Which stainless steel is harder, 630 or 304 or 3 16?

630 belongs to precipitation hardening steel and can be prepared. 304 and 3 16 are austenitic stainless steels, so 630 is harder than 304 and 3 16.

AISI 630 (17-4PH) Project 70 Stainless Steel Custom 630 (17Cr-4Ni) Stainless Steel

Chemical composition:

Carbon -0.07% and highest chromium-15.00/ 17.50%

Manganese-1.00% Maximum nickel -3.00/5.00%

Phosphorus-0.040%-3.00/5.00% of the maximum copper content

Sulfur -0.030% maximum holmium &; Tantalum -0. 15/0.45%

Silicon -65438+ max. 0.00%

Description:

Stainless steel project 70 stainless steel custom-made 630 (17Cr-4Ni) improves the turning performance on the basis of traditional 630 (17Cr-4Ni). This alloy is a martensite precipitation/age hardening alloy with high strength and hardness and excellent corrosion resistance. It has good processability and can be age hardened by one-time low temperature treatment.

According to customer feedback, the turning performance of custom-made stainless steel 630 (17Cr-4Ni) of Project 70 is obviously improved and improved compared with that of ordinary custom-made 630 (17Cr-4Ni). This includes an increase in turning speed by 15% or even higher, and better final surface treatment, while prolonging tool life.

Application:

Project 70 stainless steel custom 630 (17Cr-4Ni) can be used for many different purposes, including valve parts, chemical process equipment, aircraft parts, fasteners, pump shafts, nuclear reaction parts, gears, paper machine equipment, missile parts and jet engine parts in the petroleum field.

Corrosion resistance:

The corrosion resistance of Project 70 stainless steel Custom 630 (17Cr-4Ni) is better than any other 400 series hardened stainless steel, and its corrosion resistance is almost close to that of 304 and 302 stainless steels for most corrosive substances.

By hardening at 1025℉(552℃) or higher, good stress corrosion cracking resistance can be obtained. Due to the combination of good corrosion resistance and high hardness, 17-4 stainless steel also has good pitting resistance.

According to NACE MR-0 1-75 "metal material for resisting sulfide stress cracking in oilfield equipment", the alloy can also accept the maximum hardness C33 for resisting sulfide stress cracking. Please refer to this document for detailed information under the corresponding conditions.

In order to achieve the best corrosion resistance, the surface must be free of rust and impurities, and the finished product should be passivated.

Note: Corrosion rate refers to the interval of 48 hours.

(1) During the next few or all 48-hour test phases, no rate values were displayed.

(2) By the third 48-hour test interval, the ratio increased to 200 mpy.

High temperature application:

Project 70 stainless steel custom 630 (17Cr-4Ni) shows excellent oxidation resistance at 1 100℉(539℃).

Long-term exposure to 600-900℉(288-482℃) will reduce the toughness of precipitation hardening of stainless steel. In some cases, the decrease of toughness can be minimized by using higher aging temperature.

Heat treatment:

The hardening condition of Project 70 stainless steel customized 630 (17Cr-4Ni) is that the material in condition A will reach 900 ℉ (482℃) ~1150 ℉ (621℃) for one to four hours after solution treatment by heating. Different heat treatment methods are as follows:

1) condition a (solution treatment or annealing)

Heating at1900 ℉ (1038℃) and 25 ℉ (14℃) for half an hour, and cooling to below 90℉(32℃), the material completely transforms into martensite. If the cross section is less than 3 "(76.2 mm), it can be quenched in appropriate liquid, and if the cross section is more than 3" (76.2 mm), it should be air cooled quickly. Because stress corrosion cracking is sensitive, materials that have not been age hardened cannot be used in this case.

2) Condition H 900 (precipitation or age hardening)

Heat the solution-treated material to 900℉(482℃) and keep it for 65438 0 hours, then air-cool.

3) Conditions H925, H 1025, H 1075, H 1 100, H150.

Heat the solid solution treated material to 15 ℉ (8℃) after the H character, keep it for 4 hours, and then air-cool.

