Can he? For example, let's say he was surrounded by a gang of thugs wearing titanium armor. Can he penetrate their armor?

Yes easily

If he had to probably, I haven't any scans to prove this though, never really seen Spidey try to pierce metal with his fists. Although he surely moves faster than sound and is a 20-40 tonner, should probably easily be able to generate that much force.

@avatar_of_green: wait wait wait, faster than sound? I mean yeah I know he can blitz a lot of characters but speed of sound , really?

Think about it, in combat he moves fast enough so that bullets, which move faster than sound seem to be moving in slow motion to him, it's been said he could casually catch or redirect bullets in flight if he wanted to but because he isn't invulnerable and the bullets still possess their real impact potential just slowed compared to him, he chooses not to, the one time he did he hurt his hand.

As for punching through Titanium, depends on how thick an inch or so... easily, thicker with some difficulty but titanium isn't that strong compared to the fictional metals such as carbonadium which BTW he has ripped through with some effort. He's strong enough to literally rip the armor off Tony Stark's back if his force field isn't up.

@chuckwolf: i guess that does make sense but that seems more like reaction speed , or if that is raw speed its pretty inconsistent with the comics because if he could move THAT fast he'd be crushing just about anybody (not that he already doesn't it would just be much easier)

He's got the physical advantage on almost anyone on Earth, Supes has that kind of speed in comics but gets hit by street-levelers and the sort very often. It's for the sake of the story that Spidey gets tagged.

Like others said depends on thickness of titanium armor,he already broke carbonadium so why not.

If it's Iron Man he's punching than no.

@avatar_of_green: I'm convinced especially if Hulk can run at 300+ mph then why not Spiderman

no scans?

Easily. He probably wouldn't even notice it.

I don't know if he could smash through it, prob make dints thoughs

Probably