GB/T 31315 Q195 cold rolled precision welded steel tube is a cold-sized mechanical tube designed for applications requiring tighter dimensional control, cleaner surfaces, and superior formability compared to ordinary ERW structural pipe. Governed by GB/T 31315-2014 standard, this product covers cold drawn or cold rolled precision welded steel tubes for machinery, vehicle, furniture, and general engineering applications. Q195 is one of the specified steel designations with chemistry referenced to GB/T 700.

• Low-carbon Q195 chemistry for forming and welding

  Q195 is a mild carbon structural steel with C ≤ 0.12%, Si ≤ 0.30%, Mn ≤ 0.50%, providing high plasticity, excellent weldability, and reliable cold-forming behavior for sleeves, brackets, bushings, furniture frames, and light mechanical members.

• Precision geometry for assembly-fit parts

  GB/T 31315 is a precision tube standard that controls tube geometry, curvature, surface condition, and dimensional consistency for applications where normal ERW pipe is too coarse for machining, telescoping, pressing, or sliding fits.

• Controlled surface quality

  The standard requires smooth inner and outer surfaces, with local pits, scratches, and minor marks limited to a depth of 0.08 mm max, while remaining wall thickness must still stay above the minimum allowed tolerance. This is crucial for parts that will be bent, plated, painted, or directly assembled.

• Mechanical baseline suitable for light-duty structures

  Q195 typically provides yield strength ≥ 195 MPa, tensile strength 315-430 MPa, and elongation ≥ 33% for small-section reference products, making it suitable where formability is more important than high load-bearing capacity.

• Distinction from Ordinary ERW Pipe

  The key difference is the execution standard. GB/T 31315 is specifically written for cold drawn or cold rolled precision welded steel tubes for mechanical and automotive use, with requirements on dimensional accuracy, curvature, surface finish, and inspection.

• Weld-Zone Reliability Control

  GB/T 31315 references GB/T 7735-2004 eddy current testing and includes flattening and drift-expanding tests in its inspection framework. Manufacturers perform comprehensive checks including chemistry, tensile tests, flattening, flaring, NDT, surface inspection, and dimensional verification.

• Optimized for Downstream Processing

  Professional buyers prioritize stable chemistry, straightness, and surface quality. GB/T 31315 addresses all three through referenced chemistry standards, curvature limits of 1.5 mm/m and 0.1% full length for OD over 16 mm, and local surface defect depth limit of 0.08 mm, reducing rework during cutting, fixture assembly, bending, and coating.

Automotive seat guide sleeve -- Q195 precision welded tube is suitable for light-load seat guide sleeves and similar formed mechanical parts where straightness, weldability, and consistent outside diameter are more important than high structural strength. This aligns with the standard's intended fields of machinery, vehicle, furniture, and general engineering manufacture.