NM450 equivalent equivalent ASME material
AISI 4145H is a hardenable Chromium-Molybdenum low alloy steel that is used to make various components and structures. It is notably used in oil and gas applications where secure connections are required. AISI 4145H is a heat treatable grade and is often used in the production of alloy steel drilling and production tubulars, valve components, and shafting. In order to meet the increasingly stringent standards of high-temperature, high-pressure applications, AISI 4145H has been used in lieu of other more expensive options such as AISI/SAE NM 450.
AISI/SAE NM 450, marketed under the ‘NM’ brand, is a 'wear plate' for highly wear resistant and impact resistant applications. Compared to AISI 4145H, NM 450 boasts a far superior wear resistance, allowing it to perform exceptionally well in high wear environments. NM 450 is an applicable equivalent material to AISI 4145H per ASTM A 536. However, due to its higher cost, its use has predominantly been in place of AISI 4145H despite its less impressive performance in stress and fatigue loading.
AISI/SAE 4145H is covered by ASTM A29 standard specification for General Requirements for Carbon and Alloy Steel. The chemical composition requirements for Grade 4145H shall be as defined for a Type 3 Class 3 product per ASTM A29. To meet the requirements of an AISI/SAE equivalent, the primary alloying elements in AISI/SAE 4145H are chromium and molybdenum, while AISI/SAE NM 450 is composed primarily of martensite, the primary alloy used in NM series 450.
The hardness of AISI/SAE 4145H is in the range of 269 Brinell hardness, while AISI/SAE NM 450 has a higher range of 400 Brinell hardness. The strength of AISI/SAE 4145H is rated at 170 ksi (min.), while AISI/SAE NM 450 has a higher strength rating of over 850 Mpa.
Both AISI 4145H and NM 450 are grades that showcase superior physical and mechanical characteristics, especially in harsh environments. AISI/SAE 4145H is generally more cost-effective, with the benefits outweighing any drawbacks for the majority of applications. NM 450 will typically provide a higher degree of wear resistance and strength, however, making it a more suitable alternative for more demanding wear, shock and fatigue-resistant applications.
In most instances, designers select AISI/SAE 4145H for its strength-to-weight ratio, its relatively low cost, and because it performs well in many environments, most notably those with high temperatures, pressures, and shock or impact forces. NM 450 provides an engineer with the capability to design components that withstand greater wear and increased stress and shock loading while not sacrificing weight or budget.
