PMTSCO Material FAQ's

Acralloy is AISI/SAE 4140 / 4142 cold drawn alloy steel round. It is quenched and tempered, ground and polished.

Acralloy has satisfied the high strength precision shafting requirements of the PNW for decades. 

The hardness of Acralloy is generally 28-32 Rockwell C. Acralloy is commonly used as pin stock, and its good toughness and high strength, make it a smart choice for many heavy duty shafting applications. It's available in both standard and metric diameters.

Acralloy is a registered trademark of Pacific Machinery and Tool Steel Co

Stressproof is AISI/SAE 1144 high strength, cold drawn, free machining medium carbon steel. 

Stressproof exceeds ASTM A311, Class B.

Stressproof is made by a patented process consisting of drawing the bar through a special die under heavy draft, then stress relieving it. It has good stability and exceptional machinability. 

PMTSCO carries Stressproof in both Ground & Polished and Cold Finish.

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Stressproof is a registered trademark of Niagara LaSalle Steel

17-4 PH Stainless steel is AISI Type 630 (UNS S17400)

17-4 PH is a precipitation hardening grade, offering high strength with corrosion resistance similar to type 304 in most environments. PMTSCO carries 17-4 PH in Centerless Ground and Polished, Condition H1075. 

Why do we carry 17-4 in H1075 vs other options? Condition H1075 has been aged (precipitation hardened) at 1075 degrees F for strengthening without sacrificing the machinability of the solution annealed condition. 

303 Stainless is AISI 303 (UNS 30300) free machining stainless steel. PMTSCO offers 303 stainless in cold drawn finish.

303 is the free machining version of austenitic (non-magnetic) stainless steel. It is an 18-8 type stainless and is resistant to atmospheric corrosion, foodstuffs, most organic chemicals, and a wide variety of inorganic chemicals. 

Alloy steel has enhanced properties when compared to carbon steel.

Alloy steel contains specified quantities of alloying elements (other than carbon, and commonly accepted amounts of manganese, copper, silicon, sulfur, and phosphorus) added to effect changes in mechanical or physical properties. It is carried in many shapes and sizes. 

Some examples of alloy steels carried by PMTSCO are: 4140, 4130, 4330, 86L20, 41L40, and more

"L" in 86L20, 12L14, and 41L20 signifies the addition of Lead to the material for increased machinability. 

Interesting Fact: Lead does not alloy with steel. Instead, it is added in pellet form during teeming of the ingot, and is retained in its elemental state as a fine dispersion within the steel's structure. 

Also known as "ArrowTen". Arrow-Ten is AISI/SAE 1045 cold drawn steel that is ground and polished to insure tight diameter tolerances and 16 rms maximum surface finish.

Arrow-Ten is successfully used in many higher rpm, medium load applications such as shafts, spindles, and arbors.

Arrow-Ten is a registered trademark of Pacific Machinery and Tool Steel Company

ETD 150 is AISI/SAE 4100 Series medium carbon steel. It is a high strength alloy steel with improved machinability.

ETD stands for Elevated Temperature Drawn. 

ETD 150 is a registered trademark of Niagara LaSalle Steel 

​IHCP stands for Induction Hardened Chrome Plated and is AISI 1045/1050 steel. IHCP is notable for meeting a minimum of 100 ksi  yield strength.

Induction hardening gives IHCP a hard case on the surface for support to the chrome plating; minimizing surface damage to the chrome from abrasion and/or impact.

IHCP is a registered trademark of Niagara LaSalle

RTOS stands for Rough Turned Oversized. Many of the large diameter solid rounds that PMTSCO carries are hot rolled RTOS allowing for extra material for our customers to machine back to their own custom diameter and finish.

"FM" stands for Free Machining when in regard to our 4150 steel. Sulfur is added to increase machinability as an effective chip-breaker. Sulfur also serves to decrease transverse ductility and impact strength. Sulfur impairs weldability. 

S-CPO is "Standard Chrome Plated Only" AISI 1045 round. Standard Chrome Plating is 0.0005" min thickness.

S-CPO is a registered trademark of Pacific Machinery and Tool Steel