ASTM A194 Explained: Nut Grades, Chemical Composition, and Mechanical Requirements

ASTM A194 is a material specification specifically for nuts, and it is most commonly used together with ASTM A193 (bolts and studs) for high-temperature and/or high-pressure service.

ASTM A194 – Chemical Requirements

Carbon & Alloy Steel / Martensitic Stainless Steel Nuts

Grade	Material / Type	UNS	C	Mn	P	S	Si	Cr	Ni	Mo	Other / Notes
1	Carbon steel	—	≤0.15	≤1.00	≤0.040	≤0.050	≤0.40	—	—	—	—
2, 2HM, 2H	Carbon steel	—	≤0.40	≤1.00	≤0.040	≤0.050	≤0.40	—	—	—	—
3	Carbon-Molybdenum	—	0.40–0.50	0.70–0.90	≤0.035	≤0.040	0.15–0.35	—	—	0.20–0.30	—
4	Type 501	—	≤0.10	≤1.00	≤0.040	≤0.030	≤1.00	4.0–6.0	—	0.40–0.65	—
6	Type 410	S41000	0.08–0.15	≤1.00	≤0.040	≤0.030	≤1.00	11.5–13.5	—	—	—
6F	Type 416	S41600	≤0.15	≤1.25	≤0.060	≤0.15	≤1.00	12.0–14.0	—	—	Selenium 0.15 min
6F	Type 416Se	S41623	≤0.15	≤1.25	≤0.060	≤0.060	≤1.00	12.0–14.0	—	—	Selenium 0.15 min
7, 7M	4140 / 4142 / 4145	—	0.38–0.48	0.75–1.00	≤0.035	≤0.040	0.15–0.35	0.80–1.10	—	0.15–0.25	—
16	Cr-Mo-V steel	—	0.36–0.47	0.45–0.70	≤0.035	≤0.040	0.15–0.35	0.80–1.15	—	0.50–0.65	V 0.25–0.35, Al ≤0.015

Austenitic Stainless Steel Nuts

Grade	Material / Type	UNS	C	Mn	P	S	Si	Cr	Ni	Mo	Ti / Nb / N / Other
8, 8A	Type 304	S30400	≤0.08	≤2.00	≤0.045	≤0.030	≤1.00	18.0–20.0	8.0–11.0	—	—
8C, 8CA	Type 347	S34700	≤0.08	≤2.00	≤0.045	≤0.030	≤1.00	17.0–19.0	9.0–12.0	—	Nb+Ta ≥10×C, ≤1.10
8CLN, 8CLNA	Type 347LN	S34751	0.005–0.020	≤2.00	≤0.045	≤0.030	≤1.00	17.0–19.0	9.0–13.0	—	N 0.06–0.10
8M, 8MA	Type 316	S31600	≤0.08	≤2.00	≤0.045	≤0.030	≤1.00	16.0–18.0	10.0–14.0	2.0–3.0	—
8T, 8TA	Type 321	S32100	≤0.08	≤2.00	≤0.045	≤0.030	≤1.00	17.0–19.0	9.0–12.0	—	Ti ≥5×(C+N), ≤0.70
8F, 8FA	Type 303	S30300	≤0.15	≤2.00	≤0.20	≤0.15	≤1.00	17.0–19.0	8.0–10.0	—	Selenium 0.15 min
8P, 8PA	Type 305	S30500	≤0.12	≤2.00	≤0.045	≤0.030	≤1.00	17.0–19.0	11.0–13.0	—	—
8N, 8NA	Type 304N	S30451	≤0.08	≤2.00	≤0.045	≤0.030	≤1.00	18.0–20.0	8.0–11.0	—	N 0.10–0.16
8LN, 8LNA	Type 304L	S30453	≤0.030	≤2.00	≤0.045	≤0.030	≤1.00	18.0–20.0	8.0–11.0	—	N 0.10–0.16
8MN, 8MNA	Type 316N	S31651	≤0.08	≤2.00	≤0.045	≤0.030	≤1.00	16.0–18.0	10.0–13.0	2.0–3.0	N 0.10–0.16
8MLN, 8MLNA	Type 316LN	S31653	≤0.030	≤2.00	≤0.045	≤0.030	≤1.00	16.0–18.0	10.0–13.0	2.0–3.0	N 0.10–0.16
8R, 8RA	XM-19	S20910	≤0.06	4.0–6.0	≤0.045	≤0.030	≤1.00	20.5–23.5	11.5–13.5	1.5–3.0	N 0.20–0.40, Nb+Ta 0.10–0.30
8S, 8SA	S21800	S21800	≤0.10	7.0–9.0	≤0.060	≤0.030	3.5–4.5	16.0–18.0	8.0–9.0	—	N 0.08–0.18
8MLCuN / 8MLCuNA	254 SMO	S31254	≤0.020	≤1.00	≤0.030	≤0.010	≤0.80	19.5–20.5	17.5–18.5	6.0–6.5	N 0.18–0.22, Cu 0.50–1.00
8MLCuN	—	S31730	≤0.030	≤2.00	≤0.040	≤0.010	≤1.00	17.0–19.0	15.0–16.5	3.0–4.0	N 0.045, Cu 4.0–5.0
9C, 9CA	N08367	N08367	≤0.030	≤2.00	≤0.040	≤0.030	≤1.00	20.0–22.0	23.5–25.5	6.0–7.0	N 0.18–0.25, Cu 0.75

Related Rescource

https://www.wermac.org/bolts/a193-b7_a320lL7_studs.html

Related Resources

Electro Zinc Plated vs Hot-Dip Galvanized Bolts | Differences & Applications

Learn the key differences between electro zinc plated and hot-dip galvanized bolts, including coating thickness, corrosion resistance, standards, and applications.

ASTM A193 B8 vs B8M: Class 1 and Class 2 Differences Explained

ASTM A193 stud bolts are widely used in high-temperature and high-pressure applications such as flanges, pressure vessels, and piping systems.

ASTM A194 Explained: Nut Grades, Chemical Composition, and Mechanical Requirements

ASTM A194 is a material specification specifically for nuts, and it is most commonly used together with ASTM A193 (bolts