Difference Between 1.4301 1.4307 and 1.4541

1.4301 stainless steel is low carbon chromium nickel stainless and heat resisting steel somewhat superior to Type 302 in corrosion resistance.

1.4541 stainless steel is known as stabilized grades of stainless steel, is Chromium nickel steel containing titanium. Recommended for parts fabricated by welding which cannot be subsequently annealed. Also recommended for parts to be used at temperatures between 800°F and 1850°F (427 to 816°C), have good properties resistance to intergranular corrosion. The titanium element in 1.4541 stainless steel makes it more resistant to chromium carbide formation.

1.4541 stainless steel is basically from 1.4301 stainless steel. They different by a very very small addition of Titanium. The real difference is their carbon content. The higher the carbon content the greater the yield strength. 1.4541 stainless steel has advantages in high temperature environment due to its excellent mechanical properties. Compared with 1.4301 alloy, 1.4541 stainless steel has better ductility and resistance to stress fracture. In addition, 1.4307 can also be used for anti-sensitization and intergranular corrosion.

The real problem with most headers/upipes is a difference in the coefficient of thermal expansion (CTE) As you block gets hot it expands, as it cools it contracts. What you want is a material that expands and contracts at the same rate as your cast iron block. This allows the seals (gaskets/flanges) to undergo less stress. Most leaks (besides improper installation) are caused by this unmatched CTE. That is why stock exhaust manifold is cast iron, which really meany it has a 2% or more carbon content.

1.4541 = (17-19Cr, 9-12Ni + Titanium)

As for the dual designation theory, that is incorrect. L stands for low carbon.

1.4307 grade Low Carbon, typically 0.035% Max
1.4301 grade Medium Carbon, typically 0.08% Max

Carbide precipitation

The weld areas with temperatures 930°F – 1470°F are often called carbide precipitation zone – in which Chromium (Cr) combines with Carbon (C) and precipitates chromium carbides at the grain boundaries significantly reducing corrosion resistance of steel in this zone. One of the ways to combat this phenomenon is to lower the carbon content in steel to decrease the carbide precipitation – 1.4307 Stainless Steel is an example of such steel; the “L” in 1.4307 is for “Lower carbon” (.030% max vs. .080% max for 1.4301 steel). Even more effective way against carbide precipitation is addition of Titanium (Ti) to the alloy to “stabilize it”. The carbon is more attracted to the Titanium (Ti) and therefore it leaves the chromium alone. To be a true “stabilized” grade the 1.4541 steel has to have Titanium (Ti) content at least 5 times of Carbon’s (C). Reduced risk of corrosion in the HAZ is the main advantage of 1.4541.

Fatigue strength

In dynamic applications, fatigue strength is also important to consider. And in this respect 1.4541 Stainless Steel has a slight advantage over 1.4301 Stainless Steel. Fatigue or endurance limits (strength in bending) of austenitic stainless steels in the annealed condition are about one-half the tensile strength.Typical tensile and endurance limits for these alloys (annealed) are presented in the table below:

Alloy	Typical Tensile Strength	Typical Endurance Limit
1.4307	68 ksi	34 ksi
1.4301	70 ksi	35 ksi
1.4541	76 ksi	38 ksi

Temperature Factors
Tempearture factors could be another factor to consider in some aplications. As we can see in the table below the temperature redaction factors are slightly higher for 1.4541 than for 1.4307 at most elevated temperatures:

Temperature °F	1.4307 Factor	1.4541 Factor

70	1.00	1.00
150	0.95	0.97
200	0.91	0.95
250	0.88	0.93
300	0.85	0.91
350	0.81	0.89
400	0.78	0.87
450	0.77	0.85
500	0.77	0.83
600	0.76	0.80
700	0.74	0.76
800	0.73	0.68
900	0.68	0.59
1000	0.63	0.65
1100	0.58	0.59
1200	0.53	0.53

Difference Between 1.4301 1.4307 and 1.4541

Carbide precipitation

Fatigue strength

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