ForMatter/Materials/metal/Steel 4130 (Chromoly)
mat_steel_4130

Steel 4130 (Chromoly)

low-alloy steel, chromium-molybdenum · chromoly, chrome-moly, AISI 4130, 4130 chromoly steel
highlast updated 2026-04-26
metallic 0.00
hue shift +0°

Steel with a small amount of chromium and molybdenum mixed in. Stronger than mild steel, light enough that bicycles and small aircraft are made from it, weldable by hand. The frame steel of dirt bikes, racecars, and bespoke bicycles.

Low-alloy steel containing ~1% Cr and ~0.2% Mo. Heat-treatable, weldable (TIG preferred), excellent fatigue resistance. Common tube form is air-cooled (normalized) or oil-quenched and tempered. Strength-to-weight superior to plain carbon steel.

mechanical

  • tensile_strength_mpa670
  • yield_strength_mpa435
  • elastic_modulus_gpa205
  • elongation_pct25
  • hardness_brinell197
source: MakeItFrom

thermal

  • melting_point_c1432
  • thermal_conductivity_w_mk42.7
source: MakeItFrom

Sustainability

  • embodied carbon kg co2e per kg2.4
  • sourceEditorial estimate from ICE / Granta CES EduPack class databases — industry mean, with cradle-to-gate boundary unless otherwise noted. Embodied carbon for any specific product depends on supplier mix, recycled content, and energy grid; verify against a primary source before using these numbers in a sustainability claim.
  • embodied carbon recycled kg co2e per kg0.55
  • recyclabilityhigh — alloy content does not impede ferrous recycling streams
  • biodegradableFalse
  • certifications—
  • localityspecialty mills; often imported by frame-builders in tube sets (Reynolds, Columbus, True Temper)
visual
darker gray than mild steel, often supplied with mill finish or oiled
tactile
smooth on drawn-over-mandrel tubing, satisfying density in the hand
weight perception
heavy
acoustic
long ring on tube tap — a hallmark of frame-builders' bench tests

PBR starter values

Principled BSDF defaults derived from the sphere metallic finish. Reasonable seed for Blender, Substance, Keyshot, Rhino — tune per material.

# finish:      metallic
albedo        #6e6f72
metallic      1.00
roughness     0.25
ior           1.45
transmission  0.00
clearcoat     0.00
sheen         0.00
anisotropic   0.00
copy as JSON 
{
  "albedo": "#6e6f72",
  "metallic": 1.0,
  "roughness": 0.25,
  "ior": 1.45,
  "transmission": 0.0,
  "clearcoat": 0.0,
  "sheen": 0.0,
  "anisotropic": 0.0
}
Blender 4.x Python 
# Blender 4.x — Principled BSDF
# Steel 4130 (Chromoly) · finish: metallic
import bpy
mat = bpy.data.materials.new(name="mat_steel_4130")
mat.use_nodes = True
bsdf = mat.node_tree.nodes["Principled BSDF"]
bsdf.inputs["Base Color"].default_value         = (0.1559, 0.159, 0.1683, 1.0)
bsdf.inputs["Metallic"].default_value           = 1.000
bsdf.inputs["Roughness"].default_value          = 0.250
bsdf.inputs["IOR"].default_value                = 1.450
bsdf.inputs["Transmission Weight"].default_value = 0.000
bsdf.inputs["Coat Weight"].default_value        = 0.000
bsdf.inputs["Sheen Weight"].default_value       = 0.000
bsdf.inputs["Anisotropic"].default_value        = 0.000
KeyShot Python (lux) 
# KeyShot 11+ — lux Python API, Generic material
# Steel 4130 (Chromoly) · finish: metallic
# Run from Window → Scripting Console
import lux
mat = lux.createMaterial(name="mat_steel_4130", materialType="Generic")
mat.setProperty("diffuse",      (110, 111, 114))   # 8-bit sRGB
mat.setProperty("metallic",     1.000)
mat.setProperty("roughness",    0.250)
mat.setProperty("indexOfRefraction", 1.450)
mat.setProperty("transparency", 0.000)
mat.setProperty("coatingWeight", 0.000)
Substance pbrMetalRough 
{
  "_format": "Substance Designer / Painter \u2014 pbrMetalRough constants",
  "_about": "Steel 4130 (Chromoly) \u00b7 finish: metallic",
  "baseColor": {
    "r": 0.1559,
    "g": 0.159,
    "b": 0.1683
  },
  "metallic": 1.0,
  "roughness": 0.25,
  "ior": 1.45,
  "opacity": 1.0,
  "anisotropyLevel": 0.0,
  "_notes": "Channels listed are the standard Substance pbrMetalRough output. Drop into a Uniform Color node per channel, or as the constant input on a layered stack."
}
glTF 2.0 Metallic-Roughness 
{
  "asset": {
    "version": "2.0",
    "generator": "ForMatter"
  },
  "materials": [
    {
      "name": "mat_steel_4130",
      "pbrMetallicRoughness": {
        "baseColorFactor": [
          0.1559,
          0.159,
          0.1683,
          1.0
        ],
        "metallicFactor": 1.0,
        "roughnessFactor": 0.25
      },
      "extensions": {
        "KHR_materials_ior": {
          "ior": 1.45
        }
      }
    }
  ]
}
USD Preview Surface 
# USD Preview Surface — UsdShade.MaterialLook prim attributes
# Steel 4130 (Chromoly) · finish: metallic
def Material "mat_steel_4130" {
    token outputs:surface.connect = </mat_steel_4130/PreviewSurface.outputs:surface>

    def Shader "PreviewSurface" {
        uniform token info:id = "UsdPreviewSurface"
        color3f inputs:diffuseColor = (0.1559, 0.159, 0.1683)
        float   inputs:metallic     = 1.000
        float   inputs:roughness    = 0.250
        float   inputs:ior          = 1.450
        float   inputs:opacity      = 1.000
        float   inputs:clearcoat    = 0.000
        token   outputs:surface
    }
}
↓ download glTF material
ProcessTIG Welding · Tube Butting · Brazing · CNC Milling · Heat Treatment of Steel
Used inBicycle frame · Drone Chassis
Substitutes
Steel 1018 (Mild Steel)
Titanium Grade 9 (Ti-3Al-2.5V)
Aluminum 6061

Citations