4) condition h1150m

Heating the solid solution treated material to1400 ℉ (760℃)15 ℉ (8℃), keeping it for 2 hours, and then air cooling; Then heating to1150 ℉ (621℃)15 ℉ (8℃), holding for 4 hours, and then air cooling.

5) dimensional shrinkage during hardening

The precipitation hardening of Project 70 stainless steel Custom 630 (17Cr-4Ni) will be accompanied by slight dimensional changes.

When the material after solution treatment (that is, state A) is hardened to state H 900, the total shrinkage is about 0.0004 ~ 0.00006 inch/inch. (meter/meter). When the A-state material is hardened to H 1 150, the shrinkage is about 0.0009 ~ 0.000 12 inch. /yes. (meter/meter).

6) cleaning

After forging and annealing, the rust removal procedure can be pickling or sandblasting. Acid treatment is to soak in 180℉(82℃) 50% hydrochloric acid for 2 minutes, then soak in 15% nitric acid mixture for 4 minutes, and then add 3% hydrofluoric acid to room temperature. At room temperature, rinse with water in a nitric acid solution containing 20% by volume to remove stains. Repeat the above cleaning steps if necessary, but the time should be halved (that is, changed to 1 and 2 minutes respectively).

The tempering color produced by aging can be polished, steam sprayed or acid soaked with the mixed solution of 15% nitric acid and 3% hydrofluoric acid for 4~6 minutes, and then washed with clean water. If necessary, repeat the above cleaning steps, but shorten the time to 2~3 minutes. At room temperature, use a solution containing 20% nitric acid to remove stains.

After pickling, bake at 300/350 ℉ (149/177℃) for 1~3 hours to remove hydrogen.

Working performance:

1) hot working

Project 70 stainless steel customized 630 (17Cr-4Ni) can be directly used for forging, hot stamping and upsetting. If the material is required to have an appropriate hardening reaction, the material used for hot working must be solution-treated before hardening.

2) Forging

Before forging, heat it to 2 1 50/2200 ℉ (1177/1204℃) and keep it at this temperature for1hour. Forging shall not be carried out at a temperature lower than1850 ℉ (1010℃). In order to obtain the best particle size and mechanical properties, forgings should be cooled to below 90℉(32℃) in air before further processing. Forgings must be solution treated before hardening.

3) Cold working

Project 70 stainless steel custom-made 630 (17Cr-4Ni) can achieve high initial yield strength in a certain range through cold working.

4) Machining

Project 70 Stainless Steel Custom 630 (17Cr-4Ni) is in the state of solution treatment or various age hardening; Can be directly processed. In the solid solution state, processing is similar to 302 and 304 stainless steels. With the increase of quenching temperature, its cutting performance will be improved. The condition of H 1 150M can provide the best cutting performance.

The best machinability can be obtained under the condition of H 1 150M, and the higher mechanical properties can only be improved by solution and heat treatment at the standard hardening temperature.

5) welding

Project 70 stainless steel customized 630 (17Cr-4Ni) can meet the requirements of protective melting and resistance welding. Oxyacetylene welding is not recommended because it will be interfered by carbon during welding. When metal filling is needed, AWS E/ER 630 fusible covered electrode can be considered for welding to match the base metal. When setting welding points, attention should be paid to avoid stress concentration, such as small radius corners, screws and semi-permeable welded joints. When high welding strength is not required, standard austenitic stainless steel covered electrode, such as E/ER308L, can be considered. In general, solid state welding can meet the requirements; However, if strong welding stress is required, it is recommended to weld in the age hardening state (H 1 150). Generally, preheating treatment is not needed to prevent cracks.

If the alloy is welded in solution, the alloy can be aged directly after welding to obtain the required strength level. However, the best combination of strength, toughness and corrosion resistance can only be obtained by solid solution treatment of weldments before aging. If it is welded in the age hardening state, the welded part must be treated by solid solution and then by aging.

Application specification

ASTM A564 AMS5643

ASTM A704

Supply status