. This improved toughness is achieved by reduced delta ferrite content and control of inclusion size and shape. The composition and processing of 15-5 PH alloy is carefully controlled to minimize its content of delta ferrite, which is present in the 17-4 PH stainless steel material. Inclusion control is done by consumable electrode remelting using the electro-slag remelting (ESR) process. The 15-5 PH alloy is martensitic in structure in the annealed condition and is further strengthened by a relatively low temperature heat treatment which precipitates a copper containing phase in the alloy. Like the 17-4PH alloy, the 15-5 PH stainless steel alloy requires only a simple heat treatment; a one step process conducted at a temperature in the range 900°F (482°C) to 1150°F (621°C) depending on the combination of strength and toughness desired. A wide range of properties can be produced by this one step heat treatment. Heat treatment in the 900°F (482°C) range produces highest strength, although slightly less than those of semi-austenitic alloys like S17700 (17-7 PH) or S15700 (15-7 PH). The latter precipitation hardening alloys generally require more steps to complete heat treatment. The15-5 PH alloy is generally better-suited for plate applications than are the semi austenitic alloys.

MECHANICAL PROPERTIES PER 15-5 PH AMS 5659, AMS 5862

Temperature, °F	363 (Condition A)
Condition	H 900	H 1075	H 1150
0.2 Offset Yield Strength, ksi	170	125	105
Ultimate Tensile Strength, ksi	190	145	135
Elongation % in 2" minimum	10	13	16
Reduction of Area, %	35	45	50
Hardness, Brinell	388	331	277

AISI 347 Stainless Steel

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AISI 347 Stainless Steel Bar AMS 5646
UNS S34700
PDF: 347 Stainless Steel Bar

Nominal Composition

Iron 68%
Chromium 18%
Nickel 11%
Columbium+Tantalum 10 x Carbon minimum
Description

Type 347 is a columbium/tantalum stabilized austenitic chromium-nickel stainless steel which was developed to provide an 18-8 type alloy with improved intergranular-corrosion resistance. Type 347 is stabilized against chromium carbide formation by the addition of columbium and tantalum. Since columbium and tantalum have a stronger affinity for carbon than chromium, columbium-tantalum carbides precipitate within the grains instead of forming at the grain boundaries. Type 347 should be considered for applications requiring intermittent heating between 800ºF (427ºC) and 1650ºF (899ºC), or for welding under conditions which prevent a post-weld anneal.

Properties

Non-magnetic. The corrosion resistance of Type 347 stainless steel is similar to Type 304 stainless steel. Type 347 is used for welded equipment which cannot be annealed and for equipment which is operated between 800-1500°F (427-816°C). The elevated temperature stress rupture and creep strength of Type 347 are higher than Type 304 stainless steel. The room temperature yield strength and tensile strength are approximately 35,000 psi and 85,000 psi, respectively.

Hardness

The hardness of Aerodyne stock is typically 170 BHN and is supplied in the fully annealed condition. Type 347 is not hardenable through heat treatment, but small sections can be cold work hardened. Room temperature yield strength is typically 40,000 psi with tensile strength of 90,000 psi.

Machinability

RATING:
80% of B-1112

TYPICAL STOCK REMOVAL RATE:
90 surface feet/minute with high speed tools.

COMMENTS:
Type 347 machines with tough and stringy chips and has a high rate of work hardening and requires a rigid set-up, plenty of power and positive cuts. Use as heavy a cut as possible to prevent surface work hardening and glazing.

Density:

0.288 lbs/in3, 7.97 g/cm3

What is "passivation"?

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When the amount of chromium (in an iron matrix) exceeds 10 ½%, a complex chrome oxide forms instantaneously that prevents the further diffusion of oxygen into the surface and results in the "passive" nature of stainless steel and its resistance to oxidation (or corrosion). A chemical "dip" into 10% nitric acid plus 2% hydrofluoric acid bath will enhance the development of this "passive" oxide.

Is stainless steel magnetic?

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There are several "types" of stainless steel. The 300 series (which contains nickel) is NOT magnetic. The 400 series (which just contains chromium and no nickel) ARE magnetic.

Can stainless steel rust? Why?

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Stainless does not "rust" as you think of regular steel rusting with a red oxide on the surface that flakes off. If you see red rust it is probably due to some iron particles that have contaminated the surface of the stainless steel and it is these iron particles that are rusting. Look at the source of the rusting and see if you can remove it from the surface. If the iron is embedded in the surface, you can try a solution of 10% nitric and 2% hydrofluoric acid at room temperature or slightly heated. Wash area well with lots and lots of water after use. Commercially available "pickling paste" can also be used.

What is the difference between 18/8 and 18/10 stainless steel?

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The first number is the amount of chromium that is contained in the stainless, i.e., 18 is 18% chromium. The second number is the amount of nickel, i.e., 8 stands for 8% nickel. So 18/8 means that this stainless steel contains 18% chromium and 8% nickel. 18/10 is 18% chromium and 10% nickel. The higher the numbers the more corrosion resistant the material. 18/0 is a misleading designation. Both 18/8 and 18/10 contain nickel and are part of the grade family "300 series" stainless. 18/0 means that there is 18% chromium but zero nickel. When there is no nickel the stainless grade family is the "400 series". 400 series are not as corrosion resistant as the 300 series and are magnetic, where the 300 series are non-magnetic.

What makes stainless steel stainless?

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Stainless steel must contain at least 10.5 % chromium. It is this element that reacts with the oxygen in the air to form a complex chrome-oxide surface layer that is invisible but strong enough to prevent further oxygen from "staining" (rusting) the surface. Higher levels of chromium and the addition of other alloying elements such as nickel and molybdenum enhance this surface layer and improve the corrosion resistance of the stainless material.