42CrMo thick-walled seamless steel pipe is a high-strength steel with excellent strength, toughness, and quenchability.

42CrMo Thick-Walled Seamless Steel Pipe Material Introduction

The applications of 42CrMo seamless steel pipes: The special steel grade for bridges is "42CrMo," for automotive frames it is "42CRmo," and for pressure vessels it is "42Crmo."

This type of steel improves its mechanical properties by adjusting the carbon (C) content, thus, the properties vary according to the carbon content level.

This type of steel can be further divided into: low-carbon steel -- with a carbon content generally less than 0.25%, such as 10, 20 steel, etc.

Medium carbon steel -- Carbon content typically ranges between 0.25% to 0.60%, such as 35, 45 steel, etc.

High carbon steel – carbon content generally greater than 0.60%.

This type of steel is generally not used for making steel pipes.

Material Characteristics of 42CrMo Thick-Walled Seamless Steel Pipe

No significant temper brittleness, minimal deformation during quenching, high fatigue limit and resistance to multiple impacts after tempering treatment, good low-temperature toughness, and high creep and tensile strength at elevated temperatures. The steel typically employs surface hardening after tempering as its heat treatment process.

42CrMo Heavy Wall Seamless Steel Pipe Chemical Composition

In compliance with standard GB/T3077-2018.

Chemical composition (quality fraction) of the steel:

　　Ni≤0.030%、

　　P≤0.030%、

　　S≤0.030%

42CrMo thick-walled seamless steel tube physical properties

(1) Critical Point Temperatures (approximate values): Ac1=730°C, Ac3=800°C, Ms=310°C.

(2) Coefficient of Linear Expansion: 20~100°C / 20~200°C / 20~300°C / 20~400°C / 20~500°C / 20~600°C, Coefficient of Linear Expansion: 11.1×10^-5 / 12.1×10^-5 / 12.9×10^-5 / 13.5×10^-5 / 13.9×10^-5 / 14.1×10^-5

(3) Modulus of Elasticity: 20°C/300°C/400°C/500°C/600°C, 210,000 MPa/185,000 MPa/175,000 MPa/165,000 MPa/155,000 MPa

42CrMo Thick-Walled Seamless Steel Pipe Heat Treatment Specifications

Heating temperature: 1150 ~ 1200°C, starting temperature: 1130 ~ 1180°C, termination temperature: >850°C, slow cooling when φ>50mm.

Active fire specification

The material is heated to 850~900°C and then air-cooled after being removed from the furnace.

High-Temperature Tempering Specification

Hardening temperature: 680~700°C, air-cooled after removal from the furnace.

Quenching and tempering specifications

Preheat temperature: 680 ~ 700°C, quenching temperature: 840 ~ 880°C, oil-cooled, tempering temperature: 580°C, water-cooled or oil-cooled, hardness ≤ 217HBW.

Yawei quenching and tempering treatment specification

Quenching temperature 900°C, tempering temperature 560°C, hardness (37±1) HRC

Induction hardening, tempering specifications

Quenching temperature: 900°C, tempering temperature: 150~180°C, hardness: 54~60HRC.